Question

Why would you predict that zoonotic viruses are almost always RNA rather than DNA viruses? (SELECT ALL THAT APPLY--MORE THAN ONE CORRECT ANSWER POSSIBLE)

A. Like cellular life, viruses face limitations imposed by having to re-purposes existing traits when entering a new environment.

B. RNA viruses generally have higher mutation rates than DNA viruses.

C. Because mutational changes in a genome may create the variation required for adaptation to a new environment.

D. Viruses face the same difficulties that cellular life faces in terms of success and reproductive fitness.

Answer 1

RNAs have enormous diversity and high rates of evolution as compared to DNA. Nearly 89% of human-infective species are zoonotic while the remaining too have zoonotic origins. Compared to DNA, RNA needs a host for replication due to which it need to have high evolution of transmissibility (for easy transmission followed by replication) during human infection. Not only this, RNA viruses have high levels of genetic variation (and thus evolve at a fast rate) and hence are termed as quasi-species. Nucleotide substitution rates in fast-evolving RNA

Thus, options A, B and C are correct