These studies were funded by US Public Health Services grants P01AI057005, R01AI047734, R01AI111806 and the Functional Profiling and Computational Biology Core of the University of Washington&#8217;s Center for AIDS Research (P30 AI027757).

<ol>
	<li>Domingo, E., Holland, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+virus+mutations+and+fitness+for+survival.">RNA virus mutations and fitness for survival.</a> Annu Rev Microbiol. 51, 151-178 (1997).</li><li>Domingo, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+viral+emergence.">Mechanisms of viral emergence.</a> Veterinary research. 41 (6), 38 (2010).</li><li>Martinez-Picado, J., Martinez, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HIV-1+reverse+transcriptase+inhibitor+resistance+mutations+and+fitness:+a+view+from+the+clinic+and+ex+vivo.">HIV-1 reverse transcriptase inhibitor resistance mutations and fitness: a view from the clinic and ex vivo.</a> Virus Res. 134 (1-2), 104-123 (2008).</li><li>Troyer, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variable+fitness+impact+of+HIV-1+escape+mutations+to+cytotoxic+T+lymphocyte+(CTL)+response.">Variable fitness impact of HIV-1 escape mutations to cytotoxic T lymphocyte (CTL) response.</a> PLoS Pathog. 5 (4), e1000365 (2009).</li><li>Rolland, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amino-acid+co-variation+in+HIV-1+Gag+subtype+C:+HLA-mediated+selection+pressure+and+compensatory+dynamics.">Amino-acid co-variation in HIV-1 Gag subtype C: HLA-mediated selection pressure and compensatory dynamics.</a> PLoS One. 5 (9), e12463 (2010).</li><li>Abraha, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CCR5-+and+CXCR4-tropic+subtype+C+human+immunodeficiency+virus+type+1+isolates+have+a+lower+level+of+pathogenic+fitness+than+other+dominant+group+M+subtypes:+implications+for+the+epidemic.">CCR5- and CXCR4-tropic subtype C human immunodeficiency virus type 1 isolates have a lower level of pathogenic fitness than other dominant group M subtypes: implications for the epidemic.</a> J Virol. 83 (11), 5592-5605 (2009).</li><li>Quinones-Mateu, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+dual+infection/competition+assay+shows+a+correlation+between+ex+vivo+human+immunodeficiency+virus+type+1+fitness+and+disease+progression.">A dual infection/competition assay shows a correlation between ex vivo human immunodeficiency virus type 1 fitness and disease progression.</a> J Virol. 74 (19), 9222-9233 (2000).</li><li>Ball, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparing+the+ex+vivo+fitness+of+CCR5-tropic+human+immunodeficiency+virus+type+1+isolates+of+subtypes.">Comparing the ex vivo fitness of CCR5-tropic human immunodeficiency virus type 1 isolates of subtypes.</a> B and C. J Virol. 77 (2), 1021-1038 (2003).</li><li>Lanxon-Cookson, E. 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著者は、彼らが競合する金融利害関係がないことを宣言します。本明細書に示された意見は執筆者のものであり、公式または米国国防総省や軍の部門の見解を表すものとして解釈されるべきではありません。

組換えHIV-1分子クローンと成長競合アッセイの構築：提示プロトコルは、2つの主要な部分から構成されました。二重感染した細胞培養物中で2つのウイルスを区別するためには、競合分子クローンをRT-qPCRのプライマー - プローブアッセイにより、またはサンガー配列決定によって検出することができる配列タグを含むことが重要です。このプロトコルは、HIV-1 NL4-3 VIFの同じ領域を占有し、同じアミノ酸配列をコードするが、6同義突然変異によって異なるVifAとVIFBタグを利用します。これらの変異は影響を与えないことが示されました ウイルス複製のフィットネス20。このプロトコルで使用されるPCRベースのクローニング法は、制限部位に基づくクローニングに比べ、クローニング部位を選択する際に、より柔軟性を提供します。しかし、PCRクローニングの効率は挿入サイズが増加するにつれて減少します。インサートサイズの電流制限は〜5キロバイト34です。 PCRベースのクローニングおよび部位特異mutagenesi用S、高忠実度DNAポリメラーゼの使用は、追加の変異の可能性を低減するために重要です。生成物の十分な量を得るために必要なPCRサイクルの最小数を使用することも推奨されます。我々の経験では、我々はここで説明するPCRベースのクローニングおよび部位特異的突然変異誘発の工程の後、余分な突然変異を検出しませんでした。それにもかかわらず、PCR産物は、任意の望ましくない変異を確認するために配列決定されるべきです。理想的には、全体のHIVコード領域を再配列決定されるべきです。 少なくとも三つのサンプリング時点は指数増殖期9内で検討されるべきです。ウイルスの増殖速度は、第1の成長競争のための適切な培養期間とサンプリング時間点を決定するために、毎日のサンプリングを使用して確立されなければなりません。ウイルスの増殖速度に影響を与える要因の一つは、感染（MOI）の多重度です。それはより多くのROを得るために示されたように、このプロトコルは、単一菌感染と成長の競争の両方のために0.005の合計MOIを使用しています下のMOI 9よりバスト結果。それにもかかわらず、下側のMOIは、必要に応じてより長い指数増殖期を得るために使用されるが、結果の一貫性を犠牲にすることができます。このプロトコルは、ウイルスの適応度の差が予め概して未知であると仮定すると、50：50の初期感染率を示唆しています。ウイルス複製の動態に有意差を示唆する予備的なデータがある場合しかし、等しくない入力比の使用が適切です。これらのケースでは、70：30の感染率が少なくフィットウイルスが過剰9に配置されている大規模なフィットネス差の検出を可能にすることをお勧めします。 、ウイルスの増殖動態、及びHIV-1サブタイプBを用いた競合アッセイを最適化した成長を行うためのTCID 50を測定するためのプロトコルは、PBMCを単一のドナーからNL4-3 COTB-P24、及びPBMCをHIV-する一貫性の感受性を示しましたin vitroで 1感染。培養期間このプロトコルで提示サンプリング時点は、ヒトPBMCにおいてHIV-1 M群ウイルスを研究するために適切であると思われます。単一のソースからのPBMCを使用することは非常にウイルスの複製は、異なるドナー細胞35に変化させることができるように一貫性のある結果を得ることをお勧めします。あまり望ましくないが、置換が同じプールをすべての実験全体で使用されていることを条件として、複数のドナーからプールされたPBMCを使用することができます。別の方法としては、細胞株の使用です。ここで紹介するプロトコルは、T細胞株CEMx174 23,36で正常に使用しました。しかし、播種した細胞の数は、一貫した細胞増殖を達成するために再最適化することが重要です。それは成長の競争段階で適切なサンプリング時点を決定するために、異なる細胞株において変化する可能性があるようにウイルスの増殖速度はまた、再確立されなければなりません。 適応度を計算するためのウイルスの比を決定するために、2つの異なる方法がprotocに含まれていますOL。最初は、各サンプリング時点でのウイルスcDNAのコピー数を測定するためにRT-定量PCRを使用しています。ウイルス複製適性は、その後のcDNAコピー数に基づいて、ウイルスの比から計算しました。あるいは、ウイルスの割合はVifABタグ部位でのクロマトグラムのピーク高さの比に基づいて決定することができます。二つの方法は、比較結果（ 図4）を得ました。クロマトグラムのピーク高方法が設計された配列タグなしで他のHIV-1株に適用することができます。 RT-qPCRを、ウイルスの変異体を区別するためのプライマーまたはプローブを使用することは最初に慎重に評価されなければならないために（20を参照）。しかしながら、RT-qPCRのは、指数増殖期中に最初の時点からのものなどのウイルスRNAの少量のサンプルについて良好な感度を提供します。ウイルスcDNAの直接測定は、また、RNA抽出およびcDNA合成から生じ得る技術的問題を検出することができます。配列タグとの分子クローンを使用すると、費用対効果の高いソリューションを提供するTRT-qPCRの方法Oのようなプライマーおよびプローブの2つだけのペアが複数のウイルスを研究するために必要とされます。この戦略はまた、シーケンスで、ピークの高さのばらつきの問題を回避するシーケンシングが研究中のすべてのウイルスで同じサイトで行われているように、起因隣接塩基37にクロマトグラム。 RT-qPCRのおよびサンガー配列決定のために生成されたPCR産物は、他の方法での使用は、個々のクローン12,13のバルク配列決定、HTA 4,7,17,19、またはオリゴヌクレオチドライゲーションアッセイ（OLA）38のようなウイルスの比率を決定することができ。

