Classification of virus

September 17, 2017 Gaurab Karki Microbiology, Virology 0




Classification of virus

A] Classification on the basis of nucleic acid

B] Classification on the basis of structure or symmetry

C] Classification on the basis of replication properties and site of replication

D] Classification on the basis of host range

E] Classification on the basis of mode of transmission

Classification of virus on the basis of nucleic acid

 

1. DNA virus:

  • viral genome is DNA

i) Double stranded DNA virus: eg. Adenovirus, Herpesvirus

ii) Single stranded DNA virus: eg. Parvovirus, φ174 virus

2. RNA virus:

  • genome is RNA

i) Double stranded RNA virus: eg. Reo virus

ii) Single stranded RNA virus: these are further classified into two groups

  • Positive sense RNA (+RNA): Polio virus, Hepatitis A
  • Negative sense RNA (-RNA): Rabies virus, Influenza virus

Some examples of DNA and RNA viruses:

Classification of virus on the basis of structure

1. Cubical virus:

  • they are also known as icosahedral symmetry virus
  • Eg. Reo virus, Picorna virus

2. Spiral virus:

  • they are also known as helical symmetry virus
  • Eg. Paramyxovirus, orthomyxovirus

3. Radial symmetry virus:

  • eg.Bacteriophage

4. Complex virus:

  • eg. Pox virus

 

Classification of virus on the basis of replication properties and site of replication

1. Replication and assembly in cytoplasm of host:

  • Eg. All RNA virus replicate and assemble in cytoplasm of host cell except Influenza virus

2. Replication in nucleus and assembly in cytoplasm of host:

  • Eg. Influenza virus, Pox virus

3. Replication and assembly in nucleus of host:

  • All DNA viruses replicate and assemble in nucleus of host cell except Pox virus.

4. Virus replication through ds DNA intermediate:

  • Eg. All DNA virus, Retro virus and some tumor causing RNA virus replicates through ds DNA as intermediates.

5. Virus replication through ss RNA intermediate:

  • Eg. All RNA virus except Reo virus and tumor causing RNA viruses.

 

Classification of virus on the basis of host range:

1. Bacteriophage:

  • Phage are virus infecting bacteria. Eg,  λ phage, T2, T4, φ174, MV-11

2. Plant virus:

  • Those virus that infects plants. Eg. TMV, cauliflower mosaic virus

3. Animal virus:

  • Those virus that infects animals. Eg. Polio virus, Retro virus, Herpes virus, Adeno virus

4. Insect virus:

  • Virus that infects insects. Eg. Baculovirus, Sacbrood virus, Entomopox virus, Granulosis virus

 

Classification of virus on the basis of mode of transmission:

1. Virus transmitted through respiratory route:

  • Eg, Swine flu, Rhino virus

2. Virus transmitted through faeco-oral route:

  • Eg. Hepatitis A virus, Polio virus, Rota virus

3. Virus transmitted through sexual contacts:

  • Eg. Retro virus

4. Virus transmitted through blood transfusion:

  • Eg. Hepatitis B virus, HIV

5. Zoonotic virus:

  • virus transmitted through biting of infected animals;
  • Eg. Rabies virus, Alpha virus, Flavi virus

Classification of virus