Classification of Viruses

Types of virus Genomes

Forms of DNA from DNA viruses

Peplomer

Cross section of enveloped virus

Intact enveloped virus

Enveloped helical nucleocapsid

Virus Classification

It is based on following points;

• Nucleic acid type
• Size and morphology
• Susceptibilty to chemical and physical agents
• Viral enzymes
• Immunological properties
• Mode of replication
• Mode of transmission, cell tropisms, pathogenesis and symptomatology

DNA Viruses

• Parvoviridae
• Papovaviridae

1. Papillomavirinae
2. Polyomavirinae

• Adenoviridae
• Herpesviridae
• Poxviridae
• Hepadnaviridae

RNA Viruses

• Picornaviridae
• Caliciviridae
• Reoviridae
• Togaviridae
• Flaviviridae
• Arenaviridae
• Coronaviridae
• Retroviridae
• Bunyaviridae
• Orthomyxoviridae
• Paramyxoviridae
• Rhabdoviridae

Bacteriophage

Bacteriophages are viruses that infect bacteria

Lytic Phage

Phage enter cell, multiply and lyse cell

Example:  T phage of E. coli

Lysogenic Phage

bacteriophage integrate their nucleic acid into genome of the infected host cell (prophage)

Integration of a virus into a cellular genome is termed lysogeny

Example:  lambda phage of E. coli