How does the proofreading mechanisms in viruses affect the frequency of the mutations a virus typically undergoes?

Explanation:

DNA polymerases are the enzymes that build DNA in cells. DNA polymerase also proofread their work to check for any error the process of which is called proof reading.

If the polymerase detects that an Incorrectly paired nucleotide has been added, it will remove (splicing) and replace the nucleotide with the correct one before it continues with DNA synthesis.

Mismatch repairing also corrects other errors that omit proofreading. They fix mismatched base pairs, replace some insertion and deleted base pair that can result into mutations.

When an error is corrected the rate of mutation is reduced this is because mutation results from error during the DNA formation process either through Insertion of a wrong nitrogenous base, or deletion leading to formation of an entirely new amino acid sequence that result into abnormal phenotype.