本文選題：西方馬腦炎病毒 + 淡色庫蚊��； 參考：《中國人民解放軍軍事醫(yī)學科學院》2007年博士論文

【摘要】： 西方馬腦炎病毒(western equine encephalomyelitis virus，WEEV)屬于披膜病毒科(Togaviridae)甲病毒屬(Alphaviruses)。它能夠引起人類和馬等動物的致死性疾病——腦炎，對馬的病死率可達50％，對人的病死率最高可達10％，嬰幼兒患者常會導致智力低下、行為失常等。目前已知該病主要分布于加拿大、美國西部和中部、墨西哥、圭亞那、巴西、阿根廷、秘魯、智利和烏拉圭等國家。該病在北美地區(qū)呈地方性流行，以不規(guī)則的間隔在馬和人群中引起流行。環(huán)跗庫蚊(Culex tarsalis)已被證明是北美地區(qū)西方馬腦炎病毒的主要傳播媒介，同時血清學調查證明了鳥類在病毒循環(huán)中的作用。在自然界中，病毒只在野鳥—蚊之間進行傳播，主要是在環(huán)跗庫蚊與野鳥之間；人和馬是其非固有的感染對象，稱為“終末宿主”。此外，經證實能夠自然或實驗室感染WEEV的還有其它庫蚊屬(Culex)、按蚊屬(Anopheles)、伊蚊屬(Aedes)等7個屬20多種蚊蟲，也有從虱、蜱、螨等節(jié)肢動物體內分離病毒的報道。雖然西方馬腦炎只在美洲大陸上發(fā)生，但其仍然是國際嚴密監(jiān)控的人畜共患傳染病。除了美洲以外，波蘭和前蘇聯也曾報道從正常人血中測得西方馬腦炎抗體，1962年首次從俄羅斯分離出西方馬腦炎病毒株Y62-33。我國1990年分別從新疆烏蘇縣的一組赫坎按蚊(Anopheles hyrcanus)和博樂縣的全溝硬蜱(Ixodes persulcatus)中分離出WEEV，這是在歐亞大陸除俄羅斯外發(fā)現的第二例WEEV分離的報道。在對我國人體血清學調查中發(fā)現，WEEV抗體陽性率為2.71％。這些情況都表明了WEEV在我國的存在。近年來我國每年均有大量不明原因發(fā)熱及腦炎病例的報道，提示WEEV可能是我國感染性疾病的新病原之一。此外，WEEV被列為二類生物恐怖試劑，如果WEEV經氣溶膠方式撒布后，當地的宿主動物如鳥類等被感染，那么易感蚊蟲就有可能通過吸血將西方馬腦炎傳播給人類，造成更大范圍的傳染病暴發(fā)。因此針對WEEV對我國潛在的威脅，我們首先需要明確在我國的一些優(yōu)勢種蚊蟲能否感染和傳播WEEV，了解它們對WEEV的傳播能力，結合生態(tài)習性確定哪些是主要的潛在媒介，以便制訂應對一旦西方馬腦炎暴發(fā)后的相應的防治策略。 在我國，淡色庫蚊(Cx.p.pallens)和致倦庫蚊(Cx.p.quinquefasciatus)是尖音庫蚊復合組(Cx.pipiens Complex)成員，嗜吸人血，兼吸禽血，是我國城鎮(zhèn)的優(yōu)勢蚊種；白紋伊蚊(Ae.albopictus)和埃及伊蚊(Ae.aegypti)是登革熱的主要傳播媒介，也是我國的重要蚊種；三帶喙庫蚊(Cx.tritaeniorhynchus)廣泛地分布于我國水稻種植區(qū)，嗜吸畜血，兼吸人、雞血等。本研究以這幾種在我國十分重要的蚊種為對象，在實驗室條件下，通過蚊蟲叮咬人工感染WEEV的來亨雞，采用免疫熒光檢測病毒抗原和RT-PCR檢測病毒核酸等方法檢測蚊蟲體內病毒，確定受試蚊蟲對WEEV的易感性和傳播能力；探討蚊蟲對WEEV的易感機制，為進一步深入理解病毒與媒介的相互作用，尋求對病媒蚊蟲的有效防控手段提供科學依據。本工作主要結果如下： 1．我國重要蚊種對WEEV的經口感染率 在實驗室條件下，叮咬人工感染WEEV的來亨雞后，淡色庫蚊、致倦庫蚊、三帶喙庫蚊、白紋伊蚊和埃及伊蚊對WEEV均易感，其感染率分別為45.5％、60.0％、80.0％、36.7％和25.0％，不同蚊種之間的感染率有顯著性差異(x~2=13.709，P=0.008)，其中三帶喙庫蚊感染率最高，為80.0％。 2．我國重要蚊種對WEEV的刺叮傳播率 在實驗室條件下，淡色庫蚊、致倦庫蚊、白紋伊蚊和埃及伊蚊都能通過刺叮吸血將體內的WEEV傳播給易感動物1～3日齡的來亨雞，傳播率分別為40.74％、53.13％、57.14％和45.16％，不同蚊種之間的傳播率沒有顯著性差異(x~2=1.879，P=0.598)。 3．WEEV在蚊蟲體內的散布率 在實驗室條件下，WEEV在已感染的淡色庫蚊、致倦庫蚊、三帶喙庫蚊、白紋伊蚊和埃及伊蚊體內均能擴散至足，散布率分別為60.0％、61.1％、75.0％、54.5％和50.0％。不同蚊種間的散布率沒有顯著性差異(x~2=1.229，P=0.873)。 4．WEEV在感染蚊蟲體內擴散與蚊蟲經口傳播病毒的相關性研究 本研究通過對感染和傳播實驗中的單只蚊蟲進行標記，根據它們感染、擴散和傳播的結果進行統計分析發(fā)現，感染病毒并擴散至足的絕大多數蚊蟲能夠將病毒傳播給易感動物、也有極少數不能經口傳播；一些感染病毒但未擴散至足的蚊蟲也是一部分能夠經口傳播而另一部分不能；還存在一些體內檢測不出病毒，，其叮咬的來亨雞卻能被感染。 5．西方馬腦炎病毒抗原在經口感染淡色庫蚊體內的分布 淡色庫蚊在經口感染WEEV 3～4天后，部分蚊蟲中腸壁見有WEEV的侵染。個別蚊蟲后腸出現陽性斑塊；第7～10d，部分蚊蟲中腸、馬氏管、卵巢、后腸均見病毒侵染；第10～14d，除中腸和卵巢等呈陽性反應外；可見唾液腺亦被病毒侵染；但有些蚊蟲個體僅在中腸有陽性反應，其它組織器官均為陰性；還有部分蚊蟲個體組織器官均未見陽性反應。因此認為，淡色庫蚊對WEEV的易感性存在個體差異，不易感的個體體內可能存在中腸屏障，而傳播能力的差異可能是由于唾液腺屏障的存在。
[Abstract]:The western equine encephalitis virus ( WEEV ) belongs to the genus Togaviridae . It can cause fatal disease _ encephalitis in humans and horses . The mortality rate of horses is up to 10 % . The disease is endemic in North America . The disease is endemic in the West and Central America , Mexico , Guyana , Brazil , Argentina , Peru , Chile and Uruguay .
In the past few years , China has reported that WEEV may be one of the new pathogens of infectious diseases in China . In recent years , China has reported that WEEV is one of the new pathogens of infectious diseases in China . In recent years , China has reported that WEEV is a new pathogen of infectious diseases in China .









