Explore how mutation, recombination, large population size and short life cycles drive viral evolution. RNA viruses often mutate rapidly because replication lacks proofreading; influenza antigenic drift and shift, and HIV reverse transcriptase errors, affect vaccines and treatments.
Pathogens are disease-causing organisms.
Outline two reasons for the very rapid rates of evolution in some viruses.
a. rapid rate of mutation;
b. in RNA viruses / retroviruses enzymes (RNA replicase/polymerases/reverse transcriptase) do not proofread or correct errors (unlike DNA polymerase);
c. exchange of genetic material with each other (in the same generation)/ recombination and horizontal gene transfer;
d. viruses have short generation times / high reproduction rates / reproduce/replicate fast;
e. transmission of viruses between species can lead to new strains;