Classification of Viruses @ Classification is by two ways: 1. By structure of nucleic acid 2. By size, envelope, capsid shape Tobacco mosaic virus : 1.

Classification of Viruses

@ Classification is by two ways: 1. By structure of nucleic acid

2. By size, envelope, capsid shape

Tobacco mosaic virus : 1st discovered in history

DNA VIRUSES

1. 3 non-enveloped families:

* Papovaviruses, * Adenoviruses

* Parvoviruses,

2. 3 enveloped families :

a) Hepadnaviruses

b) Herpesviruses c) Poxviruses

DNA strand

Papovaviruses

@ Double-stranded circular DNA.

e.g. Human papilloma-virus

Adenoviruses

@ Have Double-stranded linear DNA

@ Contain 40 antigenic types .

Parvoviruses

@ Very small, Single stranded

linear DNA.

@ 2 types of parvoviruses:

* Defective

• * Non-defective

Hepadnaviruses

@ Double-stranded

e.g Hepatitis B virus

Herpesviruses

@ Double stranded, linear DNA

e.g Herpes simplex virus

Poxviruses

@ Largest virus with a bricklike shape

e.g. Smallpox virus

RNA VIRUSES

@ 14 families: Picornavirus Calicivirus

Reovirus Flavivirus Togavirus

Retrovirus Orthomyxovirus

RNA Structure

Paramyxovirus

Rhabdovirus

Filovirus

Coronavirus

Arenavirus

Bunyavirus

Deltavirus . Double stranded RNA

Picornaviruses

@ Smallest virus in size

@ Single stranded, linear RNA within a

non-enveloped icosahedral capsid.

e.g, Poliovirus

Caliciviruses

@ Non-enveloped, icosahedral capsid.

@ Single stranded, linear, RNA.

e.g. Hepatitis E virus.

3D Calicivirus

Reoviruses

@ Non-enveloped family with two icosahedral capsid coats.

@ Double stranded , linear RNA.

e.g. Rotavirus.

Flaviviruses

@ Enveloped, icosahedral, Single stranded, linear, RNA viruses e.g. Yellow fever virus,

Togaviruses

@ Enveloped, icosahedral, Single stranded, linear, RNA family

e.g. Rubella virus

Retroviruses

@ Enveloped, icosahedral, with Single stranded linear RNA family

e.g. HIV .

Orthomyxoviruses

@ Enveloped, helical capsid and linear, Single stranded RNA.

e.g. Influenza virus

Paramyxoviruses

@ Enveloped, helical, Single stranded, linear, RNA family

e.g. Measles virus

Rhabdoviruses

@ Bullet-shaped, enveloped, with a helical, Single stranded, linear, RNA family.

e.g. Rabies virus

Filoviruses

@ Enveloped, helical, Single stranded , linear, RNA family.

e.g. Ebola virus .

Coronaviruses

@ Enveloped, helical, Single stranded , linear, RNA family.

@ "corona" refers to crown of spikes protruding from envelope.

Arenaviruses

@ Enveloped, helical, Single stranded, circular RNA family

e.g. Lassa fever virus.

Bunyaviruses

@ Enveloped, helical, Single stranded, circular, RNA family.

@ "bunya" refers to the place in Africa where it was isolated.

Deltavirus

@ Enveloped, helical, circular, Single stranded RNA family

e.g. Hepatitis delta virus (HDV)