Inadequate Host Immune System Can Lead to Seronegative HIV Infection

Seronegative HIV-1 infection appears to be caused by an inability of the host to form HIV-1-specific antibodies, rather than to a highly virulent strain of the virus as has been suggested in the past, investigators in Portugal report.

Dr. Ana R. Cardoso, at Hospital Nossa Senhora da Craca in Tomar, and associates treated a woman who presented in 2001 with fever, malaise, anorexia and oral thrush. Serological testing in 1997 and 1999 had yielded negative results, as were those performed in October, November and December.

The diagnosis was made in December based on the detection of p24 antigen and HIV-1 RNA in plasma, the authors report in the April 30th issue of AIDS. Her current sexual partner was tested and found to be seropositive, even though he was asymptomatic.

Dr. Cardoso's group sequenced regions of the env and gag genes from both individuals.

Both were infected with HIV-1 subsubtype A2. That from the man had more sequence divergence, whereas that from the woman had very low genetic diversity, "consistent with a recent infection and the absence of immunologic pressure imposed on the viruses."

"Further studies are needed to permit the identification of the immunological defect causing seronegative HIV-1 infection, because this may have important implications for diagnosis, the prevention of viral transmission and vaccination," they conclude.

05/26/04

AIDS 2004;18:1071-1073.