Special thanks to Dr. Peter Bradley for the antibody to detect the T. gondii mitochondria. The work was supported by National Institute of Health Grants AI072028 and AI107431 to D.G.M and a generous donation to New York Medical College for the study of tropical medicine.

The authors have no competing financial interests.

설명 된 프로토콜은 뮤린 골수 유래 대 식세포를 분리 T. 순방향 유전학의 활성화를 사용하여 비 편파 접근법을 제공 자신의 능력에 결함이와 포자충 돌연변이 감염된 대 식세포의 활성화를 생존. 돌연변이 다음 식세포 활성화의 표현형은 일반적으로 두 가지 범주 중 하나에 해당 : 1) 기생충은 그대로 나타나지만 PV 당 1 기생을 넘어 복제하는 데 실패; 2) 기생충이 저하 될 넓고...

톡소 포자충 (T. 포자충)는 의무적 인 세포, 원 충성 병원체이다. 이 톡소 플라즈마 증의 원인균, 면역 개인의 건강 위험이 있습니다. 또한 포자충과 원 포자충 속을 포함하여 인간을 감염 다른 apicomplexan 병원균의 모델 시스템입니다. 톡소 플라즈마 증은 가장 일반적으로 기생충의 bradyzoite 또는 oocyst 단계에 오염 된 음식이나 물을 섭취을 통해 획득된다. 섭취시,이 단계는 숙주 세포 내에서 복제하고 체계적으로 유포 기생충의 tachyzoite 단계로 변환합니다. T 세포, IFN-γ와, 낮은 정도, 산화 질소 1-4, 감염의 조절에 중요하지만 tachyzoites의 비율로, 병을 제거 할 수없는 조직 포낭 내에서 보호된다 bradyzoite 스테이지로 변환 수명이 긴 만성 감염의 결과. 사실, 어떤 치료제는 만성 낭종의에 효과가없는질병의 다케. 심한 톡소 플라즈마 증은 기본 및 급성 감염의 신속 복제 tachyzoite 단계 특성으로 다시 변환 기생충의 bradyzoite 단계로 인해 지속적인 감염의 재 활성화에 가장 많다. 선천성 면역 반응의면에서 이른 생존 기생충 충분한 기생충 번호에 도달 할뿐만 아니라 만성 감염의 확립을 가능하게하기 위해, 말초 부위에 도달 할 수 있도록하는 것이 중요하다. T. 포자충 가능성 복제 및 감염의 조기 보급 할 수있는 능력에 기여하는 숙주 방어 메커니즘을 방해하는 전략을 진화했다. 첫째, T. 포자충 다른 세포 내 병원체에 비해 5-9 숙주 세포 내 이입 및 exocytic 프로세스와 크게 편석 기생충 침윤 동안 고유 PV를 형성한다. 또한, 모든 성공적인 세포 내 병원균의 T. 같은 포자충은 f를 허용 환경을 조성하기 위해 숙주 세포를 수정또는 성장. 이것은 세포 활성화 10-15 조절에 중요 포함한 숙주 세포 전사 인자를 변경하여 재 프로그래밍 숙주 세포의 유전자 발현을 포함한다. ROP16 16-19 GRA15 20 GRA16 21, 22는 모두 GRA24 T. 감염된 숙주 세포를 전사 캐스케이드 반응을 조절하고 세포 시그널링에 중요한 것으로 밝혀졌다 포자충. 별개의 표현형과 기생충 변종 사이의 유전 십자가를 사용하여 최근의 연구는 면역 관련 GTP 아제 (IRGs) 16,19,23-26의 회피를 포함하여 기생충 유전자형에 의존하는 특성을 기초 기생충 유전자를 식별하는 매우 생산되고있다. 