Question

chapter 18 & 21 test
why is it difficult to develop vaccines for retroviruses?
○ their small size evades the immune system
○ rna mutates more frequently than dna
○ the capsid of the retroviruses is resistant
○ vaccines can only target blood-borne pathogens

Explanation:

Retroviruses have RNA genomes, and RNA has a higher mutation rate than DNA because RNA polymerases lack the proofreading ability of DNA polymerases. This rapid mutation means viral surface proteins (targets for vaccines) change frequently, making it hard to develop a vaccine that remains effective. The other options are incorrect: their size does not evade the immune system, their capsids are not inherently resistant to vaccine development, and vaccines can target non-blood-borne pathogens.

Answer:

RNA mutates more frequently than DNA