HIV antibodies revived as microbicide

A study reported online by Nature Medicine claims the first evidence of protection for female macaques against infection with an SHIV, from topically applied anti-HIV antibodies.

A research group led by Dr John Moore at Cornell University found that applying 5mg of a broadly-neutralising monoclonal antibody against HIV (with the codename b12) two hours before monkeys were vaginally exposed to an SHIV virus with an HIV outer coat seemed to protect most of the monkeys from infection. Among monkeys treated with the antibody, 3 out of 12 became infected. In a control group, 12 out of 13 were infected (Veazey).

A biotech company called Epicyte in San Diego, California, is reported to be developing a system for producing this antibody in genetically engineered plants, which would allow it to be made cheaply in large quantities.

While previous studies have found that injected antibodies are able to provide significant protection against exposure to SHIV across mucosal surfaces, there was no protection against infection when antibodies were applied to the surface or pre-incubated with the virus (Lewis).

A variety of microbicide candidates have been shown to protect monkeys against viral challenges. However, their effectiveness in humans remains to be proven. A substance that is to act as either a chemical or physical barrier against infection must be present in the right amounts, at the right place at the right time. To protect against HIV transmission during sexual contact, this means that the way a product is formulated and applied is likely to be just as important as the nature of the 'active ingredients'.

A further issue with all microbicides is that they must be safe for long-term use, without causing inflammation or other damage to tissues that could make people more vulnerable to infection with HIV and other diseases.

There is further discussion of microbicide development on aidsmap here. Links to external sources of information are listed here.