ウイルス複製適性は、与えられた環境で1感染性の子孫を生成するウイルスの能力として定義され、2時間かけて集団レベルでのウイルス変異の有病率を決定する重要な要因です。 in vivoでのように、トレーニングの研究では、in vitroでの様々なそのようなHIV-1などの病原性ヒトウイルス、と現実的ではないですし、ex vivoでの複製フィットネスアッセイは、薬剤耐性および免疫回避突然変異から生じるフィットネス、上位性と進化への影響を研究するために開発されてきましたウイルス集団3-6の。異なるフィットネスアッセイの中で、成長競合アッセイは、in vivo 1,7,8 で起こるように、2つ以上のウイルス変異体は、正確に同じ環境条件下で同じ細胞集団のために競うように、フィットネス差のより感度の高い、有効な対策をもたらすと認識されています。成長競合実験を開始する前に、いくつかのvariabレ感染の異なる多重度（MOI）を用い、ウイルスの入力比、および分析のためのサンプリングのタイミングを含む、決定する必要があります。我々は、ウイルスの増殖速度のと競合実験の結果に、これらのパラメータの影響を研究している、および細胞培養9中のHIV-1のフィットネスの強固な測定のために必要な重要な要素を同定しました。 変数をアッセイに加えて、成長の競合実験においてウイルス変異体を定量するための様々な方法があります。バルク10,11またはクローンの配列決定12,13は、目的の部位（複数可）でのヌクレオチドの頻度に基づいて、競合するウイルスの割合を決定するために使用されてきました。相対的なフィットネスは、時間をかけて、この比率の変化に由来します。 DNAシークエンシングサービスが広く利用可能であるように、この方法が便利です。並列対立遺伝子特異的配列決定（PASS）メソッドは、複数の部位で配列決定および組換え体14の検出を可能に</sup&gt;が、それはまた、特別に開発試薬および検出システムを必要とします。本質的に、これらの方法は、関心領域内のヌクレオチドの差異の数が少ないウイルス株を研究するために開発されました。他の方法は、4,7,17,19ヘテロトラッキングアッセイ（HTA）、配列決定によって競合ウイルスを区別するためにタグとして4,16-18小さなレポーター遺伝子15または同義突然変異を使用するか、または転写定量的リアルタイムポリメラーゼ連鎖反応を逆転します関係なく、配列類似性の競合株を研究するために適用することができるこれらの全て（RT-qPCRの）15,16,18,20、。追加のステップは、ウイルスゲノムにタグを導入するために必要であり、RT-のqPCRアッセイはまた、特異的な試薬や機器を必要とします。我々は、バルクサンガー配列決定の利回り同等の結果9。 成長競争に続いて、ウイルス複製のフィットネスは、相対フィットネス、またはTとフィットネス比として提示されていますウイルスの変異体をめざし。ウイルスの相対的な適応は、接種物中または2つの競合するウイルス間の正味の成長率の差としての最初の割合によって正規化ウイルス変異体の最終的な割合として定義することができます。我々は、後者の方法は、唯一の指数増殖期内の縦のデータポイントを使用して、最も強力な結果9,20を生じたことを発見しました。 in vitroでのフィットネスアッセイは、生物学的クローン6-8とHIV-1の感染性分子クローンを研究するために主に使用されています。後者は、遺伝子操作に適している、多くの場合、特定の突然変異または関心3-5,21,22の特定の配列から、トレーニングの効果を研究するために使用されます。次のプロトコルは、ウイルスの増殖速度を、配列タグを含むHIV-1ベクターを使用して、新しいフルレングスの感染性HIV-1分子クローンを構築する目的の変異を導入、ウイルスストックを作製し、確立した時点からワークフローを記述します、相対的なフィットネスを成長競合アッセイを実施して計算する（ 図1）。 当社の最適化された手順を使用して、我々は3組換えHIV-1変異体を作成し、それらの複製のフィットネスを決定しました。組換え分子クローンは、第1の合成COTB（センターオブと、pNL4-3のHIV-1 のgag-P24遺伝子領域、HIV-1実験室株NL4-3の全長感染性ゲノムを含むプラスミドを置換することによって構築されましたプロトタイプ株を作成するために、ツリー、サブタイプB） のgag-P24配列 23。単一アミノ酸変化（T186M、T242N、およびI256V）は、次の3つの変異体のクローンを作成するために導入されました。各変異体は、特定の遺伝的背景の各突然変異の適応度への影響を観察するために、プロトタイプのウイルスに対して競合させました。原型ウイルスよりもわずかに有意に低いから複製fsitnessのレベルを変化させることを実証し3の変異体。 T242N突然変異は、以前適度なfitneを有することが報告されましたSSは、本研究で示した結果と同様の24-26、コスト。他の2つの変異の適応コストは以前に報告されていませんでした。

