Newly Discovered Molecule May Facilitate HIV Transmission

Researchers from the Netherlands and New York have discovered a molecule on the "fingerlike" dendritic cells, located just beneath the skin and "moist mucosal tissue" of the vagina, urethra and penis, that shuttles HIV from the point of entry to the immune system, the New York Times reports. The molecules, called DC-SIGN, short for dendritic-cell specific, icam-grabbing nonintegrin, "lie in wait, ready to greet and capture invading microbes" like HIV, then carry the virus to the lymph nodes where they can be attacked by CD4+ T cells and other immune cells. However, as HIV "attacks and replicates" in CD4+ cells, the DC-SIGN molecules serve as HIV's "navigational guide" in the human body. In addition, researchers have discovered that DC-SIGN molecules allow HIV to survive for four days in the body by binding to the virus; otherwise the virus "would die much sooner." This property of DC-SIGN may explain why it only takes a small amount of HIV to "enter, survive and then amplify in large amounts to damage the immune system and create AIDS," according to Dr. Yvette van Kooyk of the Netherlands' University of Nijmegen. Van Kooyk's team partnered with another team headed by Dr. Dan Littman of New York University. The New York Times reports that DC-SIGN may "offer potential practical applications": the development of a chemical that could serve as a microbicide that blocks the molecule, or the development of a vaccine that would target DC-SIGN (Altman, New York Times, 2/9).