Evaluation of postpartum HIV superinfection and mother-to-child transmission

Abstract

Objective: This study examined HIV superinfection in HIV-infected women postpartum, and its association with mother-to-child transmission (MTCT).

Design: Plasma samples were obtained from HIV-infected women who transmitted HIV to their infants after 6 weeks of age (transmitters, n = 91) and HIV-infected women who did not transmit HIV to their infants (nontransmitters, n = 91). These women were originally enrolled in a randomized trial for prevention of MTCT of HIV in Malawi (Post-Exposure Prophylaxis of Infants trial in Malawi).

Methods: Two HIV genomic regions (p24 and gp41) were analyzed by next-generation sequencing for HIV superinfection. HIV superinfection was established if the follow-up sample contained a new, phylogenetically distinct viral population. HIV superinfection and transmission risk were examined by multiple logistic regression, adjusted for Post-Exposure Prophylaxis of Infants study arm, baseline viral load, baseline CD4 cell count, time to resumption of sex, and breastfeeding duration.

Results: Transmitters had lower baseline CD4 cell counts (P = 0.001) and higher viral loads (P < 0.0001) compared with nontransmitters. There were five cases of superinfection among transmitters (rate of superinfection = 4.7/100 person-years) compared with five cases among the nontransmitters (rate of superinfection = 4.4/100 person-years; P = 0.78). HIV superinfection was not associated with increased risk of postnatal MTCT of HIV after controlling for maternal age, baseline viral load, and CD4 cell count (adjusted odds ratio = 2.32, P = 0.30). Longer breastfeeding duration was independently associated with a lower risk of HIV superinfection after controlling for study arm and baseline viral load (P = 0.05).

Conclusion: There was a significant level of HIV superinfection in women postpartum, but this was not associated with an increased risk of MTCT via breastfeeding.

Trial registration: ClinicalTrials.gov NCT00115648.

Figures

Figure 1

Clinical and trial data by woman for the ten cases of HIV superinfection were identified. Five cases from the transmitting women (Cases #1-5) and five cases from the non-transmitters (Cases #6-10) are shown (corresponding phylogenetic trees are shown in supplemental figure 1). Grey arrow: indicates duration of breastfeeding based on self-report; Black arrow: indicates the visit where infant was diagnosed with HIV; Red arrow: indicates the visit HIV superinfection was detected; Blue arrow: indicates the visit the woman reported resumption of sexual activity. Abbreviations: Inf: Infant; SI: superinfection; SR: sex resumed; wk: weeks; mo: months; CD4: CD4 cell count (expressed as cells/mm3); n/a: not applicable; VL: HIV viral load (expressed as log10copies/mL).