CLASSIFICATION OF VIRUS
Viruses classified based on various factors viz., Host, disease in human, target tissues, mode of transmission, vector, Structure and Nucleic acids. • Viral genome’s nucleic acid (DNA or RNA), strandedness (single-stranded or double-stranded), Sense, and method of replication determine its class. • Other classifications are determined by the disease caused by the virus or its morphology. • Viruses can be placed in one of the seven groups. Classification Based on Structure of Virus • Structurally Virus are 1. Helical Symmetry: ▶ The protein and nucleic acid are arranged in a spiral. ▶ Examples: Tobacco Mosaic Virus (TMV), Rabies, Influenza. ▶ Most helical viruses are enveloped and RNA viruses. 2. Icosahedral Symmetry: ▶ The protein subunits form a symmetrical shell around the nucleic acid core. ▶ An icosahedron has 12 vertices, 20 faces, and 30 edges. ▶ Examples: Poliovirus, Adenovirus, Hepatitis virus. ▶ Icosahedral capsids are stable...