매우 독성이 강한 유형 I 유전자형이 쥐 IRGs을 회피 메커니즘을 진화하는 동안 마우스에 면역 관련 GTP 아제 (IRGs)는 유형 II의 제어 및 기생충의 III 유전자형을 위해 중요하다. 그러나, 기생충 항균 미디어를 회피하는 메커니즘을 진화 한 것이 분명하다이러한 메커니즘의 일부 IRGs과 그 외에 TORS는 기생충 유전자형 (27, 28)에 걸쳐 보존 할 수있다. 또한, 약간은 T.에 대한 세포 자율 면역의 중요한 매개체에 대해 알려진 인간의 톡소 플라즈마 증 동안 포자충. tachyzoite 또한 호스트 면역 반응에 의해 유발 될 수있는 변환을 bradyzoite하는 동안 셀 자율 면역 매개 물질에 대한 저항성에 중요한 기생충 유전자는 생존을 위해 중요 할 수있다. 예를 들어, 높은 수준의 질소 산화물이 감염된 대 식세포 기생충 복제를 억제 할뿐만 아니라 생산 낭종 30-32 변환을 초래하는 bradyzoite tachyzoite을 자극 할 수있다. ToxoDB는 T.위한 기능 게놈 데이터베이스입니다 포자충 그 지역 사회 주석을 포함한 출판되지 않은 게놈 규모의 데이터 시퀀스 기생충 게놈에 대한 정보와 액세스를 제공하는 측면에서 필드의 중요한 자원으로 기능, 유전자 특급<html> ression 및 단백체 데이터 (33). 많은 충성 병원체와 마찬가지로, 게놈의 대부분이 잠재적 인 기능에 대한 통찰력을 제공하기 위해 유전자 상 동성을 기반으로 사용할 수없는 정보와 가상의 유전자로 구성되어 있습니다. 따라서, 앞으로 유전자는 면역 회피, 낭종 변환 및 기생충 병인뿐만 아니라 별개의 발달 단계 사이의 변환을위한 중요한 다른 기능에 중요한 새로운 기생충 유전자를 식별 할 수있는 강력한 도구입니다. 순방향 유전학의 추가적인 장점은 면역 회피 및 포낭 형성 포함한 병인 특정 작업에 중요한 유전자로 기생충 심문 비교적 비 편향된 방식으로 사용될 수 있다는 점이다. 돌연변이 프로파일 링을위한 차세대 시퀀싱 최근 개선은 화학에서 삽입 모두 돌연변이 유발 34 ~ 37를 사용하여 앞으로 유전학 연구의 책임 기생충 유전자를 식별하기위한 선택의 방법을 만들었습니다. ntent은 &quot;&gt; 그것은 특히 또한 저항 낭종 단계에 활성화 될 수 것들.이 목표를 향해, 시험관 쥐의 기생충에 대한 세포 자율 면역 메커니즘의 효율성을 향상시키기 위해 이용 될 수있다 T. 포자충의 취약점을 파악하는 것이 중요하다 대 식세포 감염 및 활성화 모델을 구체적으로 순진한 대 식세포에 감염된 대 식세포의 활성화가 아닌 다음 T.의 포자충 체력을 손상 기생충 돌연변이를 확인하기 위해 개발되었다.이 대 식세포 화면에 순서대로 T. 포자충에서 삽입 돌연변이 체의 라이브러리를 심문하기 위해 사용되었다 궁극적으로 산화 질소 (27, 28)에 대한 내성을 위해 중요 T. 포자충 유전자를 확인한다. 감염된 대 식세포 산화 질소 특히 현저한 감도의 활성화에 장애가 저항 T. 포자충 돌연변이 패널의 분리를 식별하기 위해 화면의 유용성을 입증 저항에 대한 중요한 기생충 유전자뮤린 IRGs 28에 기재된 저항기구 이외 셀 자율 면역 매개체이다. 삽입 성 돌연변이 유발 이론 랜덤 기생충 각 클론의 돌연변이 및 돌연변이의 위치의 식별을 용이하게 제한된 수를 생성하는 관점에서 화학적 돌연변이 유발에 비해 많은 장점을 갖는다. 그러나, T.에서 플라스미드 삽입의 게놈 사이트를 식별합니다 포자충 삽입 성 변이체는, 실제로는, 많은 경우에 37 의외로 어려웠다. 