Chapter 23

 Arbovirus of prevalence in China ---classified as Flavivirus ---classified as Flavivirus  Small spherical particle(40-70nm), +ssRNA, icosahedral nucleocapsid, envelope and spike  Feature of diseases caused by Arbovirus 主要有流行性乙型脑炎病毒、登革病毒和森林脑炎病毒 一群节肢动物媒介病毒 p302 表 arthropod----both vector and reservoir hosts of virus transmitted by bite of arthropod obvious season and district clinical manifestations ( 发热、脑炎、出血热 )arthropod----both vector and reservoir hosts of virustransmitted by bite of arthropodobvious season and districtclinical manifestations ( 发热、脑炎、出血热 ) 节肢动物既是传播 媒介又是储存宿主  Common characteristics

(JEV) also called Japanese encephalitis virus(JEV) the most common cause of epidemic encephalitis

1. Biological Properties Cultivation  Cultivation Antigenicity  Antigenicity Typical flavivirus both in  Typical flavivirus both in structure and in shape structure and in shape Structural protein:C,M and E protein  Structural protein:C,M and E protein (hemagglutinin) 能凝集雏鸡、鸽和鹅的红细胞（ PH6.0) +ss-RNA suckling mice embryo-eggs cell culture(C6/36 cell) suckling mice embryo-eggs cell culture(C6/36 cell) (single and stable) ( 球形、单正链 RNA 、 20 面体对称的包膜病毒 ) ( 球形、单正链 RNA 、 20 面体对称的包膜病毒 )

 Natural cycles of JEV mosquitodomestic animal mosquito domestic animal or birds or birds domestic animal mosquito or birds or birds (viremia) 病毒血症 病毒血症 bite human (culex) (young pigs) ova vector of transmission and reservoir source of infection route of transmission bite epidemic season and district 蠛蠓, 蝙蝠 蚊 → 动物 → 蚊 --- 三节吻库蚊 --- 幼猪 2.Pathogenicity and Immunity

 JEV-infection Asymptomatic infection Asymptomatic infection Abortive infection Abortive infection Cause epidemic encephalitis B (0.1%) Cause epidemic encephalitis B (0.1%) (neurotropic virus→infection of CNS)  Immunity ---long-lasting immunity (IgM→IgG)

3.Laboratory Diagnosis  Isolation of virus  Serological diagnosis  Isolation of virus (cell culture)  Serological diagnosis 急性期阳性率 >90% (ACELISA) ---detection of specific IgM by antibody cupture-ELISA (ACELISA) 4. Prevention  Cut off the route of transmission  Artificial active immunity  Vaccination of the young pigs (vector control) (inoculate l ive or killed vaccines)

(pathogen of dengue fever)

1.Biological properties  Shape and structure  Shape and structure (similar to JEV)  Cultivation  4 serotypes  4 serotypes ( 各型间有交叉 ) (C6/36 细胞培养, 乳鼠接种 ) 2. Pathogenicity   Natural cycle of virus human(monkey)→mosquitoes→Human (monkey) vector---- aedes source of infection and reservoir of virus 白纹伊蚊 ( 西太平洋区, 广东 ) 埃及伊蚊 ( 东南亚, 海南 ) 患者和隐感者 ( 人和猴子 ) 5~10 月 3~10 月

 Dengue virus -infection route of transmisson route of transmisson primary infection→dengue fever primary infection→dengue fever reinfection→dengue hemorrhagic fever(DHF) or dengue shock syndrome (DSS) reinfection→dengue hemorrhagic fever(DHF) or dengue shock syndrome (DSS) pathogenesis of DHF/DSS:ADE(antibody- dependent enhancement) pathogenesis of DHF/DSS:ADE(antibody- dependent enhancement) 3.Laboratory diagnosis  Detection of specific IgM (ELISA)  Isolation of virus  Detection of viral RNA

--- 森林脑炎病毒 ( 又称苏联春夏型脑炎病毒 ) ， 是森林脑炎的病原体, 该病是蜱传播的自然疫 源性疾病 ( 也是人畜共患病 ) Forest encephalitis virus ( 森林脑炎病毒 ) 自习

 i mportant pathogens of causing hemorrhagic fever  i mportant pathogens of causing hemorrhagic fever (p306 Table 23-2)  Hemorrhagic feverof prevalence in China  Hemorrhagic fever of prevalence in China 1.hantavirus 2.Xin-jiang hemorrhagic fever virus 3.dengue virus

G1 G2 round or elliptic virus envelope with HA --- segmented -ssRNA (L,M and S) polymerase G1,G2 N d=120 nm 1. Biological properties Ⅰ. Hantavirus 凝集鹅红细胞 PH6.0~6.4  Shape and structure  Genome  Cultivation (Cell culture and susceptible animal)  Epidemic serotype in China Hantaan virus ( 汉滩病毒, 姬鼠型 ) Seoul virus ( 汉城病毒, 褐家鼠型 )

2.Pathogenicity and Immunity  Epidemiology source of infection source of infection mode of transmission mode of transmission mite mite obvious season and district obvious season and district  Clinical syndromes hemorrhagic fever with renal syndrome hemorrhagic fever with renal syndrome (HFRS, 肾综合征出血热 ) (HFRS, 肾综合征出血热 ) Hantavirus pulmonary syndrome (HPS, 汉坦病毒肺综合征） ( 螨, both vectors and reservoir) 带毒的宿主鼠 ( 尿 / 粪 / 唾液 ) ( 尿 / 粪 / 唾液 ) 黑线姬鼠褐家鼠大白鼠 ( 多种途径 ) 秋冬季 春夏季 流行性出血热 (EHF)  Immunity (long-lasting immunity)

3.Laboratory diagnosis and prophylaxis  Laboratory diagnosis ---isolation of virus, detection of viral Ag and specific IgM or of viral RNA  Prophylaxis

2.Pathogenicity   Source of infection   Route of transmission   Cause XinJiang Hemorrhagic Fever 自然疫源性疾病 (by bite of hard tick with viruses) 1.Properties of XHFV (similar to hantavirus) 家畜和野生动物 Ⅱ.XinJiang Hemorrhagic Fever virus 3.Immunity 3. Immunity ---long-lasting immunity