Viral Evolution

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Genetic Variation: viruses evolve because their gene pool changes over time, allowing them to evolve faster than the host. the rate of evolution of viruses is much faster than humans due to their shorter generation time, higher production rate, larger population size within a host, & genetic variation.

This rapid evolution allows viruses to adapt quicker to changing environments & evade host immune responses

Natural Selection: heritable traits that help replicate a virus become more common in the population, gradually. (Natural Selection requires genetic variation).

Recombination / Co-Infection: two strands of a virus infect one host cell simultaneously. the segments of the two strands get mixed up.

a. Exchange: pieces of DNA are exchanged by being broken up and put back together

b. Reassortment: entire segments are swapped

The unique combination of segmented genome, high mutation rate, and epidemiological factors makes Influenza viruses adaptable and prone to genetic reassortment. Influenza has strands with pandemic potential, worsening disease control

Pigs (influenza) can mix two different flu strands inside themselves, making one big flu.

Mutation: a permanent change in the genetic code of virus

During replication, a mutation is a mistake while making a copy.

RNA (single strand) = high mutation rate DNA = lower mutation rate

RNA lack proofreading mechanisms during replication, leading to more mutations