Name: forward genetic approaches in chlamydia trachomatis
Uploaded: 2013-10-23T18:30:00
Description: Watch this Scientific Journal Video about Forward Genetic Approaches in Chlamydia trachomatis at JoVE.com

1. الطفرات الكيميائية ملاحظة: لقد وجدنا أن النموذج RB تنسخي هو أكثر استعدادا للالطفرات الكيميائية من شكل EB. في منتصف الدورة (بين 18 إلى 20 HPI)، المكاتب الإقليمية هي في أكبر عدد قبل RB-EB الانتقالية. لأن الكلاميديا ​​هو الممرض داخل ال...

<ol>
	<li>Haggerty, C. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Risk+of+sequelae+after+Chlamydia+trachomatis+genital+infection+in+women.">Risk of sequelae after Chlamydia trachomatis genital infection in women.</a> J Infect Dis. 201, S134-S155 (2010).</li><li>Dautry-Varsat, A., Subtil, A., Hackstadt, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+insights+into+the+mechanisms+of+Chlamydia+entry.">Recent insights into the mechanisms of Chlamydia entry.</a> Cell Microbiol. 7 (12), 1714-1722 (2005).</li><li>Hybiske, K., Stephens, R. S. <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+Chlamydia+trachomatis+entry+into+nonphagocytic+cells.">Mechanisms of Chlamydia trachomatis entry into nonphagocytic cells.</a> Infect Immun. 75 (8), 3925-3934 (2007).</li><li>Heuer, D., Kneip, C., Maurer, A. P., Meyer, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tackling+the+intractable+-+approaching+the+genetics+of+Chlamydiales.">Tackling the intractable - approaching the genetics of Chlamydiales.</a> Int J Med Microbiol. 297 (7-8), 569-576 (2007).</li><li>Stephens, R. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome+sequence+of+an+obligate+intracellular+pathogen+of+humans,+Chlamydia+trachomatis.">Genome sequence of an obligate intracellular pathogen of humans, Chlamydia trachomatis.</a> Science. 282 (5389), 754-759 (1998).</li><li>Thomson, N. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chlamydia+trachomatis,+genome+sequence+analysis+of+lymphogranuloma+venereum+isolates.">Chlamydia trachomatis, genome sequence analysis of lymphogranuloma venereum isolates.</a> Genome Res. 18 (1), 161-171 (2008).</li><li>Harris, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole-genome+analysis+of+diverse+Chlamydia+trachomatis+strains+identifies+phylogenetic+relationships+masked+by+current+clinical+typing.">Whole-genome analysis of diverse Chlamydia trachomatis strains identifies phylogenetic relationships masked by current clinical typing.</a> Nat Genet. 44 (4), 413-419 (2012).</li><li>Somboonna, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypervirulent+Chlamydia+trachomatis+clinical+strain+is+a+recombinant+between+lymphogranuloma+venereum+(L(2))+and+D+lineages.">Hypervirulent Chlamydia trachomatis clinical strain is a recombinant between lymphogranuloma venereum (L(2)) and D lineages.</a> MBio. 2 (3), e00045-00011 (2011).</li><li>Voigt, A., Schofl, G., Saluz, H. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Chlamydia+psittaci+genome,+a+comparative+analysis+of+intracellular+pathogens.">The Chlamydia psittaci genome, a comparative analysis of intracellular pathogens.</a> PLoS One. 7 (4), e35097 (2012).</li><li>Jeffrey, B. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome+sequencing+of+recent+clinical+Chlamydia+trachomatis+strains+identifies+loci+associated+with+tissue+tropism+and+regions+of+apparent+recombination.">Genome sequencing of recent clinical Chlamydia trachomatis strains identifies loci associated with tissue tropism and regions of apparent recombination.</a> Infect Immun. 78 (6), 2544-2553 (2010).</li><li>Gomes, J. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+Chlamydia+trachomatis+diversity+occurs+by+widespread+interstrain+recombination+involving+hotspots.">Evolution of Chlamydia trachomatis diversity occurs by widespread interstrain recombination involving hotspots.