Research on chickenpox virus paves way for promising HIV vaccine

Scientists have long seen the chickenpox virus in vaccine form as a potential “vector” or carrier to deliver HIV genes and generate immunity to HIV, but safety concerns about this approach have limited further advances.

The new study is the first to show that chickenpox vaccine does not trigger an unwanted “HIV-welcoming” immune state in the genital mucosa – as was seen in a previous clinical trial that used a similar viral vector – or in the bloodstream.

“Our study investigated an important safety concern that posed a barrier to this vaccine strategy,” said Kelly MacDonald, a professor of immunology at U of T and of internal medicine, immunology and medical microbiology at the University of Manitoba. “The stage is now set to test a chickenpox-based HIV vaccine.”

The Journal of Clinical Investigation published the paper online on Jan. 22.

The researchers conducted their study in Kenya, a country severely affected by the HIV epidemic. Study participants were 44 healthy, HIV-negative women who were at low risk for HIV exposure and tested positive for immunity to chickenpox.

Lead author and U of T post-doctoral researcher Catia Perciani worked with researchers from the Kenya AIDS Vaccine Initiative-Institute of Clinical Research at the University of Nairobi to give study participants a high-dose vaccine against only chickenpox virus. The researchers then tested each participant’s blood, as well as mucosal cells from the cervix and rectum at intervals of four, eight and 12 weeks.

The key finding was that 12 weeks post-vaccination, there was no significant difference in the frequency of activated HIV target cells, compared to pre-vaccination.