Question

How is the replication of the viral genome of retroviruses unique among the viruses?

Essay question I would like key concepts explained please !

Answer 1

Retroviruses were so named after the discovery of a key enzyme, reverse transcriptase, by
Drs Howard Temin and David Baltimore,This diverse group of RNA viruses replicate via reverse transcription (synthesize a DNA copy of their RNA genome during their replicative cycle). The genome is diploid, consisting of a dimer of two molecules of linear positive-sense, single-stranded RNA, each 7–11 kb insize.

Virus replication

During replication, viral reverse transcriptase transcribes DNA from virion RNA following the formation of long terminal repeats; linear and circular double-stranded DNA is formed and linear DNA forms integrate into cellular chromosomal DNA as a provirus, throughthe action of a virally encoded integrase enzyme and host-cellDNA repair mechanisms. In productive infections, virions assemble at and bud from theplasma membrane. Thus the retroviruses can remain in three forms

1 endogenous- as provirus

2 exogenous replication competent- are replication competent and have a standard complementof gag, pol, and env genes

3 exogenous replication defective-dependent on the helper activity of a replication-competent virus tocomplete the replication

Key biological features of retroviruses include: ability to acquireand alter host-derived genetic sequences; ability to integrateinto host-cell genome; activation or inactivation of specificgenes near integration site; ability to undergo mutation and recombination; can be used to generate vectors to deliver genes.