Essential Knowledge 3.C.3

Viral replication results in genetic variation, and viral infection can introduce genetic variation into the hosts.

Viral replication differs from other reproductive strategies and generates genetic variation via various mechanisms. Viruses have highly efficient replicative capabilities that allow for rapid evolution and acquisition of new phenotypes. Viruses replicate via a component assembly model allowing one virus to produce many progeny simultaneously via the lytic cycle. Virus replication allows for mutations to occur through usual host pathways. RNA viruses lack replication error-checking mechanisms, and thus have higher rates of mutation. Related viruses can combine/recombine information if they infect the same host cell. HIV is a well-studied system where the rapid evolution of a virus within the

host contributes to the pathogenicity of viral infection.

The reproductive cycles of viruses facilitate transfer of genetic information. Viruses transmit DNA or RNA when they infect a host cell. Examples include transduction in bacteria and transposons present in incoming DNA. Some viruses are able to integrate into the host DNA and establish a latent (lysogenic) infection. These latent viral genomes can result in new properties for the host such as increased pathogenicity in bacteria.

Students should be able to:

LO 3.29 Construct an explanation of how viruses introduce genetic variation in host organisms.

LO 3.30 Use representations and appropriate models to describe how viral replication introduces genetic variation in the viral population.