<table border="0" cellpadding="0" cellspacing="0" width="1172">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Name of Material/ Equipment</td>
			<td style="width:484px;">Company</td>
			<td style="width:137px;">Catalog Number</td>
			<td style="width:196px;">Comments/Description</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Construction of recombinant clones</td>
			<td style="width:484px;"></td>
			<td style="width:137px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Chimeric primer/Mutagenic/Sequencing primers</td>
			<td style="width:484px;">IDT</td>
			<td style="width:137px;">N/A</td>
			<td>Custom DNA oligos</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">pNL4-3VifA and pNL4-3VifB plasmid</td>
			<td style="width:484px;">N/A</td>
			<td style="width:137px;">N/A</td>
			<td>Please contact Dr. James I Mullins (jmullins@uw.edu)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">High-Fidelity DNA polymerase</td>
			<td style="width:484px;">Thermo Scientific</td>
			<td>F-549S</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">High-fidelity buffer</td>
			<td style="width:484px;">Thermo Scientific</td>
			<td>F-549S</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">dNTP</td>
			<td style="width:484px;">Bioline</td>
			<td style="width:137px;">Bio-39026</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Thermal cycler</td>
			<td style="width:484px;">Life Technologies</td>
			<td style="width:137px;">N/A</td>
			<td>Applied Biosystems&#174; GeneAmp&#174; PCR System 9700</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DNA loading dye</td>
			<td style="width:484px;">Thermo Scientific</td>
			<td style="width:137px;">R0631</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1kb Plus DNA ladder</td>
			<td style="width:484px;">Invitrogen</td>
			<td style="width:137px;">10787-018</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">QIAquick PCR Purification Kit</td>
			<td style="width:484px;">Qiagen</td>
			<td style="width:137px;">28104</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">QIAquick gel extraction kit</td>
			<td style="width:484px;">Qiagen</td>
			<td style="width:137px;">28704</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">DpnI enzyme</td>
			<td style="width:484px;">New England Biolabs</td>
			<td>R0176S</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">TOP10 chemically competent Escherichia coli</td>
			<td style="width:484px;">Invitrogen</td>
			<td>C4040-10</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Luria Broth base powder</td>
			<td style="width:484px;">Invitrogen</td>
			<td style="width:137px;">12795-084</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Carbenicillin</td>
			<td style="width:484px;">Research Products International</td>
			<td style="width:137px;">C46000-25.0</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">QIAprep Spin Miniprep kit&#160;</td>
			<td style="width:484px;">Qiagen</td>
			<td style="width:137px;">27104</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">EndoFree Plasmid Maxi Kit</td>
			<td style="width:484px;">Qiagen</td>
			<td style="width:137px;">12362</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Transfection</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">X-tremeGENE 9 DNA transfection reagent</td>
			<td style="width:484px;">Roche</td>
			<td>6365787001</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">HEK 293T-17</td>
			<td style="width:484px;">ATCC</td>
			<td style="width:137px;">CRL-11268</td>
			<td>http://www.atcc.org/</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">0.22um filter top tube</td>
			<td style="width:484px;">VWR International</td>
			<td>89220-716&#160;</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cell culture</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Dulbecco&#39;s Modified Eagle Medium (DMEM)</td>
			<td style="width:484px;">Life Technologies</td>
			<td>10566016</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Iscove&#8242;s Modified Dulbecco&#8242;s Medium (IMDM)</td>
			<td style="width:484px;">Life Technologies</td>
			<td>31980-030</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">RPMI-1640 media</td>
			<td style="width:484px;">Life Technologies</td>
			<td>61870-036</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Phytohemagglutinin (PHA)</td>
			<td style="width:484px;">Thermo Scientific</td>
			<td>R30852801</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Human Interleukin-2</td>
			<td style="width:484px;">Roche</td>
			<td>11147528001</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Fetal bovine serum</td>
			<td style="width:484px;">JR Scientific</td>
			<td style="width:137px;">43640</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Penicillin and Streptomycin</td>
			<td style="width:484px;">Corning Cellgro</td>
			<td>30-001-CI</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">6 well plate</td>
			<td style="width:484px;">VWR Scientific</td>
			<td style="width:137px;">73520-906</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">48 well plate</td>
			<td style="width:484px;">VWR Scientific</td>
			<td style="width:137px;">62407-338</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">96 well flat-bottomed plate</td>
			<td style="width:484px;">ISC Bioexpress</td>
			<td style="width:137px;">T-3015-4</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">96 well round-bottomed plate</td>
			<td style="width:484px;">BD Falcon</td>
			<td style="width:137px;">353077</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">1.5 ml Microcentrifuge Tube</td>
			<td style="width:484px;">Mt. Baker Bio</td>
			<td style="width:137px;">MBD-1500</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">1.5 mL tubes w/ O-ring</td>
			<td style="width:484px;">VWR Scientific</td>
			<td style="width:137px;">89004-290</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:355px;">50 mL conical tube</td>
			<td style="width:484px;">ISC Bioexpress</td>
			<td>C-3317-6</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">ELISA</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Triton-X 100</td>
			<td style="width:484px;">Sigma-Aldrich</td>
			<td>X100</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Phosphate buffer saline (PBS)</td>
			<td style="width:484px;">Invitrogen</td>
			<td style="width:137px;">14190-250</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Fetal bovine serum (FBS)</td>
			<td style="width:484px;">Sigma-Aldrich</td>
			<td>F0392</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">glycerol</td>
			<td style="width:484px;">Sigma-Aldrich</td>
			<td style="width:137px;">G5516</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Tween 20</td>
			<td style="width:484px;">Sigma-Aldrich</td>
			<td>P1379</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Bovine Serum Albumin (BSA)</td>
			<td style="width:484px;">Sigma-Aldrich</td>
			<td>A2153</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Rabbit anti-HIV-1 SF2 p24 antiserum</td>
			<td style="width:484px;">NIH AIDS Reagent Program</td>
			<td style="width:137px;">4250</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Goat anti-rabbit HRP</td>
			<td style="width:484px;">KPL</td>
			<td style="width:137px;">474-1516</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">TMB Microwell Peroxidase Substrate</td>
			<td style="width:484px;">KPL</td>
			<td style="width:137px;">52-00-01</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">H2SO4</td>
			<td>Fisher Scientific</td>
			<td>A300-500</td>
			<td>Causes severe burns by all exposure routes. Use personal protective equipment. Use only under a chemical fume hood. Wash off immediately with plenty of water for at least 15 minutes.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">HIV p24 standard</td>
			<td style="width:484px;">AIDS and Cancer Virus program (NCI-Frederick)</td>
			<td style="width:137px;">N/A</td>
			<td>For order details please contact Julian Bess, Jr. (bessjw@mail.nih.gov); http://ncifrederick.cancer.gov/Programs/Science/Acvp/bio/Bess.aspx</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Microplate reader</td>
			<td style="width:484px;">Molecular Devices</td>
			<td style="width:137px;">N/A</td>
			<td>VMax Kinetic ELISA Microplate Reader</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">RNA isolation cDNA synthesis</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">QIAxtractor</td>
			<td style="width:484px;">Qiagen</td>
			<td style="width:137px;">N/A</td>
			<td>http://www.qiagen.com/products/catalog/automated-solutions/sample-prep/qiaxtractor</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">QIAamp Viral RNA Mini Kit</td>
			<td style="width:484px;">Qiagen</td>
			<td style="width:137px;">52906</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">dNTP</td>
			<td style="width:484px;">Bioline</td>
			<td style="width:137px;">Bio-39026</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">SuperscriptIII</td>
			<td style="width:484px;">Invitrogen</td>
			<td>18080-085</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">First-strand buffer&#160;</td>
			<td style="width:484px;">Invitrogen</td>
			<td>18080-085</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Dithiothreitol (DTT)</td>
			<td style="width:484px;">Invitrogen</td>
			<td>18080-085</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Rnase inhibitor</td>
			<td style="width:484px;">Roche</td>
			<td>3335402001</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">RnaseH</td>
			<td style="width:484px;">Invitrogen</td>
			<td>18021-071</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">qPCR</td>
			<td style="width:484px;"></td>
			<td style="width:137px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Real-time qPCR machine</td>
			<td style="width:484px;">Life Technologies</td>
			<td style="width:137px;">N/A</td>
			<td>Applied Biosystems 7300 Real-Time PCR&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">TaqMan&#174; Gene Expression Master Mix</td>
			<td style="width:484px;">Life Technologies</td>
			<td>4369016</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Forward, reverse primer</td>
			<td style="width:484px;">IDT</td>
			<td style="width:137px;">N/A</td>
			<td>Custom order</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Probe</td>
			<td style="width:484px;">Life Technologies</td>
			<td style="width:137px;">N/A</td>
			<td>Custom order</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">optical 96 well reaction plate</td>
			<td style="width:484px;">Life Technologies</td>
			<td style="width:137px;">I19N3Q216</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PCR+sequencing</td>
			<td style="width:484px;"></td>
			<td style="width:137px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Taq DNA polymerase (Biolase)</td>
			<td style="width:484px;">Bioline</td>
			<td style="width:137px;">Bio-21043</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">NH4 buffer&#160;</td>
			<td style="width:484px;">Bioline</td>
			<td style="width:137px;">Bio-21043</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">MgCl2</td>
			<td style="width:484px;">Bioline</td>
			<td style="width:137px;">Bio-21043</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Sequencing primer</td>
			<td style="width:484px;">IDT</td>
			<td style="width:137px;">N/A</td>
			<td>Custom order</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">QIAxcel</td>
			<td style="width:484px;">Qiagen</td>
			<td style="width:137px;"></td>
			<td>http://www.qiagen.com/products/catalog/automated-solutions/detection-and-analysis/qiaxcel-advanced-system</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DNA sequencing service provider</td>
			<td>http://www.htseq.org/</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">GRC web tool</td>
			<td>http://indra.mullins.microbiol.washington.edu/grc/</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">ChromatQuan web tool</td>
			<td>http://indra.mullins.microbiol.washington.edu/cgi-bin/chromatquant.cgi</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

