CRF08_BC subtype is more prone to ART failure and new-generation NNRTI-resistance under long-term first-line ART.

Objective: To investigate the characteristics of drug resistance mutations (DRMs) and their contextual influence on drug susceptibility in CRF07_BC and CRF_08BC subtypes.

Methods: Patients with virological failure were genotyped using phylogenetic analysis. DRMs and susceptibility to antiretroviral drugs were analysed using the Stanford University HIV Drug Resistance Database.

Results: Six HIV subtypes were identified among 1296 successfully amplified sequences, with the CRF07_BC subtype prevailing at a rate of 91.7%, followed by CRF08_BC. Overall, the CRF07_BC and CRF08_BC subtypes were similar in the distribution and frequency of DRMs, the most common DRMs were K103N and M184V. However, among patients with antiretroviral therapy duration of ≥3 y who developed resistance, CRF08_BC exhibited a higher mutation frequency at sites 184, 138, 221, and 188 (Chi-square test, P < 0.05), and compared with CRF07_BC, patients with CRF08_BC had higher prevalence of abacavir, emtricitabine, lamivudine, doravirine, etravirine, and rilpivirine resistance. Moreover, there was an increased prevalence of cross-resistance between efavirenz/nevirapine and new-generation NNRTIs in patients with CRF08_BC; doravirine (r = 1.0), rilpivirine (r = 0.93), and etravirine (r = 0.86) resistance highly correlated with efavirenz/nevirapine.

Conclusions: The present study provides valuable insights into the profile of DRMs and resistance patterns in patients with CRF07_BC and CRF08_BC experiencing treatment failure in Butuo. These findings have the potential to contribute to future strategies for HIV control and treatment.