</a> Genome Res. 17 (1), 50-60 (2007).</li><li>DeMars, R., Weinfurter, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interstrain+gene+transfer+in+Chlamydia+trachomatis+in+vitro,+mechanism+and+significance.">Interstrain gene transfer in Chlamydia trachomatis in vitro, mechanism and significance.</a> J Bacteriol. 190 (5), 1605-1614 (2008).</li><li>Demars, R., Weinfurter, J., Guex, E., Lin, J., Potucek, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lateral+gene+transfer+in+vitro+in+the+intracellular+pathogen+Chlamydia+trachomatis.">Lateral gene transfer in vitro in the intracellular pathogen Chlamydia trachomatis.</a> J Bacteriol. 189 (3), 991-1003 (2007).</li><li>Nguyen, B. D., Valdivia, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Virulence+determinants+in+the+obligate+intracellular+pathogen+Chlamydia+trachomatis+revealed+by+forward+genetic+approaches.">Virulence determinants in the obligate intracellular pathogen Chlamydia trachomatis revealed by forward genetic approaches.</a> Proc Natl Acad Sci U S A. 109 (4), 1263-1268 (2012).</li><li>Tipples, G., McClarty, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+initial+characterization+of+a+series+of+Chlamydia+trachomatis+isolates+selected+for+hydroxyurea+resistance+by+a+stepwise+procedure.">Isolation and initial characterization of a series of Chlamydia trachomatis isolates selected for hydroxyurea resistance by a stepwise procedure.</a> J Bacteriol. 173 (16), 4932-4940 (1991).</li><li>Wang, L. L., Henson, E., McClarty, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+trimethoprim-+and+sulphisoxazole-resistant+Chlamydia+trachomatis.">Characterization of trimethoprim- and sulphisoxazole-resistant Chlamydia trachomatis.</a> Mol Microbiol. 14 (2), 271-281 (1994).</li><li>Scidmore, 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=Cultivation+and+Laboratory+Maintenance+of+Chlamydia+trachomatis.">Cultivation and Laboratory Maintenance of Chlamydia trachomatis.</a> Curr Protoc Microbiol. Chapter 11, Unit 11A 11 (2005).</li><li>Li, H., Ruan, J., Durbin, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+short+DNA+sequencing+reads+and+calling+variants+using+mapping+quality+scores.">Mapping short DNA sequencing reads and calling variants using mapping quality scores.</a> Genome Res. 18 (11), 1851-1858 (2008).</li><li>Li, H., Durbin, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+and+accurate+short+read+alignment+with+Burrows-Wheeler+transform.">Fast and accurate short read alignment with Burrows-Wheeler transform.</a> Bioinformatics. 25 (14), 1754-1760 (2009).</li><li>Suchland, R. J., Sandoz, K. M., Jeffrey, B. M., Stamm, W. E., Rockey, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Horizontal+transfer+of+tetracycline+resistance+among+Chlamydia+spp.+in+vitro.">Horizontal transfer of tetracycline resistance among Chlamydia spp. in vitro.</a> Antimicrob Agents Chemother. 53 (11), 4604-4611 (2009).</li><li>Sladek, F. M., Melian, A., Howard-Flanders, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Incision+by+UvrABC+excinuclease+is+a+step+in+the+path+to+mutagenesis+by+psoralen+crosslinks+in+Escherichia+coli.">Incision by UvrABC excinuclease is a step in the path to mutagenesis by psoralen crosslinks in Escherichia coli.</a> Proc Natl Acad Sci U S A. 86 (11), 3982-3986 (1989).</li><li>Wang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+transformation+system+for+Chlamydia+trachomatis,+restoration+of+glycogen+biosynthesis+by+acquisition+of+a+plasmid+shuttle+vector.">Development of a transformation system for Chlamydia trachomatis, restoration of glycogen biosynthesis by acquisition of a plasmid shuttle vector.</a> PLoS Pathog. 7 (9), e1002258 (2011).</li></ol>

