蚊媒刺叮对Balb/C小鼠感染登革Ⅱ型病毒的增强作用

MOSQUITO FEEDING-INDUCED ENHANCEMENT OF DENGUE VIRUS INFECTION IN MICE

登革热 登革出血热是我国重要的蚊媒病之一 ,白纹伊蚊和埃及伊蚊是主要媒介蚊种。本研究以Balb C小鼠为实验动物 ,探讨白纹伊蚊唾液对登革病毒感染宿主的增强作用。结果显示 ,在感染剂量相同的情况下 ,如果Balb C实验小鼠预先被一定数量的白纹伊蚊叮咬以后再皮下接种病毒 ,实验小鼠感染登革病毒的程度有所提高媒介蚊虫叮咬宿主吸血时会分泌唾液,蚊媒病毒随分泌的唾液传播给宿主,蚊虫唾液不仅是病毒传播的液体环境,还对病毒感染宿主有一定促进作用,通过影响宿主的免疫功能而起作用。蚊虫等吸血双翅目昆虫由于吸血时间短,被叮咬的宿主免疫系统可能来不及发生反应,所以以前推测它们对宿主免疫方面的作用可能比较小或没有(Champagne,1994)。近年研究发现能抑制或调节动物宿主免疫反应,影响宿主对虫媒病原体的免疫能力,如发现白蛉唾液中的舒血管物质能抑制宿主巨噬细胞功能,增加利什曼原虫的感染(TitusandRibeiro,1988;Theodosetal.,1993),之后相关的研究逐渐多起来(Bissonnetteetal.,1993;Crossetal.,1994)。对Cachevalley病毒感染传播研究发现只有通过蚊虫有效的叮咬Balbc实验小鼠才能产生病毒血症和相应的抗体,而仅皮下注射病毒则不能(Edwardsetal.,1998);

Dengue fever (DF)/Dengue haemorrhagic fever (DHF) is one of the most important human arbo virus infectious diseases in tropical and subtropical areas with increasing number of patients and the expansion of epidemic areas.Understanding the mechanisms of its infection and spreading is the foundation for dengue and its vector mosquito surveillence and control.The siliva secreted with mosquito feeding is not only the liquid vector of virus spreading,but also can enhance virus infection through immuno modulation to its vertebrate host.It had been found in the infections of La Cross virus and Cache Valley virus,that mosquito feeding induced enhancement of mosquito borne virus infection.Whether vector mosquito can enhance infection of dengue virus is also an important problem needing to be studied,which will also help to understand the pathologic mechanisms of dengue virus with antibody dependent enhancement.Related studies have not been reported. Based on Den 2 virus infection on Balb/C laboratory mice,it was studied to whether it was enhanced by vector mosquito Aedes albopictus. After biting by a number of mosquitoes,the laboratory mice were injected intravenously with a defined titers of Den 2 virus.The differences in viremia,the titers of Den 2 antibodies,the infection rates of macrophages in abdominal cavity were observed compared with those just injected Den 2 virus.Then Following are the results.After biting by a number of vector mosquitoes Ae.albopictus, the mice become easier to be infected with Den 2 virus,with its periods of viremia elongated from 1～2 days to 4days,the titers of antibody dropped from 1∶64,1∶96 to 1∶16,1∶32 respectively in the 4 th ,7 th days after injected,a varied infection rates of macrophages in the first 7 days.These results indicated vector mosquito feeding could enhance mice infection with Den 2 virus.