Scientists Find HIV Receptor That Takes Virus to the Gut
Dr. Anthony S. Fauci, reporting in the journal Nature Immunology, says he and a team have discovered a new HIV receptor that may help to develop additional therapies for the disease. The new receptor explains why HIV begins its attack on the immune system in the gut:
"Dr. Fauci, James Arthos, Claudia Cicala, Elena Martinelli and their colleagues showed that a molecule, integrin alpha-4 beta-7, which naturally directs immune cells to the gut, is also a receptor for H.I.V. A protein on the virus’s envelope, or outer shell, sticks to a molecule in the receptor that is linked specifically to the way CD4 cells home in on the gut, the researchers said. Binding of the virus to the integrin alpha-4 beta 7 molecule stimulates activation of another molecule, LFA-1, which plays a crucial role in the spread of the virus from one cell to another. The actions ultimately lead to destruction of lymph tissue, particularly in the gut. Several other receptor sites for H.I.V. are known. The most important is the CD4 molecule on certain immune cells; the molecule’s role as an H.I.V. receptor was identified in 1984. Two other important receptors, known as CCR5 and CXCR4, were identified in 1996. CCR5 is a normal component of human cells and acts as a doorway for the entry of H.I.V. People who lack it because of a genetic mutation rarely become infected even if they have been exposed to H.I.V. repeatedly. 'The work we did took nearly two years, and there’s little doubt that what we have found is a new receptor,' Dr. Fauci said in an interview after giving a lecture here, adding that 'we certainly have to learn a lot more about it.'"