هذه المنهجية يلبي المتطلبات الأساسية للتحليل الجيني كما أنها تضع الربط بين الأنماط الجينية والظواهر. الأهم من ذلك، ويتحقق هذا بدون مساعدة من الأدوات الجزيئية التقليدية للتحول الحمض النووي المؤتلف وتعطيل غرزي من الجينات في البكتيريا، والتي غالبا ما يكون معدل الحد خ...

وتلزم بين الخلايا بكتيريا الكلاميديا ​​حسابات لما يقدر بنحو 2.8 مليون التهابات المسالك التناسلية سنويا في الولايات المتحدة (مركز السيطرة على الأمراض) مع عقابيل المرتبطة بها مثل مرض التهاب الحوض، والحمل خارج الرحم، والعقم (1). الكلاميديا ​​SPP دينا فريدة من نوعها علم وظائف الأعضاء مع دورة التنموية ثنائي الطور تتكون من شكلين: الجسم الابتدائية المعدية ولكن غير المتماثل (EB) والجسم شبكي غير المعدية ولكن تنسخي (RB). تبدأ العدوى مع المرفق من EBS إلى الخلايا الظهارية تليها endoctyotosis (2). ضمن يطلق عليه فجوة غشاء محدد إدراج، EBS تفرق في شكل RB، الذي يعيد ثم بواسطة الانشطار الثنائي. في منتصف الدورة، والتحولات المكاتب الإقليمية مرة أخرى إلى EBS، التي يتم إطلاقها في الفضاء خارج الخلية لبدء جولات جديدة من حالات العدوى عند lyses الخلية المضيفة (3). C. المتدثرة هوصهر للتلاعب الروتينية مع الأدوات الوراثية الجزيئية القياسية، مثل استبدال الجينات المستهدفة، الترانسبوزونات وفاجات transducing، والتي كانت محور معظم الدراسات في مجال علم الوراثة البكتيرية، وليس من الواضح إلى أي مدى تسهم جينات الكلاميديا ​​الفرد إلى التهرب من المناعة الفطرية ، واقتناء المواد الغذائية، والتحولات التنموية، أو غيرها من العمليات الهامة لبقاء الممرض ضمن مجموعة حقيقية النواة (4). وبناء على ذلك، لا يزال هذا الممرض تتميز سيئة على الرغم من أهميتها السريرية. جينوم الكلاميديا ​​النيابة. هي صغيرة نسبيا (~ 1 ميغابايت) (5) مع أنواع متعددة ومتسلسلة biovars باستخدام تقنيات التسلسل التالي جيل. وقد وفرت تحليل الجينوم المقارن من قبل الفريق العامل المعني بالحالات رؤى فريدة حول تطور الأنواع الناجمة عن المتدثرة وتكيفها مع البشر (6-8) وإلى حد ما وقد وفرت بعض المعلومات عن وظيفة المحتملة للعوامل الفوعة (9، 10). Tكان التنوع الجيني المعروضة بواسطة العزلات السريرية لا يوفر القرار اللازم لتعيين منهجي وظيفة معظم عوامل الفوعة، ربما لأن الطفرات في هذه الجينات قد تم اختيارها بسهولة ضد. دون آثار الخلط من الانتقاء الطبيعي، المغير الناجم عن اختلاف الجينات، إلى جانب فحوصات محددة أن العيوب التدبير في الفوعة، يمكن توسيع الطيف من الطفرات التي يمكن شملها الاستطلاع. المطفرة الكيميائية، على وجه الخصوص، هي مفيدة لأنها يمكن أن تولد فارغة، مشروط، hypomorphic (وظيفة انخفاض)، وhypermorphic (كسب وظيفة) الأليلات. مع وصول تكنولوجيات الجينوم التسلسل قوية من الجيل التالي، مثل هذه الطفرات يمكن تحديدها بسهولة وتعيينها. بهذه الطريقة، يمكن جعل جمعيات قوية بين طفرات في الجينات الوراثية أو مسار والنمط الظاهري شيوعا، وتمكن من تطبيق النهج الوراثية إلى الأمام. تسلسل جينوم سلالات السريرية كشفت الاصباغ بserovars إلى صف ومواضع من إعادة التركيب المتكرر (11). وقد تجلى الأدلة التجريبية من إعادة التركيب من خلال الرئيسين إصابة اثنين من مختلف السلالات المقاومة للمضادات الحيوية واختيار مزدوج ذرية المؤتلف مقاومة، الذي أنزل على ديها مساهمات الجينية من كلتا السلالتين (12، 13). وهكذا فإن التبادل الجيني بين نوع البرية وسلالات متحولة في إعداد العدوى المشتركة يسمح الفصل بين الطفرات التي يسببها كيميائيا لتحديد الجينات المتضررة أن يؤدي إلى النمط الظاهري المرصودة. نحن هنا وصف منهجية لإجراء تحليل وراثي في الكلاميديا ​​يعتمد على الطفرات الكيميائية، الفريق العامل المعني بالحالات، ونظام لتبادل الحمض النووي داخل الخلايا المصابة (14) (الشكل 1).

<table border="0" cellspacing="0" cols="4">
	<colgroup width="291">
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	<colgroup width="144">
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	<colgroup width="84">
	</colgroup>
	<tbody>
		<tr>
			<td>Dulbecco&#8217;s Modified Eagle Medium (DMEM)</td>
			<td>Life Technologies</td>
			<td>11995-073</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Cellgro</td>
			<td>35-010-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl methanesulfonate (EMS)</td>
			<td>Sigma</td>
			<td>M0880</td>
			<td></td>
		</tr>
		<tr>
			<td>Cyclohexamide</td>
			<td>Sigma</td>
			<td>C4859-1ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Gentamicin</td>
			<td>Life Technologies</td>
			<td>15750-060</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline (PBS)</td>
			<td>Life Technologies</td>
			<td>14190-144</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline (PBS) solution with 0.493 mM MgCl2 and 0.901 mM CaCl2 (PBS+MgCl2/CaCl2)</td>
			<td>Life Technologies</td>
			<td>14040-133</td>
			<td></td>
		</tr>
		<tr>
			<td>1 M NaOH</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>5x SPG buffer (1.25 M sucrose, 50 mM sodium phosphate, 25 mM glutamic acid)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SPG buffer (0.25 M sucrose, 10 mM sodium phosphate, 5 mM glutamic acid)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Water (sterile, tissue culture grade)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2x DMEM (prepared from powder, buffered with 7.4 g/L Sodium Bicarbonate</td>
			<td>Sigma</td>
			<td>D7777</td>
			<td></td>
		</tr>
		<tr>
			<td>Nonessential amino acids (NEAA)</td>
			<td>Life Technologies</td>
			<td>11140-050</td>
			<td></td>
		</tr>
		<tr>
			<td>1.2% GTG Agarose , autoclaved</td>
			<td>Lonzo</td>
			<td>50070</td>
			<td></td>
		</tr>
		<tr>
			<td>Genomic DNA purification kits</td>
			<td>Qiagen</td>
			<td>69504</td>
			<td></td>
		</tr>
		<tr>
			<td>DNAzol</td>
			<td>Life Technologies</td>
			<td>10503-027</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol (molecular biology grade)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>8 mM NaOH</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0.1 M HEPES ( 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>25 cm2 tissue culture flasks (T25 flasks)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6-well tissue culture plates</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>12-well tissue culture plates</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>96-well tissue culture plates</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Chemical safety hood</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Biological safety hood</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#62;Centrifuge and adaptors for spinning tissue plates</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#62;Dissection microscope</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorometer (Qubit)</td>
			<td>Invitrogen</td>
			<td>Q32866</td>
			<td></td>
		</tr>
		<tr>
			<td>Adaptive Focused Acoustics S220 instrument</td>
			<td>Covaris</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