pairwise growth competition assay for determining the replication fitness of human immunodeficiency viruses

In vitro fitness assays are essential tools for determining viral replication fitness for viruses such as HIV-1. Various measurements have been used to extrapolate viral replication fitness, ranging from the number of viral particles per infectious unit, growth rate in cell culture, and relative fitness derived from multiple-cycle growth competition assays. Growth competition assays provide a particularly sensitive measurement of fitness since the viruses are competing for cellular targets under identical growth conditions. There are several experimental factors to consider when conducting growth competition assays, including the multiplicity of infection (MOI), sampling times, and viral detection and fitness calculation methods. Each factor can affect the end result and hence must be considered carefully during the experimental design. The protocol presented here includes steps from constructing a new recombinant HIV-1 clone to performing growth competition assays and analyzing the experimental results. This protocol utilizes experimental parameter values previously shown to yield consistent and robust results. Alternatives are discussed, as some parameters need to be adjusted according to the cell type and viruses being studied. The protocol contains two alternative viral detection methods to provide flexibility as the availability of instruments, reagents and expertise varies between laboratories.

HIV-1のGag-P24における単一アミノ酸変化の適応度への影響を研究するために、我々はHIV-1 COTB-P24遺伝子23,32,33を含むpNL4-3プラスミドに変異を導入するために、オリゴヌクレオチド特異的変異誘発を使用していました。ウイルスストックは、293T細胞のトランスフェクションによって生成され、48時間後に回収しました。我々は、リード-ミュンヒ法31により各ウイルスストックの50％組織培養感染量（TCID 50）を推定しました。プロトタイプと変異体ウイルスのTCID 50は 10 4から10 5 IU / mlで（ 図3A）の範囲でした。 組換えウイルスの増殖動態は、0.005のMOIで、単一のドナーからのPBMCに設立されました。 RT-qPCRを、6日間毎日ウイルスcDNAコピー数を測定しました。ウイルスRNAのコピー数の増加の減少勾配によって示されるように、すべての変異体およびプロトタイプウイルスは&lt;（、、2日目と4日目の間に指数関数的にウイルスの増殖を遅く次のように成長しました強い&gt;図3B）。 0日目（接種物に相当）と2日目の間のcDNAコピー数の減少は、細胞へのウイルスの吸収と1日目の洗浄（ステップ5.1.6）によって結合していないビリオンの除去によるものです。指数増殖期では、すべての3つの変異体は、原型ウイルス（ 図3C）よりも遅い成長速度（g）を有していました。 すべての3つの変異体は、0.005の合計MOIで成長競合アッセイで原型ウイルス競いました。二重感染した培養物中のウイルスの増殖速度は、単一菌感染の場合と同様でした。ウイルスの指数増殖期は、2日目と4の間で、ウイルス増殖は、5日目（ 図4A）の周りにプラトーに達しました。 ウイルスの増殖速度の差は経時ウイルス比率の変化に由来しました。ウイルス比はcDNAコピーの参照の数とRT-qPCRのを使用して、変異体ウイルスであり、比較ピーク高さにより計算しましたシーケンス内の2つのウイルス（ 図4B）を区別するヌクレオチド部位でクロマトグラム。ピーク高さおよびウイルスRNAのコピー数の方法を用いて決定成長速度の違いは、同様の結果（ 図4C）を得ました。すべての3つの変異体は、最も低いフィットネス（ 図4C）を有する変異I256Vとプロトタイプのウイルスよりも低い複製のフィットネスを持っていました。 <img alt="図1" src="/files/ftp_upload/52610/52610fig1.jpg" /> 図1：本論文でのプロトコルのフロー図ウイルスストックのウイルス調製プロトコルの懸念のHIV-1組換えクローンの構築および生成。フィットネスアッセイプロトコルは、ウイルスの増殖速度を確立し、相対的なウイルスの適応度を決定するためのものです。破線は、プロトコルのための代替フローを表します。例えば、突然変異は、HIV-1 NL4-3に直接導入することができ組み換えクローンを作成することなく、分子クローン。 <img alt="図2" src="/files/ftp_upload/52610/52610fig2.jpg" /> 図2：オーバーラップ伸長PCR（A）を使用して、HIV-1 NL4-3 COTBギャグ-P24組換え分子クローンの構築キメラプライマーを設計します。 5 &#39;プライマーの半分はNL4-3ベクター配列を含み、3&#39;半分は、挿入配列の末端を含みます。 （B）キメラプライマーは、挿入断片、COTBのGag-P24を増幅するために使用されます。 （C）挿入断片は、新しい組換えプラスミドを生成するために第2のPCRのためのプライマーとして使用されます。 <img alt="図3" src="/files/ftp_upload/52610/52610fig3.jpg" /> 図3：PBMCにおけるウイルス増殖特性（A）ログ10 TCID 50 </sUB&gt;ウイルスストックの。 （B）MOI = 0.005で開始monoinfectionsにおけるウイルス増殖動態。パネル（B）に由来する指数増殖期（日2-4）を含む6日間の（C）は、ウイルスの増殖速度、。表示される値は、一つの実験からの3つの複製の平均を表します。エラーバーは95％信頼区間を表します。 <img alt="図4" src="/files/ftp_upload/52610/52610fig4.jpg" /> 図4：ウイルスの増殖および相対フィットネスの決定（A）二重感染したPBMC培養におけるウイルスの増殖。 T242Nプロトタイプウイルスの（B）比は、RT-qPCRをシークエンシングまたはピーク高さ法を用いて決定しました。 （C）二重感染した培養物中の変異体およびプロトタイプウイルス間ネットウイルス増殖率の差（D）、（A）に示すようにd値は、fを計算しました（B）に示したウイルスの割合データをROM。表示される値は、一つの実験からの3つの複製の平均を表します。エラーバーは95％信頼区間を表します。

