By Barry C. Fox, M.D., University of Wisconsin
What is being done for HIV prevention to keep people from getting the diseases in the first place? Since HIV is so difficult to treat once the virus is acquired, and since management requires lifelong attention, the ideal means to manage HIV is through prevention. Let us take a look at some of ways to prevent the spread of HIV.
Blood Safety
Since medical professionals are exposed to blood the most, and since HIV may be transmitted from blood contamination, avoiding blood spatter is common sense. This is why you see first responder emergency personnel and medical providers wearing equipment such as gloves and face shields for protection. This is part of universal infection control precautions.
Realistically, HIV acquisition would require an open break in the skin or splash to the eyes, but sometimes skin cuts could be small enough to go unnoticed. Since the main transmission of HIV is by sexual contact through secretions, means to reduce direct contact with infected fluids is a priority.
This is a transcript from the video series An Introduction to Infectious Diseases. Watch it now, on Wondrium.
Public Health Education
In the U.S., there has always been an outcry for safe sex, which involves barrier precautions not only to prevent HIV transmission, but also other sexually transmitted diseases. But this concept is not embraced by many countries and cultures. In very general terms, the CDC has launched a strategy for HIV prevention called the Serostatus Approach to Fighting the Epidemic, abbreviated SAFE. This program is mostly meant for public health education.
We know that adherence to ART will reduce the viral load in blood and body secretions, and statistically will reduce the risk of an infection transmission. This concept has been extended to HIV-positive women who want to deliver their babies by natural childbirth. If the woman is taking ART and her blood viral load is less than 1000 copies/ml, the baby is at very low risk of HIV acquisition, and vaginal delivery is allowed. Otherwise, C-section is the recommended means of childbirth.
Preventative Strategies
A number of special preventative strategies have been adopted for other cultures. While not acceptable for all cultures, we know that male circumcision reduces the risk of HIV transmission. Testing of sexual partners to see if there is sero-discordance, with one partner positive for HIV and the other one negative could be important to prevent HIV transmission, although many people just don’t get tested.
The CDC and World Health Organization have recommended a strategy known as pre-exposure prophylaxis, or PrEP for those who are at high risk of acquiring HIV. This includes sero-discordant couples, couples not using condoms, and injection drug users who share needles. This means the non-infected partner takes a limited ART regimen daily, not just before a high-risk encounter. When medications are reliably taken, the risk reduction may be as high as 90 percent.
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PEPFAR
Control of HIV nationally and worldwide obviously also requires extensive financial support. So what role is the U.S. playing internally and worldwide? The U.S. has a master plan called PEPFAR, the President’s Emergency Plan for AIDS Relief. This program targets resource-poor countries that are hit hardest by the HIV pandemic, and is mostly coordinated by the CDC.
PEPFAR is committed to supporting 6 million AIDS patients who are in treatment, and providing drug therapy for their lifetime for 1.5 million pregnant women and their babies.
We must face the fact that in spite of all the HIV prevention efforts, a vaccine will be required to end the global HIV-1 pandemic. The challenge in the development of such a vaccine appears unprecedented. A vaccine that is modeled using classic vaccination concepts remains the ultimate goal for HIV.
BnAbs Against HIV
The development of a vaccine would produce broadly neutralizing antibodies, or BnAbs, which could potentially halt primary infection, and this is a priority. The exact antigenic protein, or combination of proteins, to target for these antibodies has been elusive so far.
We do, however know that BnAbs are produced in HIV infected individuals, but unfortunately not for several years. We are not yet sure how to speed up this process. Also, in contrast to the relative ease of producing influenza vaccines, the genetic diversity and mutational capacity of HIV is much greater than that of influenza. This creates a larger challenge to attaining a vaccine.
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Vaccine Solutions
HIV rapidly integrates into the CD4 genome and establishes latent reservoirs of the virus. Any vaccine would also need to produce other T-lymphocytes that would control these latent sites. This goal may not be achievable with the first vaccination attempts.
Instead, the first vaccine may need to be designated to reduce HIV viral levels and preserve uninfected CD4 cells. As we know from our study of ART, the natural history of HIV infection shows that viral blood burden correlates with disease progression. Reducing viral RNA by one or more logarithms should slow disease progression.
CD4 Genetic Manipulation
What other strategies are being tried in the meantime? Some have turned their focus to modifying the genes of host CD4 cells to make them resistant to infection. It is also known that a small percent of humans lack a receptor on their CD4 cells, the CCR5, and are actually immune to HIV. Conceptually researchers are targeting the CCR5 gene in stem cells to make the CD4 cells automatically lack the CCR5 receptor, and naturally block infection.
Now as farfetched as this may seem, the first person considered cured of HIV, known as the Berlin Patient, received a stem cell transplant in 2008 to treat his leukemia, from a donor who had a genetic abnormality called CCR5 delta 32 mutation. That made him naturally resistant to HIV. He is thought to be the only person cured of HIV.
However, HIV and AIDS will continue to be an elephant on the back of the world as we struggle to control it.
Common Questions about HIV Prevention
The CDC has launched a strategy for HIV prevention called the Serostatus Approach to Fighting the Epidemic, abbreviated SAFE. This program is mostly meant for public health education.
The CDC and World Health Organization have recommended a strategy known as pre-exposure prophylaxis, or PrEP for those who are at high risk of acquiring HIV from partners. The non-infected partner takes a limited ART regimen daily, not just before a high-risk encounter. When medications are reliably taken, the risk reduction may be as high as 90 percent.
BnAbs, broadly neutralizing antibodies, are produced in HIV infected individuals. The development of a vaccine for HIV would aim to produce BnAbs, which could potentially halt primary infection.
