Viruses Associated with Respiratory Infections Chapter 20 Viruses Associated with Respiratory Infections 呼吸道感染病毒

Categories of respiratory viruses Myxovirus •orthomyxovirus •paramyxoviruses SARS coronavirus(SARS Cov) Other respiratory viruses (influenza virus) (measles virus,so.on.)

Influenza Virus 流行性感冒病毒 • orthomyxovirus(正粘病毒) • pathogen of influenza

Outline Biological Properties Pathogenicity and Immunity Laboratory Diagnosis Prophylaxis and Treatment

Ⅰ.Biological Properties 1.Shape and structure  Shape d=80-120 nm,spherical  Structure segmented ㈠ssRNA Nucleoprotein(NP) RNA-dependent RNA polymerase (易发生基因重组) Viral core (具型特异性, Ag性稳定) (nucleocapsid) Viral envelope • matrix protein (M1) • lipid bilayer (具型特异性, Ag性稳定) HA and NA •病毒的表面抗原 •具亚型特异性 •Ag性不稳而易变 membrane protein(M2) spikes

Structure of influenza virus segmented ssRNA M1 (negative sense, 8 or 7 segments) M2 Viral envelope 1 2 3 4 5 6 7 8 matrix protein viral core RNA-dependent RNA polymerase PB2 lipid bilayer PB1 PA HA RNA NA NP RNPi.e. nucleocapsid

helical nucleocapsid structure of virion Viral envelope Viral core ---- helical nucleocapsid structure of virion (RNA+ NP = RNP) Viral envelope (MP+lipid bilayer+spike)

Spikes • glycoprotein • surface antigen of virus • 2 types: HA and NA * subtype-specific * labile and variable in antigenicity HA1, HA2 function * Hemagglutinin (HA) * Neuraminidase (NA) 凝集红细胞 吸附宿主细胞具有抗原性 function 参与病毒释放 促进病毒扩散 具有抗原性

2.Typing and Variation Typing • type: A,B,C • subtypes:H1~H15 and N1~N9 Labile and much variable in antigenicity of HA and NA  Form of variation • antigenic drift → median or small epidemic of influenza • antigenic shift → pandemic of influenza (point mutation→variant) (reassortment→form new subtype)

3.Cultivation Embryonated eggs inoculation Tissue culture

Ⅱ.Pathogenicity & Immunity route of transmission influenza and complication 2.Immunity anti-HA (SIgA important) specific CMI (CD4+T/CD8+T cell) subtype-specific immunity

Ⅲ.Laboratory Diagnosis 1.Isolation of viruses 2.Detection of antibody (hemagglutination inhibition test) 3.Quick diagnosis (Immunolabelling technique,PCR)

Hemagglutination inhibition test a.virus+RBC→agglutination of RBC HA receptoe (hemagglutination) b.(virus+serum)+RBC  早,晚期血清 absence of agglutination (hemagglutination inhibition)

Ⅳ.Principle of Prophylaxis and Therapy

Paramyxovirus (副粘病毒) Inclusion: measles virus, mumps virus, parainfluenza virus and respiratory syncytial virus (RSV) Differ from orthomyxoviruses larger diameter different spikes (HN, H, G and F protein) nonsegmented ss-RNA obvious CPE d=150-300nm (融合细胞与包涵体)

1.Biological properties Measles Virus 麻疹病毒 1.Biological properties (spherical,enveloped virus) Spikes: HA and HL (haemolysin)  Nonsegmented ss-RNA (negative sense)  Single serotype  Typical CPE in cell culture HA---凝集猴红细胞,与受体结合; HL---溶血和融合作用

2.Pathogenicity and immunity • feature of infection • pathogen of measles • complication (viral receptor----CD46 ) (pneumonnia, encephalitis and SSPE)  Immunity (lifelong immunity)

 Laboratory diagnosis  Specific provention •Artificial active immunity (live attenuated vaccine or MMR) •Artificial passive immunity

Mumps & complications lifelong immunity Artificial active immunity Mumps Virus 腮腺炎病毒 (pathogen of mumps) Single serotype Mumps & complications lifelong immunity Artificial active immunity (live attenuated vaccine , MMR)

Parainfluenza Viruses 副流感病毒 5 types Causes of croup (type 1,2) Also cause pneumonia in children and common cold in adults 哮吼---急性喉气管支气管炎

Respiratory Syncytial Virus (RSV) 呼吸道合胞病毒 Spike: G and F protein Pathogenicity •cause bronchiolitis, pneumonia in infants • cause common cold in adults and young children • important pathogen of hospital infection

SARS coronavirus SARS 冠状病毒 (SARS Cov) SARS 冠状病毒 ---pathogen of severe acute respiratory syndrome(SARS) 1.Shape and structure 2.Pathogenicity and immunity d=60~220nm, +ss-RNA，enveloped virus and spike • source of infection • route of transmission • cause SARS • immunity patient 近距离飞沫传播为主 有家庭和医院明显聚集现象 3.Diognosis and prophylaxis

Other Respiratory Viruses 1.Adenovirus  naked virus with ds-DNA and cubic nucleocapsid  typical CPE and pathogenicity (p207表:呼吸道感染、眼部感染、腹泻等) 2.Rubella virus  single antigen type  cause rubella and congenital rubella syndrome (MMR) 3.Rhinovirus ＞114 type The most important pathogen of common cold