Concurrent rise in HIV and eradication of smallpox may be key to HIV resistance

A vaccine to prevent HIV or a cure for AIDS has been a medical holy grail since the disease emerged with a vengeance in the late 70s and early 80s.

Treatment protocols for patients who carry the virus that causes AIDS have progressed rapidly since the virus became known as an indiscriminate killer in the past few decades, but what if we’ve been sitting on the answer all along? Researchers at UCLA and George Mason University in Manassas, Virginia have made preliminary discoveries that indicate the decline in use of the vaccine for smallpox, vaccinia, may have inadvertently allowed HIV to grab a foothold on humanity.

Let’s start with a fun fact about HIV: to infect white blood cells, most strains need to be able to latch onto a protein on the cells’ surface called CCR5. Many people of European descent have a mutated version of CCR5, and resist HIV as a result…

Fascinatingly, (researchers) found that lymphocytes from people vaccinated up to six months earlier – or in preliminary results from a much larger study, 14 months – were up to 10 times less likely to be infected by HIV strains that need to use CCR5. Viruses like measles only interfere with HIV as long as they are there causing their particular disease, but the effect of the vaccinia virus seemed to last months.

The researchers conclude that vaccinia prevents HIV – and that once smallpox was eradicated, and smallpox vaccination wound down, HIV surged as a result.

A news release about the findings, published in the May 17th issue of BMC Immunology, discusses the theory:

“There have been several proposed explanations for the rapid spread of HIV in Africa,” Dr. Raymond Weinstein of George Mason U. said in a news release. These include “wars, the reuse of unsterilized needles and the contamination of early batches of polio vaccine,” he said.

“However, all of these have been either disproved or do not sufficiently explain the behavior of the HIV pandemic,” he said. “Our finding that prior immunization with vaccinia virus may provide an individual with some degree of protection to subsequent HIV infection suggests that the withdrawal of such vaccination may be a partial explanation.”

The piece linked above in New Scientist goes on to suggest that perhaps the smallpox virus itself, and not the vaccine to prevent it, was providing the inadvertent protection against HIV infection. Although the exact reasons behind the fall of smallpox and concurrent rise of HIV infections worldwide remain to be seen, this particular study could eventually prove very valuable in preventing HIV-related deaths.