Watch this Scientific Journal Video about Pairwise Growth Competition Assay for Determining the Replication Fitness of Human Immunodeficiency Viruses at JoVE.com

Pairwise Growth Competition Assay for Determining the Replication Fitness of Human Immunodeficiency Viruses

Growth competition between nearly isogenic viruses provides a sensitive measurement for determining relative replication fitness. The protocols described here include the construction of recombinant HIV-1 clones, virus propagation and growth competition and analysis methods optimized to yield sensitive and consistent results.

ヒト免疫不全ウイルスの複製フィットネスを決定するためのペアごとの成長競合アッセイ

In vitro fitness assays are essential tools for determining viral replication fitness for viruses such as HIV-1. Various measurements have been used to ...

pairwise-growth-competition-assay-for-determining-replication-fitness

Research

JoVE Journal

Immunology and Infection

11.0K ビュー.  University of Washington. Growth competition between nearly isogenic viruses provides a sensitive measurement for determining relative replication fitness. The protocols described here include the construction of recombinant HIV-1 clones, virus propagation and growth competition and analysis methods optimized to yield sensitive and consistent results.

ビデオ: Pairwise Growth Competition Assay for Determining the Replication Fitness of Human Immunodeficiency Viruses

Determining the Reactivity and Titre of Serum using a Haemagglutination Assay

Haemagglutination is a specific form of agglutination and is used when antibodies bind to red blood cells, which act as a particulate antigen. Red blood cells are particularly useful targets as they are readily available and agglutination is observable using the naked eye. This technique is commonly used to determine the titre of an antibody (Ab), for blood grouping and viral quantification. In this video, the steps involved in preparing and performing a haemagglutination assay is demonstrated using antibodies specific to blood group A-antigens added to red blood cells (Revercells). The antiserum is serially diluted in a 96 well U-bottom microtitre tray, to which is added a suspension of Revercells. The samples are mixed and then incubated at 37&deg;C for 60 minutes. After this time, the samples can then be easily scored for  ve, +ve and intermediate (-/+) haemagglutination reactions. This approach allows for the reactivity and titre of a serum sample to be assessed using a rapid and simple technique. The video will cover the theory behind the assay, how the results are read and interpreted, how the titre is determined, how the assay can be modified and any issues associated with the use of this technique.

Haemagglutination is a form of agglutination where antibodies bind to red blood cells. Red blood cells are both readily available and the results are readily observable using the naked eye. This video demonstrates the steps involved in a haemagglutination assay, interpreting the results and determining the titre.

赤血球凝集アッセイを用いて血清の反応性と力価の決定

Haemagglutination is a specific form of agglutination and is used when antibodies bind to red blood cells, which act as a particulate antigen. Red blood ...

免疫・感染学

Cost-effective Method for Microbial Source Tracking Using Specific Human and Animal Viruses

Microbial contamination of the environment represents a significant health risk. Classical bacterial fecal indicators have shown to have significant limitations, viruses are more resistant to many inactivation processes and standard fecal indicators do not inform on the source of contamination. The development of cost-effective methods for the concentration of viruses from water and molecular assays facilitates the applicability of viruses as indicators of fecal contamination and as microbial source tracking (MST) tools. Adenoviruses and polyomaviruses are DNA viruses infecting specific vertebrate species including humans and are persistently excreted in feces and/or urine in all geographical areas studied. In previous studies, we suggested the quantification of human adenoviruses (HAdV) and JC polyomaviruses (JCPyV) by quantitative PCR (qPCR) as an index of human fecal contamination. Recently, we have developed qPCR assays for the specific quantification of porcine adenoviruses (PAdV) and bovine polyomaviruses (BPyV) as animal fecal markers of contamination with sensitivities of 1-10 genome copies per test tube. In this study, we present the procedure to be followed to identify the source of contamination in water samples using these tools. As example of representative results, analysis of viruses in ground water presenting high levels of nitrates is shown.
Detection of viruses in low or moderately polluted waters requires the concentration of the viruses from at least several liters of water into a much smaller volume, a procedure that usually includes two concentration steps in series. This somewhat cumbersome procedure and the variability observed in viral recoveries significantly hamper the simultaneous processing of a large number of water samples.
In order to eliminate the bottleneck caused by the two-step procedures we have applied a one-step protocol developed in previous studies and applicable to a diversity of water matrices. The procedure includes: acidification of ten-liter water samples, flocculation by skimmed milk, gravity sedimentation of the flocculated materials, collection of the precipitate and centrifugation, resuspension of the precipitate in 10 ml phosphate buffer. The viral concentrate is used for the extraction of viral nucleic acids and the specific adenoviruses and polyomaviruses of interest are quantified by qPCR. High number of samples may be simultaneously analyzed using this low-cost concentration method.
The procedure has been applied to the analysis of bathing waters, seawater and river water and in this study, we present results analyzing groundwater samples. This high-throughput quantitative method is reliable, straightforward, and cost-effective.

