Does reverse transcriptase have a function in healthy humans?

The human immunodeficiency virus (HIV, the cause of AIDS) and the human T-cell lukemia virus (HTLV) are both retroviruses. As such, they do not contain DNA but contain RNA genetic instructions. In order to infect a cell they require the enzyme reverse transcriptase to copy the RNA into DNA that then infects the host cell.

Many HIV antiretroviral therapies work by interfering with the functioning of reverse transcriptase, thereby preventing the virus from completing the infection cycle.

Does reverse transcriptase have a function in healthy human cells? Are there normal processes that can be blocked by reverse transcriptase inhibitors?

Yes, reverse transcriptases (RTs) have a some importance in 'healthy' humans. All humans express a RT called 'telomerase', which is a ribonucleoprotein that helps to protect our chromosomes from wear and tear. There are known inhibitors of human telomerase. I'm not sure that the effects of such inhibitors on humans has been studied to much degree. However, telomerase inhibitors are known to destroy replicating cells in vitro, and for this reason, some scientists have suggested that they might be useful in cancer therapy.

In addition to telomerase, we also have RTs that play a role in retrotransposon relocation. Retrotransposons, or 'jumping genes', are tracts of DNA that can literally move themselves around the human genome to new (and quite random) locations. The ability of these retrotransposons to reinsert themselves into the genome requires the work of RTs, which are usually encoded by the transposons themselves (although in some cases, viral RTs can do the job). Because of the randomness of their relocation, retrotransposons can create mutations. So, the importance of retrotransposons in 'healthy' humans is certainly debatable. Some feel that transposons may have been responsible for important evolutionary developments and others see them simply as pests that occasionally create unfavorable mutations. If I'm not mistaken, there are inhibitors for the RTs involved to retrotransposon relocation. However, I don't think they've been studied in vivo, and I highly doubt that inhibition of these RTs would have any effect on day-to-day human health.

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No, I don't think so, RT only works for retroviruses. I don't think that there are any processes that would be blocked, otherwise they couldn't sell the drugs to treat HIV, it wouldn't be safe.

Nope. Humans don't naturally have reverse transcriptase enzymes. That's why they are good targets for disrupting HIV.

Reverse transcriptase does have a function in healthy cells. Reverse transcriptase is actively involved in the process of DNA replication. Reverse transcriptase is used in DNA replication to convert DNA to RNA for the transcription process, which leads to the translation of RNA into amino acids, leading to the production of proteins. If we did not have reverse transcriptase, this switch from DNA to RNA would not occur, and there would be no proteins. The inhibition of protein formation would be something that would have to be seriously researched before the reverse transcriptase inhibitors could safely be sold on the market, because I am sure that it leads to several side effects, some which may deadly (depending on which proteins are inhibited by the lack of process).

No, reverse transcriptase (RT) is not found in humans. It is unique to the class of retroviruses, this is why RT inhibitors are such a great target for chemotherapy, because it has a much less degree of toxicity to the patient. The reason though that we can't cure HIV is because of its high mutation rate...

My genetics prof explained that there is on going research to use reverse transcriptase in future gene therapy. Right now I don't know of any natural processes as you described.