forward genetic approaches in chlamydia trachomatis

الكلاميديا، العامل المسبب للمرض من الأمراض التي تنتقل عن طريق الاتصال الجنسي والتهابات العين، لا تزال تتسم سيئة بسبب استعصاء الرامية إلى التحول التجريبية مع الحمض النووي المؤتلف. وضعنا نهجا لإجراء تحليل وراثي في C. المتدثرة على الرغم من عدم وجود الأدوات الوراثية الجزيئية. ينطوي على طريقتنا: أنا) الطفرات الكيميائية لتوليد بسرعة مكتبات شاملة من المسوخ وراثيا محددة مع الظواهر متميزة؛ الثاني) كامل تسلسل الجينوم (WGS) لتعيين الآفات الوراثية الكامنة وإيجاد الارتباط بين الجين المتحور (ق) و. النمط الظاهري المشتركة؛ الثالث) توليد سلالات المؤتلف من خلال المشاركة في إصابة خلايا الثدييات مع البكتيريا نوع متحولة والبرية. وفقا لذلك، كنا قادرين على إقامة علاقات سببية بين الأنماط الجينية والظواهر. اقتران كيميائيا التي يسببها اختلاف الجينات والفريق العامل المعني بالحالات في إنشاء جمعيات الوراثي، النمط الظاهري المتلازم شوتكون قابلة للتطبيق على نطاق واسع LD إلى قائمة كبيرة من الكائنات الحية الدقيقة طبيا وبيئيا هاما المستعصية حاليا للتحليل الجيني.

التعرض لالمغير يؤدي إلى مشتملات التي تظهر خالية من البكتيريا، يفترض أن يعود إلى موت الخلايا البكتيرية. عادة، سوف ضرب مصلي LGV-L2 ليز الخلايا المصابة تماما في غضون 48 ساعة إصابة آخر، ولكن العلاج مع المطفرة يمكن أن تمتد هذه الدورة ل&gt; 90 ساعة. ومن المتوقع لاسترداد ما يقرب من...

Watch this Scientific Journal Video about Forward Genetic Approaches in Chlamydia trachomatis at JoVE.com

Forward Genetic Approaches in Chlamydia trachomatis

نحن تصف منهجية لإجراء تحليل وراثي في الكلاميديا ​​يعتمد على الطفرات الكيميائية وكامل تسلسل الجينوم. وبالإضافة إلى ذلك، يوصف نظام لتبادل الحمض النووي داخل الخلايا المصابة التي يمكن استخدامها لرسم الخرائط الوراثية. قد تكون هذه الطريقة المطبقة على نطاق واسع لأنظمة الميكروبية التي تفتقر إلى نظم التحول والأدوات الوراثية الجزيئية.

النهج الوراثية إلى الأمام في<em&gt; الكلاميديا ​​المتدثرة</em

Chlamydia trachomatis, the etiological agent of sexually transmitted diseases and ocular infections, remains poorly characterized due to its ...

