Antibody Building: Does Tapping the Body’s Other Immune System Hold the Key to Fending Off HIV Infection?

From Scientific American:

Discovery-of-new-antibodies-hiv_1 Scientists at the National Institutes of Health have identified long-sought and elusive broadly neutralizing antibodies to HIV in a pair of papers published in the July 9 issue of Science. These proteins produced by the innate immune system are crucial for creating a preventive vaccine, and could also have therapeutic uses developed in the coming years or decades. Variations in individuals' innate and adaptive immune systems can dramatically affect responses to infection—HIV is no exception. The result generally can be shown as a bell curve, with a group of people whose disease progresses rapidly, a broad middle segment who progress typically, and a small group of “elite controllers” whose immune systems are quite effective at containing HIV viral replication. The quest to figure out why has focused primarily on the adaptive immune system, because CD4+ and CD8+ T cells have a clearly demonstrated capacity to kill cells infected with HIV. But that response only arises some days, weeks and even months after a person has been exposed to HIV and the virus has integrated itself into cellular DNA, establishing lifelong infection. The adaptive immune response can only contain an established infection, it cannot prevent that infection from occurring at its onset.

The innate immune system is the first line of defense against infection. It attacks at the initial exposure to a pathogen, and can prevent the establishment of infection—and HIV is no exception. But there are a number of reasons why it has proved difficult to identify components of the innate immune response that can neutralize the deadly virus. HIV transmission is not very efficient. Exposed persons may avoid infection for a variety of mechanical (barrier) and biological reasons, such as the virus's failure to penetrate to the surface of mucosal tissue or dendritic cell difficulties in latching onto the virus to carry it to a lymph node. So it is challenging to conclusively identify the contribution of a specific innate immune response that can prevent an initial infection. Over the years, it has become clear that there are factors other than CD4+ and CD8+ T cells that help to control the virus in at least a portion of those infected with HIV.

Researchers have identified several antibodies that can neutralize the virus.

More here.