유전자 내로 플라스미드의 삽입은 일반적으로 단일 염기 변화를 초래 화학적 돌연변이 대조적으로 유전자의 기능을 방해하기 쉽다. 그것은 다수의 단일 염기 다형성을 생성하지만, 화학적 돌연변이 유발 N 에틸 -N- 니트로 소 우레아 (ENU) 또는 ethylmethane 설포 네이트 (EMS) 중 하나와 (삽입 성 돌연변이 유발에 비해 기생충 게놈의 큰 부분을 분석 할 수있는 증가 된 능력을 제공 할 수있다 돌연변이 (34) 당 10 -100)로 추정38. 또한, 전체 게놈 프로파일 최근 발전은 가능한 돌연변이 기생충 34,38의 표현형에 책임 식별 가능성의 후보 유전자를 동정하는 차세대 시퀀싱을 사용하도록했다. 상관없이 돌연변이 유발 접근법 식세포 활성화에 저항 기생충 유전자의 역할을 확인 궁극적 분자 코흐의 공리를 충족 유전자 결실 및 보완이 필요하다. 기생충 및 대식구 모두의 유전자 조작에 의한 유전자의 기능을 절개하는 능력은 T. 앞으로 유전학 통해 식별 된 유전자의 많은만큼 중요 포자충,뿐만 아니라 다른 병원체는 아직 공지 기능없이 다른 단백질 서열 상 동성이 거의 가설 유전자로 특징 지어진다. 현재 용지는 돌연변이 유전자의 파괴는 공지 또는 내성에 중요한 것인지 식별​​ 할 수있는 일반적인 방법을 설명셀 자율 면역 알 수없는 중재자. 숙주 미생물 인자 초기 분석은 야생형 및 유도 성 산화 질소 합성 효소 (iNOS의) GP-91 phox (NADPH 옥시 다제)에서 특정 유전자의 결실로 그 대 야생형 마우스에서 대 식세포의 돌연변이 기생충의 생존을 평가함으로써 수행되고 특정 면역 관련 GTP 아제 (IRGs). 확인 된 기생충 유전자가 산화 질소, 활성 산소 중간체 또는 면역 관련 GTP 아제 (28)을 각각 또는 알 수없는 면역 메커니즘이 관련된 경우에 대한 저항성에 중요한 경우를 결정합니다. 현재의 프로토콜에 기재된 IFN-γ와 LPS 모두 감염된 대 식세포의 활성화는, 주로 일산화 질소 (28)의 저항에 중요한 기생충 유전자의 분리 결과. 마크로파지 활성화의 부재 하에서 산화 질소 유도되는 약물의 사용은 (산화 질소 공여체) 식별 유전자의 대부분이 재 중요한 것이 확인산화 질소보다는 대 식세포 활성화 (28)와 관련된 추가 매개과 콘서트에서 산화 질소에 sistance. 하나, 둘, 시험관에 감염된 골수 유래 대 식세포의 활성화를 다음과 피트니스 결함과 기생충 돌연변이를 분리하기위한 앞으로 유전학 화면을 설명하는 단계. 하나 기생충 복제를 감소 시키지만, 완전 야생형 T.의 복제를 저해하지 않는 대 식세포 활성화를 위해 사용 된 실험적 IFN- γ와 LPS의 투여 량을 결정하기 위해 용량 적정 분석을 설명 스텝 기생충 돌연변이 라이브러리의 제작에 사용되는 모 균주 포자충. 두 번째 단계는 96 웰 플레이트에서 대 식세포의 돌연변이 클론의 앞으로 유전 화면을 설명합니다. 세 번째 단계는 각 돌연변이에 결함이 기생충의 생존에 영향을 미치는지, 복제를 평가하고 96 웰 플레이트의 화면에서 식별 된 각 돌연변이의 표현형을 확인하는 방법을 설명,대 식세포의 활성화에 응답 또는 낭종 생산. 네 단계는 돌연변이 기생충은 특히 민감되는 면역 매개체를 식별하기 위해 특정 항균 통로에 결실 된 마우스 골수 유래 대 식세포를 사용하는 방법을 설명한다. 5 단계는 감염된 쥐의 뇌에 낭종 생산에 의해 평가 등의 기생충 돌연변이는 또한 생체 기전에 대한 손상 여부를 확인하는 방법을 설명합니다.