forward-genetic-approaches-in-chlamydia-trachomatis

Research

JoVE Journal

Immunology and Infection

Forward Genetic Approaches in Chlamydia trachomatis

A Genetic Screen to Isolate Toxoplasma gondii Host-cell Egress Mutants

The widespread, obligate intracellular, protozoan parasite Toxoplasma gondii causes opportunistic disease in immuno-compromised patients and causes birth defects upon congenital infection. The lytic replication cycle is characterized by three stages: 1. active invasion of a nucleated host cell; 2. replication inside the host cell; 3. active egress from the host cell. The mechanism of egress is increasingly being appreciated as a unique, highly regulated process, which is still poorly understood at the molecular level. The signaling pathways underlying egress have been characterized through the use of pharmacological agents acting on different aspects of the pathways1-5. As such, several independent triggers of egress have been identified which all converge on the release of intracellular Ca2+, a signal that is also critical for host cell invasion6-8. This insight informed a candidate gene approach which led to the identification of plant like calcium dependent protein kinase (CDPK) involved in egress9. In addition, several recent breakthroughs in understanding egress have been made using (chemical) genetic approaches10-12. To combine the wealth of pharmacological information with the increasing genetic accessibility of Toxoplasma we recently established a screen permitting the enrichment for parasite mutants with a defect in host cell egress13. Although chemical mutagenesis using N-ethyl-N-nitrosourea (ENU) or ethyl methanesulfonate (EMS) has been used for decades in the study of Toxoplasma biology11,14,15, only recently has genetic mapping of mutations underlying the phenotypes become routine16-18. Furthermore, by generating temperature-sensitive mutants, essential processes can be dissected and the underlying genes directly identified. These mutants behave as wild-type under the permissive temperature (35 &deg;C), but fail to proliferate at the restrictive temperature (40 &deg;C) as a result of the mutation in question. Here we illustrate a new phenotypic screening method to isolate mutants with a temperature-sensitive egress phenotype13. The challenge for egress screens is to separate egressed from non-egressed parasites, which is complicated by fast re-invasion and general stickiness of the parasites to host cells. A previously established egress screen was based on a cumbersome series of biotinylation steps to separate intracellular from extracellular parasites11. This method also did not generate conditional mutants resulting in weak phenotypes. The method described here overcomes the strong attachment of egressing parasites by including a glycan competitor, dextran sulfate (DS), that prevents parasites from sticking to the host cell19. Moreover, extracellular parasites are specifically killed off by pyrrolidine dithiocarbamate (PDTC), which leaves intracellular parasites unharmed20. Therefore, with a new phenotypic screen to specifically isolate parasite mutants with defects in induced egress, the power of genetics can now be fully deployed to unravel the molecular mechanisms underlying host cell egress.

A Genetic Screen to Isolate Toxoplasma gondii Host-cell Egress Mutants

Forward genetics is a powerful method to unravel the molecular level of how Toxoplasma egresses from its host cell. Protocols are provided to chemically mutagenize parasites, enrich for mutants with defects in induced egress, and validate the phenotype of cloned mutants.

شاشة الوراثية لعزل التوكسوبلازما جوندياي المسوخ الخروج المضيف الخلية

The widespread, obligate intracellular, protozoan parasite Toxoplasma gondii causes opportunistic disease in immuno-compromised patients and causes birth ...

Genetic Manipulation in &Delta;ku80 Strains for Functional Genomic Analysis of Toxoplasma gondii

Targeted genetic manipulation using homologous recombination is the method of choice for functional genomic analysis to obtain a detailed view of gene function and phenotype(s). The development of mutant strains with targeted gene deletions, targeted mutations, complemented gene function, and/or tagged genes provides powerful strategies to address gene function, particularly if these genetic manipulations can be efficiently targeted to the gene locus of interest using integration mediated by double cross over homologous recombination.
Due to very high rates of nonhomologous recombination, functional genomic analysis of Toxoplasma gondii has been previously limited by the absence of efficient methods for targeting gene deletions and gene replacements to specific genetic loci. Recently, we abolished the major pathway of nonhomologous recombination in type I and type II strains of T. gondii by deleting the gene encoding the KU80 protein1,2. The &Delta;ku80 strains behave normally during tachyzoite (acute) and bradyzoite (chronic) stages in vitro and in vivo and exhibit essentially a 100% frequency of homologous recombination. The &Delta;ku80 strains make functional genomic studies feasible on the single gene as well as on the genome scale1-4.
Here, we report methods for using type I and type II &Delta;ku80&Delta;hxgprt strains to advance gene targeting approaches in T. gondii. We outline efficient methods for generating gene deletions, gene replacements, and tagged genes by targeted insertion or deletion of the hypoxanthine-xanthine-guanine phosphoribosyltransferase (HXGPRT) selectable marker. The described gene targeting protocol can be used in a variety of ways in &Delta;ku80 strains to advance functional analysis of the parasite genome and to develop single strains that carry multiple targeted genetic manipulations. The application of this genetic method and subsequent phenotypic assays will reveal fundamental and unique aspects of the biology of T. gondii and related significant human pathogens that cause malaria (Plasmodium sp.) and cryptosporidiosis (Cryptosporidium).

Genetic Manipulation in &lt;em&gt;&amp;Delta;ku80&lt;/em&gt; Strains for Functional Genomic Analysis of &lt;em&gt;Toxoplasma gondii&lt;/em&gt;

Here we report a method for using type I and type II &Delta;ku80 strains of Toxoplasma gondii to efficiently generate targeted gene deletions and gene replacements for functional genomic analysis.

التلاعب الجيني في<em&gt; Δku80</em&gt; سلالات لتحليل الجينوم الوظيفي لل<em&gt; التوكسوبلازما جوندياي</em

Targeted genetic manipulation using homologous recombination is the method of choice for functional genomic analysis to obtain a detailed view of gene ...

