Poxviridae by GR Carter and DJ Wise; A3410.1005

Viral Characteristics Large, enveloped (some virions contain double envelope), double-stranded DNA viruses (see Fig. 10.1). The capsid / nucleocapsid is brick-shaped to ovoid containing the genome and lateral bodies (function unknown). The large complex genome consists of a single, linear molecule of double stranded DNA that codes for approximately 200 proteins. The ends are ligated to each other so the DNA molecule is continuous, without free ends. These are the only DNA viruses known to complete their replication cycle in the cytoplasm. In the cytoplasm, the dsDNA is used as a template for both mRNA production (for translation of proteins) and copies of the genome for progeny virions; viral enzymes largely mediate both processes. As the virions are large and complex, the mechanism associated with virion assembly is largely unknown. Virions are released from the cell by budding. Viruses of this family possess at least 10 major antigens with a common nucleoprotein antigen, which accounts for cross-reactivity among species. There are at least 10 viral enzymes contained within the virus particle, many of which function in nucleic acid metabolism and genome replication. Poxviruses remain viable in scabs for long periods. Some (mainly orthopoxviruses) produce hemagglutinins that agglutinate red blood cells. Eosinophilic inclusions called Guarnieri bodies may be produced in infected cells/tissues. Viral Characteristics Classification Orthopoxvirus: Vaccinia Variola Cowpox Feline Cowpox Horsepox Camelpox Buffalopox Monkeypox Parapoxvirus: Bovine Papular Stomatitis Contagious Ecthyma Pseudocowpox Capripoxvirus: Sheeppox, Goatpox Lumpy Skin Disease Avipoxvirus: Fowlpox Canarypox Leporipoxvirus: Myxomatosis Suipoxvirus: Swinepox Glossary