SAN FRANCISCO  Government scientists have discovered a new way that H.I.V. attacks human cells, an advance that could provide fresh avenues for the development of additional therapies to stop AIDS, they reported on Sunday.

The discovery is the identification of a new human receptor for H.I.V. The receptor helps guide the virus to the gut after it gains entry to the body, where it begins its relentless attack on the immune system.

The findings were reported online Sunday in the journal Nature Immunology by a team headed by Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases.

For years, scientists have known that H.I.V. rapidly invades the lymph nodes and lymph tissues that are abundant throughout the gut, or intestines. The gut becomes the prime site for replication of H.I.V., and the virus then goes on to deplete the lymph tissue of the key CD4 H.I.V.-fighting immune cells.