VIGS-Mediated Forward Genetics Screening for Identification of Genes Involved in Nonhost Resistance

Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important for developing durable disease-resistant plants against wide range of pathogens. Virus-induced gene silencing (VIGS)-based forward genetics screening is a useful approach for identification of plant defense genes imparting nonhost resistance. Tobacco rattle virus (TRV)-based VIGS vector is the most efficient VIGS vector to date and has been efficiently used to silence endogenous target genes in Nicotiana benthamiana.

	In this manuscript, we demonstrate a forward genetics screening approach for silencing of individual clones from a cDNA library in N. benthamiana and assessing the response of gene silenced plants for compromised nonhost resistance against nonhost pathogens, Pseudomonas syringae pv. tomato T1, P. syringae pv. glycinea, and X. campestris pv. vesicatoria. These bacterial pathogens are engineered to express GFPuv protein and their green fluorescing colonies can be seen by naked eye under UV light in the nonhost pathogen inoculated plants if the silenced target gene is involved in imparting nonhost resistance. This facilitates reliable and faster identification of gene silenced plants susceptible to nonhost pathogens. Further, promising candidate gene information can be known by sequencing the plant gene insert in TRV vector. Here we demonstrate the high throughput capability of VIGS-mediated forward genetics to identify genes involved in nonhost resistance. Approximately, 100 cDNAs can be individually silenced in about two to three weeks and their relevance in nonhost resistance against several nonhost bacterial pathogens can be studied in a week thereafter. In this manuscript, we enumerate the detailed steps involved in this screening. VIGS-mediated forward genetics screening approach can be extended not only to identifying genes involved in nonhost resistance but also to studying genes imparting several biotic and abiotic stress tolerances in various plant species.

Virus-induced gene silencing is an useful tool for identifying genes involved in nonhost resistance of plants. We demonstrate the use of bacterial pathogens expressing GFPuv in identifying gene silenced plants susceptible to nonhost pathogens. This approach is easy, fast and facilitates large scale screening and similar protocol can be applied to studying various other plant-microbe interactions.


	Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important ...

Discovery of New Intracellular Pathogens by Amoebal Coculture and Amoebal Enrichment Approaches

Intracellular pathogens such as legionella, mycobacteria and Chlamydia-like organisms are difficult to isolate because they often grow poorly or not at all on selective media that are usually used to cultivate bacteria. For this reason, many of these pathogens were discovered only recently or following important outbreaks. These pathogens are often associated with amoebae, which serve as host-cell and allow the survival and growth of the bacteria. We intend here to provide a demonstration of two techniques that allow isolation and characterization of intracellular pathogens present in clinical or environmental samples: the amoebal coculture and the amoebal enrichment. Amoebal coculture allows recovery of intracellular bacteria by inoculating the investigated sample onto an amoebal lawn that can be infected and lysed by the intracellular bacteria present in the sample. Amoebal enrichment allows recovery of amoebae present in a clinical or environmental sample. This can lead to discovery of new amoebal species but also of new intracellular bacteria growing specifically in these amoebae. Together, these two techniques help to discover new intracellular bacteria able to grow in amoebae. Because of their ability to infect amoebae and resist phagocytosis, these intracellular bacteria might also escape phagocytosis by macrophages and thus, be pathogenic for higher eukaryotes.

Amoebal coculture is a cell culture system using adherent amoebae to selectively grow intracellular pathogens able to resist phagocytic cells such as amoebae and macrophages. It thus represents a key tool to discover new infectious agents. Amoebal enrichment allows discovery of new amoebal species and of their specific intracellular bacteria.

اكتشاف جديد بين الخلايا مسببات الأمراض عن طريق Amoebal Coculture والمناهج Amoebal التخصيب

Intracellular pathogens such as legionella, mycobacteria and Chlamydia-like organisms are difficult to isolate because they often grow poorly or not at ...

Using Fluorescent Proteins to Visualize and Quantitate Chlamydia Vacuole Growth Dynamics in Living Cells

The obligate intracellular bacterium Chlamydia elicits a great burden on global public health. C.&#160;trachomatis is the leading bacterial cause of sexually transmitted infection and also the primary cause of preventable blindness in the world. An essential determinant for successful infection of host cells by Chlamydia is the bacterium's ability to manipulate host cell signaling from within a novel, vacuolar compartment called the inclusion. From within the inclusion, Chlamydia acquire nutrients required for their 2-3 day developmental growth, and they additionally secrete a panel of effector proteins onto the cytosolic face of the vacuole membrane and into the host cytosol. Gaps in our understanding of Chlamydia biology, however, present significant challenges for visualizing and analyzing this intracellular compartment. Recently, a reverse-imaging strategy for visualizing the inclusion using GFP expressing host cells was described. This approach rationally exploits the intrinsic impermeability of the inclusion membrane to large molecules such as GFP. In this work, we describe how GFP- or mCherry-expressing host cells are generated for subsequent visualization of chlamydial inclusions. Furthermore, this method is shown to effectively substitute for costly antibody-based enumeration methods, can be used in tandem with other fluorescent labels, such as GFP-expressing Chlamydia, and can be exploited to derive key quantitative data about inclusion membrane growth from a range of Chlamydia species and strains.

