Question

what is the broadest classification currently used for all viruses?

Answer 1

The Baltimore classification is the broadest classification of virus. It was devised by Nobel laureate David Baltimore. The viruses are classified on basis of their genomic configurations.

Group I = Viruses with double stranded DNA. Herpes virus, pox viruses

Group II= Viruses with single stranded (+) DNA.

Replication involves the formation of a (-) sense strand. This strand is a template for (+)strand RNA and DNA synthesis. Parvoviruses

Group III= Viruses with double stranded RNA

Segmented genomes are present with monocistronic mRNA produced from each segment. Reoviruses

Group IV= Viruses with single stranded (+) RNA

Polycistronic RNA is produced that is infectious. A polyprotein is formed which is cleaved to form different proteins. Picornaviruses, hepatitis virus. The genomic RNA is formed from one to two rounds of translation.

Group V= single stranded (-)RNA with an antisense orientation

This RNA is converted to positive sense RNA by RNA dependent RNA polymerase, which is used to produce proteins. They can be segmented or non-segmented viruses. Rhabdoviruses

Group VI= Viruses with single stranded (+) sense RNA with reverse transcription of a ds DNA intermediate.

RNA genome is diploid and is used as template for reverse transcription. Retroviruses.

Group VII= Viruses with a single stranded RNA replication intermediate.

Reverse transcription occurs outside the virion upon maturation. Hepadnaviruses

Except groups VI and VII, all other groups have substantial similarities in genome organization and replication.

The other Broad classification of viruses used is the ICTV classification by International Committee on Taxonomy of Viruses. It has

Order: virales

The seven orders are the Caudovirales, Herpesvirales, Mononegavirales, Nidovirales, Picornavirales and Tymovirales and Ligamenvirales

Family: viridae Ex Mycoviridae

Subfamily: virinae

Genus: virus Ex; T4 like viruses

Species: virus Ex: Enterobacteria phage T4