U. Bredbergraden et al., EARLY DIAGNOSIS OF HIV-1 INFECTION IN INFANTS IN DAR-ES-SALAAM, TANZANIA, Clinical and diagnostic virology, 4(2), 1995, pp. 163-173
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.