Vaccine Prompts HIV Antibodies In 97% Of People In U.S. Study
A two-dose HIV vaccine generated antibodies against the virus in 35 out of 36 people (97 percent), with no severe side effects.
Photo Insert: Developing an HIV vaccine is particularly difficult because the virus rapidly mutates into new strains, which somewhat evade immunity.
The early-stage trial was designed to demonstrate safety and a proof-of-concept for a relatively novel approach to HIV vaccination, Carissa Wong reported for New Scientist.
It is unclear whether the vaccine protects against HIV. Based on the antibody levels generated by the two-dose regimen, booster doses are expected to be required. Developing an HIV vaccine is particularly difficult because the virus rapidly mutates into new strains, which somewhat evade immunity.
As a result, many groups of researchers are seeking to develop vaccines that stimulate a type of immune cell called B-cells to generate so-called broadly neutralizing antibodies. These work against parts of the HIV virus that vary little between strains.
During any viral infection, a fraction of B-cells that are specific to the virus make broadly neutralizing antibodies. When it comes to HIV, using viral proteins in a vaccine may activate this subset of B-cells.
To assess this approach, Juliana McElrath at the University of Washington in Seattle and her team recruited 48 volunteers without HIV to test a vaccine that stimulates B-cells to make HIV-specific neutralizing antibodies.
The vaccine contains part of a protein found on the surface of HIV, called gp120, which helps the virus enter cells.
Thirty-six of the participants were given either two low or two high doses of the injected vaccine, administered two months apart. The remaining 12 volunteers, acting as the control group, received a saline solution. After the injections, all the participants regularly provided blood samples for 16 weeks.
Of those who received either the low or high vaccine doses, 97 percent had HIV-specific broadly neutralizing antibodies at the end of the study. Antibody levels were similar across the participants who received either the high or low vaccine doses, but marginally higher among those who had the high doses.