Using Fluorescent Proteins to Visualize and Quantitate Chlamydia Vacuole Growth Dynamics in Living Cells

A live cell fluorescent protein based method for illuminating cellular vacuoles (inclusions) containing Chlamydia is described. This strategy enables rapid, automated determination of Chlamydia infectivity in samples and can be used to quantitatively investigate inclusion growth dynamics.

باستخدام نيون البروتينات إلى تصور وQuantitate<em&gt; الكلاميديا</em&gt; فجوة النمو حيوية في الخلايا الحية

The obligate intracellular bacterium Chlamydia elicits a great burden on global public health. C.&#160;trachomatis is the leading bacterial cause of ...

Forward Genetics Screens Using Macrophages to Identify Toxoplasma gondii Genes Important for Resistance to IFN-&#947;-Dependent Cell Autonomous Immunity

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular protozoan pathogen. The parasite invades and replicates within virtually any warm blooded vertebrate cell type. During parasite invasion of a host cell, the parasite creates a parasitophorous vacuole (PV) that originates from the host cell membrane independent of phagocytosis within which the parasite replicates. While IFN-dependent-innate and cell mediated immunity is important for eventual control of infection, innate immune cells, including neutrophils, monocytes and dendritic cells, can also serve as vehicles for systemic dissemination of the parasite early in infection. An approach is described that utilizes the host innate immune response, in this case macrophages, in a forward genetic screen to identify parasite mutants with a fitness defect in infected macrophages following activation but normal invasion and replication in na&#239;ve macrophages. Thus, the screen isolates parasite mutants that have a specific defect in their ability to resist the effects of macrophage activation. The paper describes two broad phenotypes of mutant parasites following activation of infected macrophages: parasite stasis versus parasite degradation, often in amorphous vacuoles. The parasite mutants are then analyzed to identify the responsible parasite genes specifically important for resistance to induced mediators of cell autonomous immunity. The paper presents a general approach for the forward genetics screen that, in theory, can be modified to target parasite genes important for resistance to specific antimicrobial mediators. It also describes an approach to evaluate the specific macrophage antimicrobial mediators to which the parasite mutant is susceptible. Activation of infected macrophages can also promote parasite differentiation from the tachyzoite to bradyzoite stage that maintains chronic infection. Therefore, methodology is presented to evaluate the importance of the identified parasite gene to establishment of chronic infection.

Forward Genetics Screens Using Macrophages to Identify Toxoplasma gondii Genes Important for Resistance to IFN-&amp;#947;-Dependent Cell Autonomous Immunity

Forward genetics is a powerful approach to identify genes in intracellular pathogens important for resistance to cell autonomous immunity. The current approach uses innate immune cells, specifically macrophages, to identify novel Toxoplasma gondii genes important for immune evasion.

الى الامام علم الوراثة شاشات طريق الضامة لتحديد<em&gt; التوكسوبلازما</em&gt; الجينات هامة الحصانة الذاتية للمقاومة إلى الإنترفيرون γ التي تعتمد على خلية

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular protozoan pathogen. The parasite invades and replicates within ...

Utilizing the Antigen Capsid-Incorporation Strategy for the Development of Adenovirus Serotype 5-Vectored Vaccine Approaches

Adenovirus serotype 5 (Ad5) has been extensively modified with traditional transgene methods for the vaccine development. The reduced efficacies of these traditionally modified Ad5 vectors in clinical trials could be primarily correlated with Ad5 pre-existing immunity (PEI) among the majority of the population. To promote Ad5-vectored vaccine development by solving the concern of Ad5 PEI, the innovative Antigen Capsid-Incorporation strategy has been employed. By merit of this strategy, Ad5-vectored we first constructed the hexon shuttle plasmid HVR1-KWAS-HVR5-His6/pH5S by subcloning the hypervariable region (HVR) 1 of hexon into a previously constructed shuttle plasmid HVR5-His6/pH5S, which had His6 tag incorporated into the HVR5. This HVR1 DNA fragment containing a HIV epitope ELDKWAS was synthesized. HVR1-KWAS-HVR5-His6/pH5S was then linearized and co-transformed with linearized backbone plasmid pAd5/&#8710;H5 (GL) , for homologous recombination. This recombined plasmid pAd5/H5-HVR1-KWAS-HVR5-His6 was transfected into cells to generate the viral vector Ad5/H5-HVR1-KWAS-HVR5-His6. This vector was validated to have qualitative fitness indicated by viral physical titer (VP/ml), infectious titer (IP/ml) and corresponding VP/IP ratio. Both the HIV epitope and His6 tag were surface-exposed on the Ad5 capsid, and retained epitope-specific antigenicity of their own. A neutralization assay indicated the ability of this divalent vector to circumvent neutralization by Ad5-positive sera in vitro. Mice immunization demonstrated the generation of robust humoral immunity specific to the HIV epitope and His6. This proof-of-principle study suggested that the protocol associated with the Antigen Capsid-Incorporation strategy could be feasibly utilized for the generation of Ad5-vectored vaccines by modifying different capsid proteins. This protocol could even be further modified for the generation of rare-serotype adenovirus-vectored vaccines.

