Reactivity of routine HIV antibody tests in children who initiated antiretroviral therapy in early infancy as part of the Children with HIV Early Antiretroviral Therapy (CHER) trial: a retrospective analysis

Abstract

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.

Prevalence and outcomes of HIV‐1 diagnostic challenges during universal birth testing – an urban South African observational cohort

“…Although the association between ART and indeterminate HIV-1 PCR results has been highlighted, and recommendations made regarding the management of such infants, further research is required to ensure timely definitive diagnosis and successful linkage to care [18,19]. Waning antibody levels and seroreversion following early ART initiation are additional phenomena that make later diagnostic confirmation difficult [20][21][22]. In contrast to the possibility of loss of detectability, there is also concern that on account of the dramatic reduction in motherto-child transmission in South Africa there will necessarily be a drop in the positive predictive value of all infant diagnostic testing methodologies, thereby increasing the risk of treating uninfected infants [23][24][25].…”

Lessons in diagnostic virology: expected and unexpected sources of error

“…Similar to acutely treated adults HIV antibody assays can be false negative in early treated children, likely due to a lack of antigenic stimulation of the developing humoral immune system. This could pose diagnostic challenges later on and even result in mothers falsely thinking their children have been cured . HIV rapid serological assays may also perform more poorly in field settings than expected from laboratory based evaluations, which could be due to various factors including operator performance or population characteristics …”

HIV misdiagnosis in paediatrics: unpacking the complexity

“…A number of studies have documented that this phenomenon is more likely when infants are started on ART in the first months of life [17,18], but false negatives may also occur when ART is started later, particularly when oral RDTs are used. This has the potential to generate confusion among providers and the family and may present the dilemma of interrupting ART to see if the child is truly infected.…”