The study describes a cost-effective method for the identification of the source of fecal/urine contamination or contamination by nitrates in water using qPCR for the specific quantification of human/porcine/bovine DNA viruses, adenoviruses and polyomaviruses, proposed as MST tools.

特定のヒトと動物のウイルスを用いた微生物ソースのトラッキングのための費用対効果の高い方法

Microbial contamination of the environment represents a significant health risk. Classical bacterial fecal indicators have shown to have significant ...

Determining Optimal Cytotoxic Activity of Human Her2neu Specific CD8 T cells by Comparing the Cr51 Release Assay to the xCELLigence System

Cytotoxic CD8 T cells constitute a subgroup of T cells that are capable of inducing the death of infected or malignant host cells1. These cells express a specialized receptor, called the T cell receptor (TCR), which can recognize a specific antigenic peptide bound to HLA class I molecules2. Engagement of infected cells or tumor cells through their HLA class I molecule results in production of lytic molecules such as granzymes and perforin resulting in target cell death. While it is useful to determine frequencies of antigen-specific CD8 T cells using assays such as the ELIspot or flow cytometry, it is also helpful to ascertain the strength of CD8 T cell responses using cytotoxicity assays3. The most recognizable assay for assessing cytotoxic function is the Chromium Release Assay (CRA), which is considered a standard assay 4. The CRA has several limitations, including exposure of cells to gamma radiation, lack of reproducibility, and a requirement for large numbers of cells. Over the past decade, there has been interest in adopting new strategies to overcome these limitations. Newer approaches include those that measure caspase 
release 4, BLT esterase activity 5 and surface expression of CD107 6. The impedance-based assay, using the Roche xCelligence system, was examined in the present paper for its potential as an alternative to the CRA. Impedance or opposition to an electric current occurs when adherent tumor cells bind to electrode plates. Tumor cells detach following killing and electrical impedance is reduced which can be measured by the xCelligence system. The ability to adapt the impedance-based approach to assess cell-mediated killing rests on the observation that T cells do not adhere tightly to most surfaces and do not appear to have much impact on impedance thus diminishing any concern of direct interference of the T cells with the measurement. Results show that the impedance-based assay can detect changes in the levels of antigen-specific cytotoxic CD8 T cells with increased sensitivity relative to the standard CRA. Based on these results, impedance-based approaches may be good alternatives to CRAs or other approaches that aim to measure cytotoxic CD8 T cell functionality.

The chromium release assay, a common assay for detecting cytotoxic T cell activity, has several limitations. Using antigen-specific CD8 T cells and the human breast cancer tumor line, SKBR3, in the present article, an impedance-based approach was examined for the capability of detecting cell killing.

xCELLigenceシステムにCR51リリースアッセイを比較することによって、人間Her2neu特異的CD8 T細胞の最適な細胞傷害活性を決定する

Cytotoxic CD8 T cells constitute a subgroup of T  cells that are capable of inducing the death of infected or malignant host  cells1. These cells express ...

Determining Soil-transmitted Helminth Infection Status and Physical Fitness of School-aged Children

Soil-transmitted helminth (STH) infections are common. Indeed, more than 1 billion people are affected, mainly in the developing world where poverty prevails and hygiene behavior, water supply, and sanitation are often deficient1,2. Ascaris lumbricoides, Trichuris trichiura, and the two hookworm species, Ancylostoma duodenale and Necator americanus, are the most prevalent STHs3. The estimated global burden due to hookworm disease, ascariasis, and trichuriasis is 22.1, 10.5, and 6.4 million disability-adjusted life years (DALYs), respectively4. Furthermore, an estimated 30-100 million people are infected with Strongyloides stercoralis, the most neglected STH species of global significance which arguably also causes a considerable public health impact5,6. Multiple-species infections (i.e., different STHs harbored in a single individual) are common, and infections have been linked to lowered productivity and thus economic outlook of developing countries1,3.
For the diagnosis of common STHs, the World Health Organization (WHO) recommends the Kato-Katz technique7,8, which is a relatively straightforward method for determining the prevalence and intensity of such infections. It facilitates the detection of parasite eggs that infected subjects pass in their feces.
With regard to the diagnosis of S.stercoralis, there is currently no simple and accurate tool available. The Baermann technique is the most widely employed method for its diagnosis. The principle behind the Baermann technique is that active S.stercoralis larvae migrate out of an illuminated fresh fecal sample as the larvae are phototactic9. It requires less sophisticated laboratory materials and is less time consuming than culture and immunological methods5.
Morbidities associated with STH infections range from acute but common symptoms, such as abdominal pain, diarrhea, and pruritus, to chronic symptoms, such as anemia, under- and malnutrition, and cognitive impairment10. Since the symptoms are generally unspecific and subtle, they often go unnoticed, are considered a normal condition by affected individuals, or are treated as symptoms of other diseases that might be more common in a given setting. Hence, it is conceivable that the true burden of STH infections is underestimated by assessment tools relying on self-declared signs and symptoms as is usually the case in population-based surveys.
In the late 1980s and early 1990s, Stephenson and colleagues highlighted the possibility of STH infections lowering the physical fitness of boys aged 6-12 years11,12. This line of scientific inquiry gained new momentum recently13,14,15. The 20-meter (m) shuttle run test was developed and validated by L&eacute;ger et al.16 and is used worldwide to measure the aerobic fitness of children17. The test is easy to standardize and can be performed wherever a 20-m long and flat running course and an audio source are available, making its use attractive in resource-constrained settings13. To facilitate and standardize attempts at assessing whether STH infections have an effect on the physical fitness of school-aged children, we present methodologies that diagnose STH infections or measure physical fitness that are simple to execute and yet, provide accurate and reproducible outcomes. This will help to generate new evidence regarding the health impact of STH infections.

Chronic infection with soil-transmitted helminths (STHs) causes malabsorption, stunting, and wasting in the growing child. Hence, it is plausible that these infections also reduce the physical fitness of children. Here, we visualize two techniques for the diagnosis of STHs and the 20-meter shuttle run test for assessing children's physical fitness.

土壌伝播蠕虫の感染状況及び学齢児童の体力を決定

Soil-transmitted helminth (STH) infections are common. Indeed, more than 1 billion people are affected, mainly in the developing world where poverty ...

