HIV link to smallpox hypothesised

The exponential spread of HIV infection may be linked to the eradication of smallpox 30 years ago, as immunisation with vaccinia, the vaccine used against smallpox, may also have provided protection against the HIV virus, according to a study published in the journal BMC Immunology.

The study authors claim that the behaviour of the HIV pandemic is insufficiently explained by the currently proposed theories, including contamination of polio vaccine and the reuse of unsterilised equipment, but that the rise of HIV infection coincides with the eradication of smallpox. The researchers therefore compared HIV-1 susceptibility in peripheral blood mononuclear cells in vaccinia vaccine-immunised patients with vaccine-naïve patients.

Cells of subjects who had received the vaccinia virus in the preceding 3–6 months were up to five times less likely to demonstrate replication of the HIV virus, compared with cells from unvaccinated subjects. Adding autologous serum increased HIV replication in unvaccinated subjects, but not in vaccinated subjects.

The authors concluded that prior immunisation with the vaccinia vaccine may provide some degree of protection against HIV infection or progression, though further studies need to be conducted before the vaccine is recommended for fighting HIV.