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			&#38;searchType=PROD&#38;hasPromo=0</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hyclone Hanks BSS</td>
			<td>Thermo</td>
			<td>SH3003002</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
			Id=29104&#38;productId=3064595&#38;dis 
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		<tr height="21">
			<td height="21" style="height:21px;">LPS</td>
			<td>LIST biologicals</td>
			<td align="right">201</td>
			<td>http://www.listlabs.com/products-tech.php?cat_id=4&#38;product_id=81&#38;keywords 
			=LPS_from_%3Cem%3EEscherichia_coli%3C/em%3E_O111:B4</td>
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			<td height="21" style="height:21px;">IFN-g</td>
			<td>Pepro Tech Inc</td>
			<td>50-813-664</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?itemdetail=&#39;item&#39;&#38;storeId=10652&#38; 
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			<td height="21" style="height:21px;">Chamber slides</td>
			<td>Thermo</td>
			<td align="right">177402</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
			Id=29104&#38;productId=2164545&#38;dis 
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		<tr height="21">
			<td height="21" style="height:21px;">96-well optical plates</td>
			<td>Thermo</td>
			<td align="right">165306</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
			Id=29104&#38;productId=3010670&#38;dis 
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		<tr height="21">
			<td colspan="2" height="21" style="height:21px;">96-well tissue culture plates</td>
			<td></td>
			<td align="right">353072</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
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			<td colspan="2" height="21" style="height:21px;">Tissue culture flast T25</td>
			<td></td>
			<td align="right">156367</td>
			<td>https://www.fishersci.com/ecomm/servlet/fsproductdetail?storeId=10652&#38;productId=127039 
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		<tr height="21">
			<td colspan="2" height="21" style="height:21px;">Ted Pella EM grade formaldehyde</td>
			<td></td>
			<td align="right">18505</td>
			<td>http://www.tedpella.com/chemical_html/chem3.htm#anchor267712</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Triton X-100</td>
			<td>Fisher</td>
			<td>BP151</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
			Id=29104&#38;productId=3425922&#38;dis 
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		<tr height="21">
			<td height="21" style="height:21px;">Alexa 488 - protein conjugation kit</td>
			<td>Life Technologies</td>
			<td>A20181</td>
			<td>http://www.lifetechnologies.com/order/catalog/product/A10235</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">goat serum</td>
			<td>MP Biomedicals</td>
			<td>ICN19135680</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
			Id=29104&#38;productId=2133236&#38;dis 
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			=PROD&#38;hasPromo=0</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vectashield mounting media</td>
			<td>Vector Labs</td>
			<td>H1200</td>
			<td>https://www.vectorlabs.com/catalog.aspx?prodID=428</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FITC-conjugated dolichos</td>
			<td>Vector Labs</td>
			<td>FL-1031</td>
			<td>https://www.vectorlabs.com/catalog.aspx?prodID=188</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Antibody to LAMP1</td>
			<td colspan="2">Developmental Studies Hybridoma Bank</td>
			<td>http://dshb.biology.uiowa.edu/LAMP-1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LysoTracker</td>
			<td>Life Technologies</td>
			<td>L-7526</td>
			<td>https://www.lifetechnologies.com/order/catalog/product/L7526?ICID=search-product</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C57BL6 mice</td>
			<td>Jackson Laboratories</td>
			<td align="right">664</td>
			<td>http://jaxmice.jax.org/strain/000664.html</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">gp91 phox knock out mice</td>
			<td>Jackson Labaoratories</td>
			<td align="right">2365</td>
			<td>http://jaxmice.jax.org/strain/002365.html</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">iNOS knock out mice</td>
			<td>Jackson Laboratories</td>
			<td align="right">2609</td>
			<td>http://jaxmice.jax.org/strain/002609.html</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">sodium nitroprusside</td>
			<td>ACROS Organics</td>
			<td>AC21164-0250&#160;</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
			Id=29104&#38;productId=2627727&#38;dis 
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			PROD&#38;hasPromo=1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DETA NONOate</td>
			<td>ACROS Organics</td>
			<td>AC32865-0250</td>
			<td>https://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&#38;langId=-1&#38;catalog 
			Id=29104&#38;productId=2252389&#38;dis 
			type=0&#38;highlightProductsItemsFlag 
			=Y&#38;fromSearch=1&#38;searchType= 
			PROD&#38;hasPromo=1</td>
		</tr>
		<tr height="21">
			<td colspan="2" height="21" style="height:21px;">Monoclonal mouse anti-Toxoplasma gondii Ab</td>
			<td></td>
			<td>10T19A</td>
			<td>http://1degreebio.org/reagents/product/1069274/?qid=652947</td>
		</tr>
	</tbody>
</table>