A Visual Assay to Monitor T6SS-mediated Bacterial Competition

Type VI secretion systems (T6SSs) are molecular nanomachines allowing Gram-negative bacteria to transport and inject proteins into a wide variety of target cells1,2. The T6SS is composed of 13 core components and displays structural similarities with the tail-tube of bacteriophages3. The phage uses a tube and a puncturing device to penetrate the cell envelope of target bacteria and inject DNA. It is proposed that the T6SS is an inverted bacteriophage device creating a specific path in the bacterial cell envelope to drive effectors and toxins to the surface. The process could be taken further and the T6SS device could perforate other cells with which the bacterium is in contact, thus injecting the effectors into these targets. The tail tube and puncturing device parts of the T6SS are made with Hcp and VgrG proteins, respectively4,5.
The versatility of the T6SS has been demonstrated through studies using various bacterial pathogens. The Vibrio cholerae T6SS can remodel the cytoskeleton of eukaryotic host cells by injecting an "evolved" VgrG carrying a C-terminal actin cross-linking domain6,7. Another striking example was recently documented using Pseudomonas aeruginosa which is able to target and kill bacteria in a T6SS-dependent manner, therefore promoting the establishment of bacteria in specific microbial niches and competitive environment8,9,10.
In the latter case, three T6SS-secreted proteins, namely Tse1, Tse2 and Tse3 have been identified as the toxins injected in the target bacteria (Figure 1). The donor cell is protected from the deleterious effect of these effectors via an anti-toxin mechanism, mediated by the Tsi1, Tsi2 and Tsi3 immunity proteins8,9,10. This antimicrobial activity can be monitored when T6SS-proficient bacteria are co-cultivated on solid surfaces in competition with other bacterial species or with T6SS-inactive bacteria of the same species8,11,12,13.
The data available emphasized a numerical approach to the bacterial competition assay, including time-consuming CFU counting that depends greatly on antibiotic makers. In the case of antibiotic resistant strains like P. aeruginosa, these methods can be inappropriate. Moreover, with the identification of about 200 different T6SS loci in more than 100 bacterial genomes14, a convenient screening tool is highly desirable. We developed an assay that is easy to use and requires standard laboratory material and reagents. The method offers a rapid and qualitative technique to monitor the T6SS-dependent bactericidal/bacteriostasis activity by using a reporter strain as a prey (in this case Escherichia coli DH5&alpha;) allowing a-complementation of the lacZ gene. Overall, this method is graphic and allows rapid identification of T6SS-related phenotypes on agar plates. This experimental protocol may be adapted to other strains or bacterial species taking into account specific conditions such as growth media, temperature or time of contact.

We describe a qualitative assay to monitor bacterial competition mediated by the Pseudomonas aeruginosa type VI secretion system (T6SS). The assay relies on the survival/killing of Escherichia coli target cells carrying a lacZ-reporter. This technique is adjustable to assess the bactericidal/bacteriostasis activity of T6SS-proficient microorganisms.

T6SS媒介細菌競争を監視するには、Visualアッセイ

Type VI secretion systems (T6SSs) are molecular  nanomachines allowing Gram-negative bacteria to transport and inject proteins  into a wide variety of ...

Establishing a Liquid-covered Culture of Polarized Human Airway Epithelial Calu-3 Cells to Study Host Cell Response to Respiratory Pathogens In vitro

The apical and basolateral surfaces of airway epithelial cells demonstrate directional responses to pathogen exposure in vivo. Thus, ideal in vitro models for examining cellular responses to respiratory pathogens polarize, forming apical and basolateral surfaces. One such model is differentiated normal human bronchial epithelial cells (NHBE). However, this system requires lung tissue samples, expertise isolating and culturing epithelial cells from tissue, and time to generate an air-liquid interface culture.
Calu-3 cells, derived from a human bronchial adenocarcinoma, are an alternative model for examining the response of proximal airway epithelial cells to respiratory insult1, pharmacological compounds2-6, and bacterial7-9 and viral pathogens, including influenza virus, rhinovirus and severe acute respiratory syndrome - associated coronavirus10-14. Recently, we demonstrated that Calu-3 cells are susceptible to respiratory syncytial virus (RSV) infection in a manner consistent with NHBE15,16 . Here, we detail the establishment of a polarized, liquid-covered culture (LCC) of Calu-3 cells, focusing on the technical details of growing and culturing Calu-3 cells, maintaining cells that have been cultured into LCC, and we present the method for performing respiratory virus infection of polarized Calu-3 cells.
To consistently obtain polarized Calu-3 LCC, Calu-3 cells must be carefully subcultured before culturing in Transwell inserts. Calu-3 monolayer cultures should remain below 90% confluence, should be subcultured fewer than 10 times from frozen stock, and should regularly be supplied with fresh medium. Once cultured in Transwells, Calu-3 LCC must be handled with care. Irregular media changes and mechanical or physical disruption of the cell layers or plates negatively impact polarization for several hours or days. Polarization is monitored by evaluating trans-epithelial electrical resistance (TEER) and is verified by evaluating the passive equilibration of sodium fluorescein between the apical and basolateral compartments17,18 . Once TEER plateaus at or above 1,000 &Omega;&times;cm2, Calu-3 LCC are ready to use to examine cellular responses to respiratory pathogens.

Establishing a Liquid-covered Culture of Polarized Human Airway Epithelial Calu-3 Cells to Study Host Cell Response to Respiratory Pathogens In vitro

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

呼吸器病原体に対する宿主細胞応答を研究するために偏ヒト気道上皮Calu-3細胞の液体に覆われた文化の確立<em&gt;インビトロ</em

The  apical and basolateral surfaces of airway epithelial cells demonstrate  directional responses to pathogen exposure in  vivo. Thus, ideal in vitro ...

A Restriction Enzyme Based Cloning Method to Assess the In vitro Replication Capacity of HIV-1 Subtype C Gag-MJ4 Chimeric Viruses

The protective effect of many HLA class I alleles on HIV-1 pathogenesis and disease progression is, in part, attributed to their ability to target conserved portions of the HIV-1 genome that escape with difficulty. Sequence changes attributed to cellular immune pressure arise across the genome during infection, and if found within conserved regions of the genome such as Gag, can affect the ability of the virus to replicate in vitro. Transmission of HLA-linked polymorphisms in Gag to HLA-mismatched recipients has been associated with reduced set point viral loads. We hypothesized this may be due to a reduced replication capacity of the virus. Here we present a novel method for assessing the in vitro replication of HIV-1 as influenced by the gag gene isolated from acute time points from subtype C infected Zambians. This method uses restriction enzyme based cloning to insert the gag gene into a common subtype C HIV-1 proviral backbone, MJ4. This makes it more appropriate to the study of subtype C sequences than previous recombination based methods that have assessed the in vitro replication of chronically derived gag-pro sequences. Nevertheless, the protocol could be readily modified for studies of viruses from other subtypes. Moreover, this protocol details a robust and reproducible method for assessing the replication capacity of the Gag-MJ4 chimeric viruses on a CEM-based T cell line. This method was utilized for the study of Gag-MJ4 chimeric viruses derived from 149 subtype C acutely infected Zambians, and has allowed for the identification of residues in Gag that affect replication. More importantly, the implementation of this technique has facilitated a deeper understanding of how viral replication defines parameters of early HIV-1 pathogenesis such as set point viral load and longitudinal CD4+ T cell decline.

