Viral Classes

Question 1

Class I

Answer 1

Adenovirus, Herpes,Pox

dsDNA

rep within nucleus (except pox) and use host mechs

pox=large, has own enzymes for rep, does so in cyto

viral enzymes for rep made first, DNA rep, then structural components last

Question 2

Class II

Answer 2

parvo, circo

ssDNA

some rep autonomously, some use helper virus

rely on cellular DNApoly

Question 3

Class III

Answer 3

Birna, Reo

dsRNA

carries its own RNA-dependent RNApoly

Question 4

Class IV

Answer 4

calici, corona, flavi, picorna, toga

+ve sense ssRNA

code for all replicative functions, RNA is infectious itself

codes for non-structural proteins (RNA polymerase) that can make -ve complement for further translation and assembly

Question 5

Class V

Answer 5

arena, bunya, filo, orthomyxo, paramyxo, rhabdo

-ve sense ssRNA

carry own RNA-dependent RNApoly

Question 6

Class VI

Answer 6

retrovirus

+ve ssRNA, but rep takes place as dsDNA intermediate

reverse transcriptase (RNA-dependent DNApoly)

RT makes complement DNA strand, RNase removes original ssRNA strand, RT acts as DNApoly to make dsDNA strand, integrase puts it in the host DNA

Question 7

Class VII

Answer 7

Reversiviruses (hepadna)

replication involves DNA genome rep’d via RNA intermediate

genome is partial ss and partial ds