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.

톡소 포자충은 순진 대 식세포에서 자유롭게 복제하고 6 ~ 12 시간이 기생충의 변형에 따라 사이에 두 배의 시간이 있습니다. (1)가 활성화 된 골수 유래 대 식세포 대 순진한 대표 기생충을 보여줍니다. 그림 2 HFF에서 기생충의 일반적인 형태를 보여줍니다 2, 4, 8, 16, 32 기생충 / PV에서 숙주 세포. 현재 프로토콜에서 기생충은 순진 대 식세포 침입 감염된 대 식세포에 ...

Watch this Scientific Journal Video about Forward Genetics Screens Using Macrophages to Identify Toxoplasma gondii Genes Important for Resistance to IFN-ÃŽÂ³-Dependent Cell Autonomous Immunity at JoVE

Forward Genetics Screens Using Macrophages to Identify Toxoplasma gondii Genes Important for Resistance to IFN-&#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.

앞으로 유전학 식별하는 대 식세포를 사용하여 화면<em&gt; 톡소 포자충</em&gt; 유전자 중요 저항이하는 IFN-γ 의존 세포 자치 내성

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

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

Unit 2

Population Genetics

Analyzing Gene Expression and Function

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11.0K 조회수.  New York Medical College. 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. 

비디오: Forward Genetics Screens Using Macrophages to Identify Toxoplasma gondii Genes Important for Resistance to IFN-γ-Dependent Cell Autonomous Immunity

Obtaining Highly Purified Toxoplasma gondii Oocysts by a Discontinuous Cesium Chloride Gradient

Toxoplasma gondii is an obligate intracellular protozoan pathogen that commonly infects humans. It is a well characterized apicomplexan associated with causing food- and water-borne disease outbreaks. The definitive host is the feline species where sexual replication occurs resulting in the development of the highly infectious and environmentally resistant oocyst. Infection occurs via ingestion of tissue cysts from contaminated meat or oocysts from soil or water. Infection is typically asymptomatic in healthy individuals, but results in a life-long latent infection that can reactivate causing toxoplasmic encephalitis and death if the individual becomes immunocompromised. Meat contaminated with T. gondii cysts have been the primary source of infection in Europe and the United States, but recent changes in animal management and husbandry practices and improved food handling and processing procedures have significantly reduced the prevalence of T. gondii cysts in meat1, 2. Nonetheless, seroprevalence in humans remains relatively high suggesting that exposure from oocyst contaminated soil or water is likely. Indeed, waterborne outbreaks of toxoplasmosis have been reported worldwide supporting the theory exposure to the environmental oocyst form poses a significant health risk3-5. To date, research on understanding the prevalence of T. gondii oocysts in the water and environment are limited due to the lack of tools to detect oocysts in the environment 5, 6. This is primarily due to the lack of efficient purification protocols for obtaining large numbers of highly purified T gondii oocysts from infected cats for research purposes. This study describes the development of a modified CsCl method that easily purifies T. gondii oocysts from feces of infected cats that are suitable for molecular biological and tissue culture manipulation7.

Obtaining Highly Purified Toxoplasma gondii Oocysts by a Discontinuous Cesium Chloride Gradient

This study describes the development of a modified CsCl method that easily purifies T. gondii oocysts from feces of infected cats that are suitable for molecular biological and tissue culture manipulation

고도 정화 구하기 Toxoplasma gondii</em불연속 세슘 클로라이드 그라디언트로> Oocysts

Toxoplasma gondii is an obligate intracellular protozoan pathogen that commonly infects humans. It is a well characterized apicomplexan associated with ...

