I tested HIV+ two months after a needle stick and now am being asked by my employer to do Genotyping and Phenotyping to compare my virus to the patients whose blood I was exposed to. My treating doctor has suggested that this is simply not a accurate way to tell. He believes the virus mutates too frequently for this to work. Do you think these tests are dependable for this purpose? It has been six months since my test came back positive. I was originally on Crixivan and Combivir, then Viramune, Zerit and Retrovir, now I am on Sustiva, Zerit and Videx. I would appreciate your opinion in this matter and also if you know where I can find literature to support your opinion.

If there were blood stored from the source patient at the time of your exposure and your blood from that time as well, one might be able to look at the genetic fingerprints of the two viral strains and see whether they were identical. One could look at the pol gene (the subject of genotypic resistance analysis) or the envelop gene (the outer coat of the virus). With each passing day after infection, the virus begins to change (mutate). Since you have been on a few drug regimens since exposure, your virus has seen further evolution because of drug exposure. In my opinion, it would be impossible to determine now whether the viral strains were the same or not. MH