Response from Dr. Sherer

Not all HIV drug resistance is the same, and 3TC resistance with the M184V mutation is an excellent example.
Like other resistance mutations, the M184V impairs the ability of 3TC to reduce HIV replication.
On the other hand, 3TC still exerts an antiviral effect of about 0.5 log decline in the presence of the M184V mutation, so it retains some of its antiviral effect.
Also, the M184V mutation confers a large effect on the 'fitness' of HIV, i.e. it reduces the virus' ability to replicate.
For these latter two reasons, many physicians continue to use 3TC even in the presence of the M184V virus.
In your case, 3TC is still offering you benefit, and it is unlikely to be doing you any harm, so it can still safely be part of your treatment regimen.
However, you and your doctor may want to consider other options for your ART, knowing that the potency of the regimen has been mildly weakened. It is possible that you could develop resistance to this regimen, e.g. to the efavirenz, in a short period of time, so prompt consultation with your doctor on this question makes sense.
However, the fact that you have the M184V virus on your baseline resistance test makes it more likely that you acquired a virus with this mutation, rather than developing it spontaneously. This mutation is very common among transmitted resistance mutations.
What you and your doctor might choose as an alternative depends on what is available in your region. Options include intensification with another NRTI like abacavir or tenofovir, or switch of both the NRTIs and the other drug in the regimen.
You and your doctor may also choose to observe your response to this regimen before making a change. It is quite possible that this regimen would be effective in controlling your virus without any further change, in spite of the presence of the M184V mutation.
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