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Toxoplasma gondii Cyst Wall Formation in Activated Bone Marrow-derived Macrophages and Bradyzoite Conditions

Toxoplasma gondii is an obligate intracellular parasite that can invade any nucleated cell of warm-blooded animals. During infection, T. gondii disseminates as a fast replicating form called the tachyzoite. Tachyzoites convert into a slow-growing encysted form called the bradyzoite by a signaling process that is not well characterized. Within animals, bradyzoite cysts are found in the central nervous system and muscle tissue and represent the chronic stage of infection. Conversion to bradyzoites can be simulated in tissue culture by CO2 starvation, using medium with high a pH, or the addition of interferon gamma (IFN&gamma;). Bradyzoites are characterized by the presence of a cyst wall, to which the lectin Dolichos biflorus agglutinin (DBA) binds. Fluorescently labeled DBA is used to visualize the cyst wall in parasites grown in human foreskin fibroblasts (HFFs) that have been exposed to low CO2 and high pH medium. Similarly, parasites residing in murine bone marrow-derived macrophages (BMMs) display a cyst wall detectable by DBA after the BMMs are activated with IFN&gamma; and lipopolysaccharide (LPS). This protocol will demonstrate how to induce conversion of T. gondii to bradyzoites using a high pH growth medium with low CO2 and activation of BMMs. Host cells will be cultured on coverslips, infected with tachyzoites and either activated with addition of IFN&gamma; and LPS (BMMs) or exposed to a high pH growth medium (HFFs) for three days. Upon completion of infections, host cells will be fixed, permeabilized, and blocked. Cyst walls will be visualized using rhodamine DBA with fluorescence microscopy.

Toxoplasma gondii Cyst Wall Formation in Activated Bone Marrow-derived Macrophages and Bradyzoite Conditions

Toxoplasma gondii converts to a cyst form in response to environmental stresses, which can be mimicked in tissue culture models. This video demonstrates techniques to examine cyst wall formation by activating bone marrow-derived macrophages or changing growth medium pH in fibroblast cells.

활성 골수 - 유래 Macrophages과 Bradyzoite Toxoplasma gondii 약관의 낭종의 벽 형성

Toxoplasma gondii is an obligate intracellular parasite that can invade any nucleated cell of warm-blooded animals. During infection, T. gondii ...

Transnuclear Mice with Pre-defined T Cell Receptor Specificities Against Toxoplasma gondii Obtained Via SCNT

Lymphocytes, such as T cells, undergo genetic V(D)J recombination, to generate a receptor with a certain specificity1. Mice transgenic for a rearranged antigen-specific T cell receptor (TCR) have been an indispensable tool to study T cell development and function. However, such TCRs are usually isolated from the relevant T cells after long-term culture often following repeated antigen stimulation, which unavoidably selects for T cells with high affinity. Random genomic integration of the TCR &alpha;- and &beta;-chain and expression from non-endogenous promoters can lead to variations in expression level and kinetics.
Epigenetic reprogramming via somatic cell nuclear transfer provides a tool to generate embryonic stem cells and mice from any cell of interest. Consequently, when SCNT is applied to T cells of known specificity, these genetic V(D)J rearrangements are transferred to the SCNT-embryonic stem cells (ESCs) and the mice derived from them, while epigenetic marks are reset. We have demonstrated that T cells with pre-defined specificities against Toxoplasma gondii can be used to generate mouse models that express the specific TCR from their endogenous loci, without experimentally introduced genetic modification. The relative ease and speed with which such transnuclear models can be obtained holds promise for the construction of other disease models.

Transnuclear Mice with Pre-defined T Cell Receptor Specificities Against Toxoplasma gondii Obtained Via SCNT

We demonstrate here that epigenetic reprogramming via Somatic Cell Nuclear Transfer (SCNT) can be used as a tool to generate mouse models with pre-defined T cell receptor (TCR) specificities. These transnuclear mice express the corresponding TCR from their endogenous locus under the control of the endogenous promoter.

반대 미리 정의된 T 세포 수용체 Specificities와 Transnuclear 쥐 Toxoplasma gondii SCNT 비아 획득

Lymphocytes, such as T cells, undergo genetic V(D)J recombination, to generate a receptor with a certain specificity1. Mice transgenic for a rearranged ...