A Restriction Enzyme Based Cloning Method to Assess the In vitro Replication Capacity of HIV-1 Subtype C Gag-MJ4 Chimeric Viruses

HIV-1 pathogenesis is defined by both viral characteristics and host genetic factors. Here we describe a robust method that allows for reproducible measurements to assess the impact of the gag gene sequence variation on the in vitro replication capacity of the virus.

評価するために制限酵素ベースのクローニング方法<em&gt;インビトロ</em&gt; HIV-1サブタイプC Gag特異MJ4キメラウイルスの複製能力

The protective effect of many HLA class I alleles on HIV-1 pathogenesis and disease progression is, in part, attributed to their ability to target ...

Intranasal Administration of Recombinant Influenza Vaccines in Chimeric Mouse Models to Study Mucosal Immunity

Vaccines are one of the greatest achievements of mankind, and have saved millions of lives over the last century. Paradoxically, little is known about the physiological mechanisms that mediate immune responses to vaccines perhaps due to the overall success of vaccination, which has reduced interest into the molecular and physiological mechanisms of vaccine immunity. However, several important human pathogens including influenza virus still pose a challenge for vaccination, and may benefit from immune-based strategies. 
Although influenza reverse genetics has been successfully applied to the generation of live-attenuated influenza vaccines (LAIVs), the addition of molecular tools in vaccine preparations such as tracer components to follow up the kinetics of vaccination in vivo, has not been addressed. In addition, the recent generation of mouse models that allow specific depletion of leukocytes during kinetic studies has opened a window of opportunity to understand the basic immune mechanisms underlying vaccine-elicited protection. Here, we describe how the combination of reverse genetics and chimeric mouse models may help to provide new insights into how vaccines work at physiological and molecular levels, using as example a recombinant, cold-adapted, live-attenuated influenza vaccine (LAIV). We utilized laboratory-generated LAIVs harboring cell tracers as well as competitive bone marrow chimeras (BMCs) to determine the early kinetics of vaccine immunity and the main physiological mechanisms responsible for the initiation of vaccine-specific adaptive immunity. In addition, we show how this technique may facilitate gene function studies in single animals during immune responses to vaccines. We propose that this technique can be applied to improve current prophylactic strategies against pathogens for which urgent medical countermeasures are needed, for example influenza, HIV, Plasmodium, and hemorrhagic fever viruses such as Ebola virus.

There is an overall lack of knowledge about how vaccines work. Here we propose the combined use of reverse genetics and bone marrow chimeric mice to gain insight into the early host immune responses to vaccines with a special focus on dendritic cells and T cell immunity.

キメラマウスモデルにおける組換えインフルエンザワクチンの鼻腔内投与は、粘膜免疫を研究するために、

Vaccines are one of the greatest achievements of mankind, and have saved millions of lives over the last century. Paradoxically, little is known about the ...

Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals

The neuraminidase (NA) inhibitors are the only class of antivirals approved for the treatment and prophylaxis of influenza that are effective against currently circulating strains. In addition to their use in treating seasonal influenza, the NA inhibitors have been stockpiled by a number of countries for use in the event of a pandemic. It is therefore important to monitor the susceptibility of circulating influenza viruses to this class of antivirals. There are different types of assays that can be used to assess the susceptibility of influenza viruses to the NA inhibitors, but the enzyme inhibition assays using either a fluorescent substrate or a chemiluminescent substrate are the most widely used and recommended. This protocol describes the use of a fluorescence-based assay to assess influenza virus susceptibility to NA inhibitors. The assay is based on the NA enzyme cleaving the 2&#8242;-(4-Methylumbelliferyl)-&#945;-D-N-acetylneuraminic acid (MUNANA) substrate to release the fluorescent product 4-methylumbelliferone (4-MU). Therefore, the inhibitory effect of an NA inhibitor on the influenza virus NA is determined based on the concentration of the NA inhibitor that is required to reduce 50% of the NA activity, given as an IC50 value.

We describe the use of a phenotypic fluorescence-based neuraminidase inhibition assay to assess the susceptibility of influenza A and B viruses to the neuraminidase inhibitor class of antivirals.

蛍光ベースのノイラミニダーゼ阻害アッセイ抗ウイルスのノイラミニダーゼ阻害剤クラスにインフルエンザウイルスの感受性を評価します

The neuraminidase (NA) inhibitors are the only class of antivirals approved for the treatment and prophylaxis of influenza that are effective against ...

Ex Vivo Infection of Human Lymphoid Tissue and Female Genital Mucosa with Human Immunodeficiency Virus 1 and Histoculture

Histocultures allow studying intercellular interactions within human tissues, and they can be employed to model host-pathogen interactions under controlled laboratory conditions. Ex vivo infection of human tissues with human immunodeficiency virus (HIV), among other viruses, has been successfully used to investigate early disease pathogenesis, as well as a platform to test the efficacy and toxicity of antiviral drugs. In the present protocol, we explain how to process and infect with HIV-1 tissue explants from human tonsils and cervical mucosae, and maintain them in culture on top of gelatin sponges at the liquid-air interface for about two weeks. This non-polarized culture setting maximizes access to nutrients in culture medium and oxygen, although progressive loss of tissue integrity and functional architectures remains its main limitation. This method allows monitoring HIV-1 replication and pathogenesis using several techniques, including immunoassays, qPCR, and flow cytometry. Of importance, the physiologic variability between tissue donors, as well as between explants from different areas of the same specimen, may significantly affect experimental results. To ensure result reproducibility, it is critical to use an adequate number of explants, technical replicates, and donor-matched control conditions to normalize the results of the experimental treatments when compiling data from multiple experiments (i.e., conducted using tissue from different donors) for statistical analysis.

Ex Vivo Infection of Human Lymphoid Tissue and Female Genital Mucosa with Human Immunodeficiency Virus 1 and Histoculture

Infection of human tissues with human immunodeficiency virus (HIV) ex vivo provides a valuable 3D model of virus pathogenesis. Here, we describe a protocol to process and infect tissue specimens from human tonsils and female genital mucosae with HIV-1 and maintain them in culture at the liquid-air interface.