| avian influenza virus | <virology> A type A influenza virus (genus Influenzavirus) that causes fowl plague. Synonym: fowl plague virus. (05 Mar 2000) |
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| influenza a virus, avian | Strains of influenza a virus causing influenza in birds. Transmission is caused by close contact or is waterborne in aquatic species. (12 Dec 1998) |
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| avian influenza | Infection of domestic and wild fowl and other birds with influenza a virus, avian. (12 Dec 1998) |
| haemagglutinin glycoproteins, influenza virus | Membrane glycoproteins from influenza viruses which are involved in haemagglutination, virus attachment, and envelope fusion. Fourteen distinct subtypes of ha glycoproteins and nine of na glycoproteins have been identified from influenza a virus; no subtypes have been identified for influenza b or influenza c viruses. (12 Dec 1998) |
| duck influenza virus | An influenza A virus, a member of the family Orthomyxoviridae, distinct from human influenza A strains on bases of haemagglutination-inhibition. (05 Mar 2000) |
| influenza a virus | The type species of the genus influenzavirus a, b that causes influenza and other diseases in humans and animals. Antigenic variation occurs frequently between strains, allowing classification into subtypes and variants. Transmission is by aerosol (human and most non-aquatic hosts) or waterborne (ducks). (12 Dec 1998) |
| influenza a virus, human | Strains of influenza a virus causing influenza and sometimes pneumonia in humans. Transmission is by aerosol. (12 Dec 1998) |
| influenza a virus, porcine | Strains of influenza a virus causing influenza and pneumonia in domestic pigs. (12 Dec 1998) |
| influenza b virus | Species of the genus influenzavirus a, b that cause influenza and other diseases in humans only. Antigenic variation is less extensive than in type a viruses (influenza a virus) and consequently there is no basis for distinct subtypes or variants. Epidemics are less likely than with type a and there have been no pandemics. (12 Dec 1998) |
| influenza virus | <organism, virology> Member of the Orthomyxoviridae that causes influenza in humans. There are three types of influenza virus. Each type of virus has a stable nucleoprotein group antigen common to all strains of the type, but distinct from that of the other type; each also has a mosaic of surface antigens (haemagglutinin and neuraminidase) which characterise the strains and which are subject to variations of two kinds: 1) a rather continual drift that occurs independently within the haemagglutinin and neuraminidase antigens; 2) after a period of years, a sudden shift (notably in type A virus of human origin) to a different haemagglutinin or neuraminidase antigen. The sudden major shifts are the basis of subdivisions of type A virus of human origin. Type A causes the world wide epidemics (pandemics) of influenza and can infect other mammals and birds. Type B only affects humans. Type C causes only a mild infection. Types A and B virus evolve continuously, resulting in changes in the antigenicity of their spike proteins, preventing the development of prolonged immunity to infection. The spike proteins, external haemagglutinin and neuraminidase have been studied as models of membrane glycoproteins. Strain notations indicate type, geographic origin, year of isolation, and, in the case of type A strains, the characterizing subtypes of haemagglutinin and neuraminidase antigens (e.g., A/Hong Kong/1/68 (H3 N2); B/Hong Kong/5/72). (08 Mar 2000) |
| influenza virus vaccines | Influenza virus grown in embryonated eggs and inactivated, usually by the addition of formalin; both whole virus and subunit preparations containing haemagglutinins and neuraminidase are used; because of the marked and progressive antigenic variation of the influenza viruses, the strains included are regularly changed following various outbreaks of influenza in order to include most recently isolated epidemic strains of both type A influenza and type B influenza. (05 Mar 2000) |
| avian encephalomyelitis virus | <virology> A virus of the genus Enterovirus (family Picornaviridae) causing avian infectious encephalomyelitis in young chicks. (05 Mar 2000) |
| avian erythroblastosis virus | <virology> Group of C type RNA tumour viruses (Oncovirinae) that cause various leukaemias and other tumours in birds. The acute leukaemia viruses, that are replication defective and require helper viruses, include avian erythroblastosis (AEV), myeloblastosis (AMV) and myelo cytomatosis viruses. AEV carries two transforming genes, v erbA and v erbB, the cellular homologue of the latter is the structural gene for the epidermal growth factor receptor. AMV carries v myb and causes a myeloid leukaemia, avian myelocytomatosis virus carries v myc. The avian lymphatic leukaemia viruses (ALV) are also Retroviridae but are replication competent and induce neoplasia only after several months, they often occur in conjunction with replication defective leukaemia viruses. (02 Jan 1998) |
| avian infectious laryngotracheitis virus | <virology> A herpesvirus causing avian infectious laryngotracheitis. (05 Mar 2000) |
| avian leukaemia virus | <virology> Group of C type RNA tumour viruses (Oncovirinae) that cause various leukaemias and other tumours in birds. The acute leukaemia viruses, that are replication defective and require helper viruses, include avian erythroblastosis (AEV), myeloblastosis (AMV) and myelo cytomatosis viruses. AEV carries two transforming genes, v erbA and v erbB, the cellular homologue of the latter is the structural gene for the epidermal growth factor receptor. AMV carries v myb and causes a myeloid leukaemia, avian myelocytomatosis virus carries v myc. The avian lymphatic leukaemia viruses (ALV) are also Retroviridae but are replication competent and induce neoplasia only after several months, they often occur in conjunction with replication defective leukaemia viruses. (02 Jan 1998) |
| avian leukosis-sarcoma virus | avian leukosis-sarcoma complex |