In our country , Cx . p . quinquefasciatus and Cx . p . quinquefasciatus were the members of Cx . pileus complex .
aegypti and aegypti are the main media of dengue fever , and it is also an important mosquito species in China ;
In order to determine the susceptibility and transmission ability of the infected mosquitoes to WEEV in the laboratory , the infected chickens infected with WEEV were detected by immunofluorescence assay and RT - PCR , and the susceptibility and transmission ability of the infected mosquitoes to WEEV were determined .
To explore the susceptibility mechanism of mosquitoes to WEEV , to further understand the interaction between virus and medium , to provide scientific basis for effective prevention and control of vector mosquitoes . The main results of this work are as follows :









1 . Infection rate of China ' s important mosquito species to WEEV









The infection rate was 44.5 % , 60.0 % , 80.0 % , 33.7 % and 25.0 % , respectively , and the infection rate among different species was significantly different ( x ~ 2 = 13.709 , P = 0.008 ) . Among them , the infection rate among the three species was the highest , which was 80.0 % .









2 . sting propagation rate of important mosquito species in China to WEEV









The WEEV in the body could be transmitted to the 1 - 3 day - old hen in the laboratory . The rate of transmission was 40.74 % , 53.13 % , 57.14 % and 45.16 % , respectively , and there was no significant difference between the different species ( x ~ 2 = 1.879 , P = 0.598 ) .









3 . Distribution rate of WEEV in mosquitoes









In laboratory conditions , WEEV was able to diffuse to the foot in the infected light - colored culex , quinquefasciatus , tritaeniorpius , aegypti , aegypti and aegypti , with the spreading rate of 60.0 % , 61.1 % , 75.0 % , 54.5 % and 50.0 % , respectively . There was no significant difference among the spreading rates among different species ( x ~ 2 = 1.229 , P = 0.873 ) .









Study on the relationship between the diffusion of WEEV and the spread of mosquitoes in infected mosquitoes









Based on the results of infection , diffusion and transmission , the study found that the majority of mosquitoes infected with the virus and spread to the foot were able to spread the virus to the susceptible animals , and that a small number of mosquitoes could not be transmitted through the mouth .
Some mosquitoes that are infected with the virus but not enough to spread to the foot are also part of the virus that can travel through the mouth and the other part cannot ;
There are also some in - vivo detection of the virus , but the bite of the hen can be infected .









5 . Distribution of the Western equine encephalitis virus antigen in the body of the infected pale - color culex piquefasciatus









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