Researchers in the Journal Nature Medicine reported that they isolated a new HIV-1 virus, the type of HIV responsible for most cases of AIDS, in a woman from Cameroon who so far hasn’t show any of the signs or symptoms of AIDS. While there are three different types of HIV-1, M, N, and O, this virus would represent a new type, which is genetically similar to a related virus in gorillas called SIVgor. This is the first time that a virus similar to HIV has been believed to have been transmitted from gorillas to humans, prior types of HIV-1 including M, N, and O have been traced to chimpanzee to human transmission.
I believe that this is very concerning for several reasons, the first of which is that it unknown how the virus makes the transition from chimpanzees or gorillas to humans, although contact with infected meat from these animals is thought to be the culprit. Whatever the reason, it seems possible that transmission from chimpanzees and gorillas to humans may be ongoing, and that new strains of HIV could be introduced into the human population. This could complicate detection and prevention efforts, as well as make it very difficult for an HIV vaccine to be produced.
So far HIV vaccine production has been hampered by both the virus’s ability to replicate and mutate quickly, as well as the ability of HIV to infect cells of the very immune system cells that would mount the immune response to HIV. Researchers are assuming that this strain of HIV will behave similarly to other strains of HIV, and that it will respond to the same medications as other strains of HIV. This may likely be the case, however, standard tests for HIV-1 are not able to detect this virus, and therefore it is likely that more people than this single patient have this new strain of HIV. A big unknown is exactly how many people have this new strain of HIV.
While it is reported that this woman’s CD4 count is near 300 without medications, normal CD-4 counts are usually well above 500, and this woman does have immune suppression which could put her at a modestly increased risk for a variety of opportunistic infections. And of course, like other types of the HIV-1 virus, the woman’s condition could deteriorate such that she would need anti-viral medications. Doctors and researchers will doubtlessly follow her condition to see how this new strain of HIV-1 behaves.
While the presence of this new strain of HIV-1 complicates public health efforts, basic science research into how this virus affects the human body could be important in the fight against HIV/AIDS. If this type of HIV-1 is less virulent than other strains, then researchers might be able to figure out new points of vulnerability in the HIV virus.
Another interesting question is what would happen if this woman was exposed to one of the older strains of HIV-1, such as M, N, or O? Currently the strain that is infecting her is producing at a high rate, but if another strain of HIV-1 were introduced would it be able to compete with this new strain? Most likely the woman would then be infected with two strains of HIV, and it is very likely that there are several patients who have both this new strain, as well as older strain or strains of HIV-1 for which they are currently receiving anti-viral medications. It is very concerning when you consider the possibility that gorilla or chimpanzee reservoirs of new strains of HIV may exist which have not crossed over into the human population.
A nightmare scneario would be novel strain of HIV which could be spread by the respiratory system, and thus would spread as quickly as the flu and could infect with much larger percentages of the human population. Viruses such as Ebola, which are spread by contact, have a reservoir in animal species in Africa and occasional outbreaks occur when animals infect humans. What other forms of infectious diseases might be waiting to cross over to humans is currently unknown.
This is why I believe it is essential to begin funding more research into monitoring animal to human transmission of infectious diseases, which may include prevention efforts, in Africa and on other continents as well. Even the current H1N1 flu pandemic or “swine flu” may have been caused by transmission of a mutated and recombined version of this virus between pigs and humans. Although this has yet to have been proven, other strains, and subsequent pandemics of influenza in the past have occurred from transmission from a pig to a human.
Sources: http://www.nature.com/nm/journal/v15/n8/full/nm.2016.html, A new human immunodeficiency virus derived from gorillas. Plantier, J. C. et al. Nature Medicine 15, 871 – 872 (2009); New Strainof H.I.V. is Discovered Lawrence K. Altman, http://www.nytimes.com/2009/08/05/science/05hiv.html?hpw