Here, we present a protocol to generate a proof-of-principle divalent adenovirus type 5 (Ad5) vector Ad5/H5-HVR1-KWAS-HVR5-His6 by utilizing the Antigen Capsid-Incorporation strategy. This vector was demonstrated to exhibit qualitative fitness, the capability to escape Ad5-positive sera in vitro, and the antigenicity as well as immunogenicity to the incorporated antigens.

استخدام استراتيجية قفيصة التأسيس Antigen ل تطوير المناهج اتش المصلي 5 تنقلها لقاح

Adenovirus serotype 5 (Ad5) has been extensively modified with traditional transgene methods for the vaccine development. The reduced efficacies of these ...

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Current investigations into phage-host interactions are dependent on extrapolating knowledge from (meta)genomes. Interestingly, 60 - 95% of all phage sequences share no homology to current annotated proteins. As a result, a large proportion of phage genes are annotated as hypothetical. This reality heavily affects the annotation of both structural and auxiliary metabolic genes. Here we present phenomic methods designed to capture the physiological response(s) of a selected host during expression of one of these unknown phage genes. Multi-phenotype Assay Plates (MAPs) are used to monitor the diversity of host substrate utilization and subsequent biomass formation, while metabolomics provides bi-product analysis by monitoring metabolite abundance and diversity. Both tools are used simultaneously to provide a phenotypic profile associated with expression of a single putative phage open reading frame (ORF). Representative results for both methods are compared, highlighting the phenotypic profile differences of a host carrying either putative structural or metabolic phage genes. In addition, the visualization techniques and high throughput computational pipelines that facilitated experimental analysis are presented.

Here, we present phenomic approaches for the functional characterization of putative phage genes. Techniques include a developed assay capable of monitoring host anabolic metabolism, the Multi-phenotype Assay Plates (MAPs), in addition to the established method of metabolomics, capable of measuring effects to catabolic metabolism.

Phenomics فج: مقاربات الفسيولوجية لتوصيف رواية الفيروسية البروتينات

Current investigations into phage-host interactions are dependent on extrapolating knowledge from (meta)genomes. Interestingly, 60 - 95% of all phage ...

A Simple Red Blood Cell Lysis Method for the Establishment of B Lymphoblastoid Cell Lines

A number of methods exist for the transformation of B lymphocytes by the Epstein Barr virus in vitro into immortalized cell lines. We have developed a new method with a powerful and simple strategy for the establishment of B-LCLs, the red blood cell lysis method. This method simplified the PBMC separation procedure with red blood cell removal, and used as little as 0.5 mL of whole blood for establishing EBV-immortalized cell lines, which can proliferate to large cell numbers in a relatively short amount time with a 100% success rate. The method is simple, reliable, time saving, and applicable to treating a large number of the clinical samples.

A simple red blood cell lysis method for establishing B-LCLs was developed with high immortalization efficiency, requiring a small amount of blood and saving time from initiation to cryopreservation.

وبسيط خلية الدم الحمراء تحلل طريقة لإنشاء خطوط الخلايا B Lymphoblastoid

A number of methods exist for the transformation of B lymphocytes by the Epstein Barr virus in vitro into immortalized cell lines. We have developed a new ...

An Efficient and Simple Method to Establish NK and T Cell Lines from Patients with Chronic Active Epstein-Barr Virus Infection

A number of methods have been described to establish NK/T cell lines from patients with lymphoma or lymphoproliferative syndrome. These methods employed feeder cells, purified NK or T cells with as much as 10 mL of blood, or a high-dose of IL-2. This study presents a new method with a powerful and simple strategy to establish NK and T cell lines by culturing the peripheral blood mononuclear cells (PBMC) with the addition of recombinant human IL-2 (rhIL-2), and uses as little as 2 mL of whole blood. The cells can proliferate quickly in two weeks and be maintained for more than 3 months. With this method, 7 NK or T cell lines have been established with a high success rate. This method is simple, reliable, and applicable to establishing cell lines from more cases of CAEBV or NK/T cell lymphoma.

A simple method for obtaining NK and T cell clones from CAEBV patients was developed with high efficiency, a small amount of peripheral blood, and a low-dose of IL-2.

طريقة فعالة وبسيطة وضع ناغورني كاراباخ وخطوط الخلايا T من المرضى المصابين بالعدوى المزمنة النشطة فيروس ابشتاين-بار

A number of methods have been described to establish NK/T cell lines from patients with lymphoma or lymphoproliferative syndrome. These methods employed ...