Strategies to fight the AIDS virus include drugs that mimic nucleotides, called nucleotide analogs. Reverse transcriptase incorporates these analogs into the newly formed viral DNA strand. The host cell cannot interpret the DNA correctly, so the virus does not propagate. Unfortunately, this therapy only works for a short time in infected individuals, probably because:
|A||the outer protein coat of the virus mutates so it is no longer recognized by the immune system.|
|B||the patient’s immune system starts to fight off the analog.|
|C||the reverse transcriptase mutates to prevent incorporation of the analog.|
|D|| the viral DNA no longer incorporates into the host DNA.|
The action of the analogs is at the level of reverse transcription. If the reverse transcriptase mutates to no longer allow incorporation of the analogs, then the virus can continue on its normal path. It is unlikely the body would mount an immune response to these analogs (choice B) as these analogs are so similar to normal nucleotides. Although the outer protein coat can and does mutate (choice A), this has nothing to do with the analogs. And the virus must incorporate into the host chromosome, so choice D is also incorrect.