A few updates on HIV research

Anti-HIV antibodies as therapy
Some rare patients who get infected with HIV are able to control their infections using their own immune systems. These patients are able to produce some broadly neutralizing antibodies (bNAbs).These antibodies can protect a patient’s healthy (uninfected) cells.antibodies recognize the protein called the “envelope spike” that is present on HIV and prevent the virus’ entry into cells.

HIV virus attacking cell. 3D render, via Shutterstock.

HIV virus attacking cell. 3D render, via Shutterstock.

Much of the spread of HIV to normal cells occurs as the virus particles drift past the CD4 cells and then come into contact with them. The bNAbs are effective in blocking the virus and thus prevent HIV from entering the cell. However, HIV can also be spread from one infected cell to another by direct contact. bNAbs wouldn’t be effective in this case, so the virus would continue to spread. While bNAbs could be helpful in slowing the spread of HIV in a given patient, they couldn’t stop it completely. They would be a weapon in the anti-HIV armamentarium, but not silver bullets in and of themselves. At least, that’s what people thought initially.

Recently, researchers at Rockefeller University and Caltech have found one type of bNAb that does more. It can prevent both types of infection: the virus that is flowing past the CD4 cell as well as the virus that is spread by contact from one cell to another. This bNAb, 8ANC195, could be used to essentially stop the spread of HIV in an infected human, maintaining his other CD4 cells in their native, pristine state. Then other drugs (antiretrovirals, other antibodies, other drugs) could be used to wipe out the remaining HIV in the patient over time.

A clinical trial using bNAbs is underway. It is not using 8ANC195, but that antibody may be used in a trial in the near future.

Possible anal/vaginal gel for prevention of HIV

HIV-infected semen is the most common way that the disease is spread. Researchers are working on a technique to neutralize (destroy) HIV in semen and thereby prevent infection. Free HIV particles are present in semen, but the structural composition of semen helps to “hide” the HIV from drugs that might otherwise destroy the virus (viricides). The ejaculate contains amyloid fibrils that are sticky, tenacious strands that, because of their physicochemical structure, can protect the virus and keep drugs at bay.

Researchers from Ulm University in Germany and from the University of Pennsylvania are working with a chemical, CLR01, that could be very effective as a viricide. The chemical is capable of quickly killing HIV by destroying the membrane that surrounds it. It also attacks any amyloid fibrils that are already formed and hinders the production of new fibrils. Thus, it lays bare the HIV particles to be neutralized. As an additional benefit, CLR01 seems to be capable of destroying any enveloped virus, like HIV. So CLR01 may be effective against other viruses like influenza, Ebola, Hepatitis C and HPV. To prevent sexually transmitted infections, CLR01 would be formulated as a gel that can be used anally or vaginally.

Of course, the above two drugs are still in research, development and/or clinical trials. They are not available yet. Depending on the results of these and other studies, they may be available in the future.

strong>New PrEP data
A study from Kaiser Permanente showed that, in a group of sexually active patients taking PrEP (Truvada) there were no cases of HIV detected during the course of the study. The study enrolled a group of about 650 patients, most of whom were gay or bisexual men who tested negative for HIV. They were placed on PrEP and counseled, and every three months they were tested for sexually transmitted infections (STIs), including HIV.

At the end of a year, no patients had become HIV positive. However, quite a few did contract other STIs over the course of the year. These other STIs may be related to the patients’ use of PrEP or they may be unrelated. For example, some could have not used condoms and thereby gotten infected with gonorrhea, syphilis, chlamydia, etc.

The authors feel that PrEP works and primary care physicians should discuss the use of PrEP with all of their patients at risk for HIV.

Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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