Washington D.C., July 24: A new study has zeroed in on a new defence against HIV-1, the virus that causes AIDS. The team of researchers at Texas Biomedical Research Institute used an animal model, to show for the first time that an antibody called Immunoglobulin M (IgM) was effective in preventing infection after mucosal AIDS virus exposure.
Scientists first treated the animals with a man-made version of IgM, which is naturally produced by plasma cells located under the epithelium (the surface lining of body cavities). Half an hour later, the same animals were exposed to SHIV (simian-human immunodeficiency virus). Four out of the six animals treated this way were fully protected against the virus. The animals were monitored for 82 days.
"IgM has a high affinity for its antigens and grabs them very quickly and does not let go. Our study reveals for the first time the protective potential of mucosal anti-HIV-1 IgM. IgM has a five-times higher ability to bind to virus particles compared to the standard antibody form called IgG. It basically opens up a new area of research. IgM can do more than it has been given credit," explained DR. Ruth Ruprecht, a researcher.
The team then found that applying the IgM antibodies resulted in what is called immune exclusion. IgM clumped up the virus, preventing it from crossing the mucosal barrier and spreading to the rest of the body. The technique of introducing pre-formed antibodies into the body to create immunity is known as passive immunization.
Worldwide, an estimated 90% of cases of HIV-1 are caused by exposure in the mucosal cavities like the inside lining of the rectum or vagina.
The findings appeared in the Journal of AIDS.