Selection of Plasmodium falciparum Parasites for Cytoadhesion to Human Brain Endothelial Cells

Most human malaria deaths are caused by blood-stage Plasmodium falciparum parasites. Cerebral malaria, the most life-threatening complication of the disease, is characterised by an accumulation of Plasmodium falciparum infected red blood cells (iRBC) at pigmented trophozoite stage in the microvasculature of the brain2-4. This microvessel obstruction (sequestration) leads to acidosis, hypoxia and harmful inflammatory cytokines (reviewed in 5). Sequestration is also found in most microvascular tissues of the human body2, 3. The mechanism by which iRBC attach to the blood vessel walls is still poorly understood.
The immortalized Human Brain microvascular Endothelial Cell line (HBEC-5i) has been used as an in vitro model of the blood-brain barrier6. However, Plasmodium falciparum iRBC attach only poorly to HBEC-5i in vitro, unlike the dense sequestration that occurs in cerebral malaria cases. We therefore developed a panning assay to select (enrich) various P. falciparum strains for adhesion to HBEC-5i in order to obtain populations of high-binding parasites, more representative of what occurs in vivo.
A sample of a parasite culture (mixture of iRBC and uninfected RBC) at the pigmented trophozoite stage is washed and incubated on a layer of HBEC-5i grown on a Petri dish. After incubation, the dish is gently washed free from uRBC and unbound iRBC. Fresh uRBC are added to the few iRBC attached to HBEC-5i and incubated overnight. As schizont stage parasites burst, merozoites reinvade RBC and these ring stage parasites are harvested the following day. Parasites are cultured until enough material is obtained (typically 2 to 4 weeks) and a new round of selection can be performed. Depending on the P. falciparum strain, 4 to 7 rounds of selection are needed in order to get a population where most parasites bind to HBEC-5i. The binding phenotype is progressively lost after a few weeks, indicating a switch in variant surface antigen gene expression, thus regular selection on HBEC-5i is required to maintain the phenotype.
In summary, we developed a selection assay rendering P. falciparum parasites a more "cerebral malaria adhesive" phenotype. We were able to select 3 out of 4 P. falciparum strains on HBEC-5i. This assay has also successfully been used to select parasites for binding to human dermal and pulmonary endothelial cells. Importantly, this method can be used to select tissue-specific parasite populations in order to identify candidate parasite ligands for binding to brain endothelium. Moreover, this assay can be used to screen for putative anti-sequestration drugs7.

Selection of Plasmodium falciparum Parasites for Cytoadhesion to Human Brain Endothelial Cells

An in vitro model for cerebral malaria sequestration is described1. Plasmodium falciparum infected red blood cells are selected for binding to immortalized human brain microvascular endothelial cells. The selected parasites show a distinct phenotype. The selection process can be applied using various P. falciparum strains and endothelial cell lines.

선정 Plasmodium falciparum</em인간 두뇌 내피 세포 Cytoadhesion위한> 기생충

Most human malaria deaths are caused by blood-stage Plasmodium falciparum parasites. Cerebral malaria, the most life-threatening complication of the ...

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.

분리하기위한 유전자 스크린 Toxoplasma gondii 호스트 세포 재현의 돌연변이

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).

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.

유전 조작<em&gt; Δku80</em의 기능 게놈 분석을위한&gt; 균주<em&gt; 톡소 포자충</em

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

Forward Genetic Approaches in Chlamydia trachomatis

Chlamydia trachomatis, the etiological agent of sexually transmitted diseases and ocular infections, remains poorly characterized due to its intractability to experimental transformation with recombinant DNA. We developed an approach to perform genetic analysis in C. trachomatis&#160;despite the lack of molecular genetic tools. Our method involves: i.) chemical mutagenesis to rapidly generate comprehensive libraries of genetically-defined mutants with distinct phenotypes; ii.) whole-genome sequencing (WGS) to map the underlying genetic lesions and to find associations between mutated gene(s) and a common phenotype; iii.) generation of recombinant strains through co-infection of mammalian cells with mutant and wild type bacteria. Accordingly, we were able to establish causal relationships between genotypes and phenotypes. The coupling of chemically-induced gene variation and WGS to establish correlative genotype&#8211;phenotype associations should be broadly applicable to the large list of medically and environmentally important microorganisms currently intractable to genetic analysis.

