The vaccine, containing protein derived from the viral coat, tricks the body into thinking HIV has infected it. That triggers the production of antibodies which neutralise the virus and prevent vital immune system cells sticking together in useless clumps. Overall, the immune response was greater than that achieved with other, similar vaccines in human trials, according to a report in tomorrow's issue of the Lancet.
Dr David Schwartz, of the Center for Immunisation Research at Johns Hopkins University in Baltimore, and colleagues, say it is the first time that 'consistent induction of HIV-1 (a viral strain) neutralising . . . antibodies . . .' has been shown in man. The quantity of antibody produced increased with the dose used, confirming that the vaccine was having a direct effect on the immune system.
The vaccine (IIIB- rgp120/HIV-1), which had previously been tested on chimpanzees, was given as a series of three intra-muscular injections to 20 healthy volunteers. Antibodies appeared in nine out of ten volunteers two weeks after they were given the final high-dose vaccine, compared with five out of nine who received a low-dose form.
The vaccine also induced the production of immune system cells known as memory T cells, which enable the body to recognise 'foreign' proteins, such as bacteria and viruses.
There are about 20 Aids vaccines now in development.Reuse content