Background
Early ART and virological suppression may impact on evolving antibody responses to HIV-infection. We evaluated frequency and predictors of seronegativity in infants starting early ART.
Methods
HIV-antibody results were compared between two of three arms of the Children with HIV Early Antiretroviral Therapy (CHER) trial: HIV-infected infants aged <12 weeks with CD4 ≥25% randomised to early-limited ART for 96 weeks (ART-96W) or deferred ART until clinical/immunological progression (ART-Def). HIV-infection was diagnosed by DNA PCR and RNA >1000 copies/ml. ART started at median age 7 and 23 weeks respectively. Antibody was measured from all available stored samples, ART-96W (n=109) and ART-Def (n=75), at trial week 84 (median age 92 (IQR 90.6–93.4) weeks) using 3 assays: 4th generation EIA HIV-antigen/antibody combination; HIV-1/2 rapid-antibody test and quantitative anti-gp120 IgG ELISA.
Findings
More ART-96W were seronegative than ART-Def by EIA (46% versus 11%, p<0.0001) and rapid-antibody test (53% versus 14%, p<0.0001). Anti-gp120 IgG was lower in ART-96W versus ART-Def (median 230 (133–13,129) versus 6,870 (IQR 1,706–53,645)μg/μl). Starting ART between 12-24 versus 0-12 weeks increased odds of seropositivity 13.7-fold (95%CI 3.1-60.2). All children starting ART aged >24 weeks were seropositive. Cumulative viral load to week 84 correlated with anti-gp120 IgG levels (coefficient=0.54, p<0.0001) and increased odds of seropositivity OR 1.58 (95%CI 1.1-2.3) adjusted for ART-initiation age.
Interpretation
Almost half children starting ART before aged 12 weeks were HIV-seronegative by at aged ∼2 years. HIV-antibody tests cannot be used to re-confirm HIV-diagnosis in children starting early-ART. Long-term consequences of seronegativity need further study.
Funding
Wellcome Trust, Medical Research Council, National Institutes of Health.