Forward Genetic Approaches in Chlamydia trachomatis

We describe a methodology to perform genetic analysis in Chlamydia based on chemical mutagenesis and whole genome sequencing. In addition, a system for DNA exchange within infected cells is described that can be used for genetic mapping. This method may be broadly applicable to microbial systems lacking transformation systems and molecular genetic tools.

앞으로 유전 접근<em&gt; 클라미디아의 trachomatis</em

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

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.

유전자의 식별을위한 VIGS - 중재 앞으로 유전학 검사는 Nonhost 저항에 참여


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

Using RNA-interference to Investigate the Innate Immune Response in Mouse Macrophages

Macrophages are key phagocytic innate immune cells. When macrophages encounter a pathogen, they produce antimicrobial proteins and compounds to kill the pathogen, produce various cytokines and chemokines to recruit and stimulate other immune cells, and present antigens to stimulate the adaptive immune response. Thus, being able to efficiently manipulate macrophages with techniques such as RNA-interference (RNAi) is critical to our ability to investigate this important innate immune cell. However, macrophages can be technically challenging to transfect and can exhibit inefficient RNAi-induced gene knockdown. In this protocol, we describe methods to efficiently transfect two mouse macrophage cell lines (RAW264.7 and J774A.1) with siRNA using the Amaxa Nucleofector 96-well Shuttle System and describe procedures to maximize the effect of siRNA on gene knockdown. Moreover, the described methods are adapted to work in 96-well format, allowing for medium and high-throughput studies. To demonstrate the utility of this approach, we describe experiments that utilize RNAi to inhibit genes that regulate lipopolysaccharide (LPS)-induced cytokine production.

In this protocol, we describe methods to efficiently transfect murine macrophage cell lines with siRNAs using the Amaxa Nucleofector 96-well Shuttle System, stimulate the macrophages with lipopolysaccharide, and monitor the effects on inflammatory cytokine production.

마우스 대 식세포의 타고난 면역 반응을 조사하기 위해 RNA 간섭을 사용하여

Macrophages are key phagocytic innate immune cells.  When macrophages encounter a pathogen, they produce antimicrobial proteins and compounds to kill the ...

Neutrophil Isolation and Analysis to Determine their Role in Lymphoma Cell Sensitivity to Therapeutic Agents

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of inflammation. They are key players in the innate immune system and play major roles in cancer biology. Neutrophils have been proposed as key mediators of malignant transformation, tumor progression, angiogenesis and in the modulation of the antitumor immunity; through their release of soluble factors or their interaction with tumor cells. To characterize the specific functions of neutrophils, a fast and reliable method is coveted for in vitro isolation of neutrophils from human blood. Here, a density gradient separation method is demonstrated to isolate neutrophils as well as mononuclear cells from the blood. The procedure consists of layering the density gradient solution such as Ficoll carefully above the diluted blood obtained from patients diagnosed with chronic lymphocytic leukemia (CLL), followed by centrifugation, isolation of mononuclear layer, separation of neutrophils from RBCsby dextran then lysis of residual erythrocytes. This method has been shown to isolate neutrophils &#8805; 90 % pure. To mimic the tumor microenvironment, 3-dimensional (3D) experiments were performed using basement membrane matrix such as Matrigel. Given the short half-life of neutrophils in vitro, 3D experiments with fresh human neutrophils cannot be performed. For this reason promyelocytic HL60 cells are differentiated along the granulocytic pathway using the differentiation inducers dimethyl sulfoxide (DMSO) and retinoic acid (RA). The aim of our experiments is to study the role of neutrophils on the sensitivity of lymphoma cells to anti-lymphoma agents. However these methods can be generalized to study the interactions of neutrophils or neutrophil-like cells with a large range of cell types in different situations.

Neutrophils are the most abundant type of white blood cells. The isolation of neutrophils from human blood by density gradient separation method and the differentiation of human promyelocytic (HL60) cells along the granulocytic pathway are described here; to test their role on sensitivity of lymphoma cells to anti-lymphoma agents.