LAUSR

OBJECTIVE(S) To elucidate relationships in antiretroviral (ARV) resistance between HIV-1 infected mother-infant pairs by defining the resistance profiles in the mothers and infants and quantifying drug resistance prevalence in the pairs post-Option B+ implementation. DESIGN Collection of dried blood spots (DBS) from mother-infant pairs during routine HIV-1 screens in Lusaka, Zambia from 2015 to 2018. METHODS DNA was extracted from the DBS, the HIV-1 pol region was amplified, and the purified proviral DNA was sequenced using Sanger sequencing. Drug resistance mutations (DRM) were identified in sequenced DNA using the Stanford HIVdb (https://hivdb.stanford.edu/). RESULTS DRM were detected in 45% (44/97) of samples, and these samples were found to harbor resistance to at least two ARVs. The prevalence of non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance was significantly higher than that of other ARV classes. DRM were detected disproportionately in infants (67%; 33/49) compared to mothers (23%; 11/48), but the magnitude of resistance did not differ when resistance was detected. The disparity in drug resistance profiles was reinforced in pairwise comparison of resistance profiles in mother-infant pairs. CONCLUSIONS While Option B+ is effective in reducing mother to child transmission (MTCT), in cases where this regimen fails, high level NNRTI resistance is frequently detected in infants. This underscores the importance of pre-treatment drug resistance screening in both mothers and infants and emphasizes the necessary change to protease inhibitor (PI)-based and integrase inhibitor (INI)-based regimens for treatment of HIV-1 infected infants and mothers.