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Drug resistance development possibilities?
Mar 15, 2006


We are two HIV+ guys living together and we are having sex without condoms. My boyfriend is on drugs and he's virus is undetectable. So we are just wondering that what are the odds for the case that I get a virus from my boyfriend and it develops drug resistance against the drugs my boyfriend is using after entering my body? Or what are the odds for that that my boyfriend has drug resistance strain already in his body despite the fact that his virus has been undetectable already for for two years?

Thanks for your answer..

Response from Dr. Sherer

What have your doctors advised? I would start my answer by urging you to talk to your doctor or doctors about this issue, as the facts can change over time, and its difficult for you to give me all of the information I would need to advise you in this type of internet forum.

You are asking whether HIV superinfection - i.e. infection with a second strain of HIV while already infected with one - occurs, and, in your situation, i.e. one partner on ART and the other untreated - whether you are exposing yourselves to an additional risk of drug resistance.

First, it is clear that HIV superinfection can occur. Specific cases are well documented. For this reason, current guidelines and most HIV physicians advised their patients to continue to practice safe and safer sex practices, i.e the consistent use of latex condoms.

There is more to this discussion, however. It's striking in the literature, and among those who study superinfection, how uncommon and even rare it appears to be, for unclear reasons.

There is also evidence that the risk of sexual transmission is significantly reduced in people on ART with viral loads below detection, though that risk is not zero.

For these reasons, some discordant couples, i.e. in whom one partner is positive and the other is HIV negative, choose to accept these odds and practice unsafe sex. (I have such patients in my practice, and they make this choice against my advice.)

And the same is true for couples in your situation, i.e. one positive and on ART with good control (ie viral load below detection for a prolonger period), and the other not on ART. In spite of current recommendations, some couples choose to practice unsafe sex.

My answer to this question might vary, depending on your (i.e. the author of the email's) viral load, as the risk of superinfection of your partner increases with higher levels of viral loads. My answer also may vary some time in future, when your partner is no longer well-controlled, and has uncontrolled viremia, possible at a time when they have developed resistance mutations.

There is very clear evidence that transmission of virus with such resistant mutations occurs, at present in about 10-15% of new HIVinfections in the United States. So you are correct to be concerned about this possibility. To my mind, this possibility should lead you (and other couples in a similar situation) to reconsider the use of latex and the practice of safer sex, which many have been able to adjust to without sacrificing intimacy or sexual gratification.

To make this answer more complicated, and to underscore the reason that you need to talk to your own doctor(s) about this issue, there is far more to HIV sexual transmission than just the level of HIV in the blood, which is the measurement that your doctor obtains on a regular basis. HIV sexual transmission is also related to the level of HIV in your, and your partner's, sperm and semen. And that level is variable, and does not always correlate with the level of virus in your blood.

And finally, the same is true about resistance, and the evolution of resistance. While your partner may have an undetectable viral load in his blood, there may still be viral evolution in sequestered sites in his body, such as the central nervous system and the genitals. Hence resistance may occur in genital secretions that does not lead to virologic failure in the blood. The extent to which this phenomenon contributes to transmitted drug resistance is unknown.

So the answer to your simple question is not at all simple. I advise patients to err on the side of caution, and protect each other to the greatest degree possible. Living with HIV has improved considerably in the past decade, but it is still rough. I don't want patients to underestimate living with the virus, or to make things harder for themselves. This advice implies living with condoms and learning how to be sexy and satisfied with latex. Many couples figure out how to do this; the problem is that there are too many unknowns when an alternative choice is made.

Is it time to change meds
Is there a possibility of drug resistance?

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