Most new HIV infections worldwide are caused by mucosal contact with HIV. Immunoglobulin M (IgM) is the first antibody produced by the immune system in response to infection, and IgM is present in the circulatory system and mucus (secreted IgM). Scientists in the Department of Virology and Immunology at the Texas Institute of Biomedical Research are studying the role of IgM in preventing HIV infection.
Related research results were recently published on AIDS. The researchers obtained recombinant multimeric monoclonal IgM by neutralizing the monoclonal IgG1 antibody 33C6-IgG1, and conducted in vitro tests. They received recombinant IgM therapy in red-tailed monkeys through passive rectal administration, and then infected these red-green algae monkeys with Simian Human Immunodeficiency Virus (SHIV, carrying the HIV-1 capsid gene) through enteral administration. The researchers found that compared with 33C6-IgG1, which inhibits SIV infection, 33C6-IgM can capture the virus more effectively in vitro, and the IC50 level is significantly reduced. The IgM also showed higher affinity and binding power. After enteral administration, 33C6-IgM successfully prevented 4 red lizards infected with high-dose SIV from developing viremia (6 in total), and 6 out of 6 were treated with 33C6-IgG1.
When 5 red lizards are 5 times the 33C6-IgM, and all the controls have severe viremia, the same effect can be obtained. In breakthrough infection red-tailed monkeys passively immunized with 33C6-IgM, the early development of their own neutralizing antibody response is very obvious. Generally, data from primate models in this study demonstrated for the first time that mucosal IgM can prevent transmucosal HIV infection. This helps prevent HIV and develop vaccines.