Smallpox immunization may confer protection against HIV, say researchers who suggest that the end of smallpox vaccination in the mid-20th century may have caused the rapid contemporary spread of HIV. The new theory, published in BMC Immunology, notes that vaccinia immunization, as given to prevent the spread of smallpox, produces a five-fold reduction in HIV replication in the laboratory.
In the study, Raymond Weinstein, a scientist at George Mason University in Virginia, together with a team of researchers from George Washington University and UCLA, looked at the ability of white blood cells taken from people recently immunized with vaccinia to support HIV replication compared to unvaccinated controls.
Smallpox immunization was gradually withdrawn from the 1950s following the worldwide eradication of the disease, and HIV has been spreading exponentially since approximately the same time period. Weinstein proposes that vaccination may confer protection against HIV by producing long term alterations in the immune system, possibly including the expression of a certain receptor, CCR5, on the surface of a person’s white blood cells which is exploited by both viruses.
“While these results are very interesting and hopefully may lead to a new weapon against the HIV pandemic, they are very preliminary and it is far too soon to recommend the general use of vaccinia immunization for fighting HIV,” cautioned Weinstein.