EARLY DIAGNOSIS OF HIV-1 INFECTION IN INFANTS IN DAR-ES-SALAAM, TANZANIA

Objectives: To evaluate two simple methods, an immune complex dissocia tion (ICD) p24 antigen assay and an HIV-1-specific IgA antibody assay, for the early demonstration of HIV-1 infection in infants, using the polymerase chain reaction (PCR) as the reference method. Design and se tting: Group A: 143 HIV-1-seropositive and 134 -seronegative mothers a nd their infants were recruited at delivery at the main hospital in Da r es Salaam, Tanzania, Group B: 26 HIV-PCR-positive hospitalized child ren in Dar es Salaam, 3-15 months old and suspected of having an HIV-r elated illness. Methods: Blood samples were taken from mothers and inf ants in group A at intervals during the children's first 24 months and once from each of the children in group B. Peripheral blood mononucle ar cells were tested by nested PCR for viral DNA. Plasma samples were tested by the Coulter p24 antigen (ag) enzyme-linked immunosorbent ass ay (ELISA) after acid dissociation of p24 antigen-antibody complexes. All p24-ag-positive reactions were confirmed by neutralization. Viral specific IgA antibodies were demonstrated in plasma by a modified ELIS A.Results: One hundred and sixty-three of 174 samples from seropositiv e mothers were PCR-positive (sensitivity 93.7%) and 612 of 614 samples from seronegative mothers and children of seronegative mothers were P CR-negative (specificity 99.7%). Twenty-nine of 145 (20.0%) children b orn to seropositive mothers were positive by PCR when tested during th e first year of life, By use of both the p24 ag ELISA and the IgA anti body ELISA in combination, HIV-1 infection was detected in 9 of 17 (53 %) PCR-positive children 1-8 weeks old, in 15 of 18 (83%) PCR-positive children 9-26 weeks old and in 23 of 24 (96%) PCR-positive children 2 7-52 weeks old. The specificities of the p24 ag ELISA and the IgA ELIS A were 100%. Conclusions: The p24 ag assay and the IgA antibody ELISA, when used in combination, had a high sensitivity and specificity for detection of HIV-1 infection in infants, especially in those above the age of 6 months.