Review Question - QID 216672

This variant that has the same genetic material as the wildtype virus but has a hybrid gene with material from 2 different chromosomes most likely underwent genetic recombination.

Viral mechanisms for creating large-scale diversity include recombination, reassortment, complementation, and phenotypic mixing. Recombination refers to the exchange of genetic material between 2 chromosomes within the same virus. This happens due to crossing over in homologous regions and creates hybrid genes. Reassortment occurs when different virus variants with segmented genomes exchange segments. Complementation occurs when 2 different viruses infect a cell and an active viral protein from the first virus compensates for a defective protein in the other virus. Finally, phenotypic mixing occurs when 2 different viruses keep their original genetic material but exchange coat proteins.

Incorrect Answers:
Answer 1: Antigenic drift occurs when point mutations occur in critical viral structures. These cause low level epidemics of viruses such as influenza and do not result in the creation of hybrid proteins.

Answer 2: Complementation occurs when 2 different viruses infect a cell and an active viral protein from the first virus compensates for a defective protein in the other virus. This does not result in changing the genetic material of either virus.

Answer 3: Phenotypic mixing occurs when 2 different viruses keep their original genetic material but exchange coat proteins. This does not result in changing the genetic material of either virus.

Answer 4: Reassortment occurs when different virus variants with segmented genomes exchange segments. The variant will not contain the same genetic material as either wildtype but it usually does not form hybrid proteins.

Bullet Summary:
Recombination refers to the exchange of genetic material between 2 chromosomes resulting in hybrid genes or hybrid chromosomes.