Human immunodeficiency virus type 1 drug resistance among patients failing second-line antiretroviral treatment in Butha-Buthe and Mokhotlong, Lesotho

Abstract

Background: To date, there is no cure for HIV. However, antiretroviral treatment (ART) is used to control the replication of HIV and many people living with HIV take ART. Unfortunately, over time, some patients develop drug resistance which is becoming a major public threat limiting future treatment options for people living with HIV. HIV-1 drug resistance is defined as the ability of HIV-1 to mutate and reproduce itself in the presence of ARV drugs. This occurs as a result of: (a) poor adherence to treatment; (b) inadequate potency of ARVs; (c) suboptimal drug levels and (d) pre-existing resistance. There are two types of resistance-associated mutations (RAMs) namely acquired and transmitted. When an individual is infected with HIV-1 resistant strain, it may become the dominant strain for further transmission leading to increasing number of antiretroviral-naive patients and reducing their therapeutic effectiveness. HIV drug resistance testing is a test used to detect the presence of RAMs to HIV type 1 (HIV-1). Currently patients are switched empirically in the country. Therefore, it is crucially important to understand the HIV drug resistance pattern in order to find ways how to limit the occurrence. This will helpful in the clinical decision making and selection of regimens upon treatment failure. Objective: The objective of the study was to access the prevalence and patterns of HIV resistance-associated mutations in patients with an unsuppressed viral load when taking second-line ART in Butha-Buthe and Mokhotlong districts, Lesotho. Methods: In a retrospective study, we used convenience sampling and sequenced all eligible (patients on second line ART with a viral load ≥ 1000 copies/mL) stored leftover plasma samples taken between January 2016 and October 2020. The study was conducted at Seboche Hospital Laboratory which served all health facilities (hospitals and clinics) in the northern region of Lesotho. During testing, RNA extraction was done manually using the Purelink Viral/DNA kit. PCR amplification and sequencing of the protease (PR) and reverse transcriptase (RT) region was done using the Amplification and Sequencing module kits developed by Thermo Fisher Scientific. Consensus sequences were derived, aligned, and analysed using the web-based Recall software. The Stanford HIV Drug Resistance Database was used to interpret the presence or absence of drug resistant mutants. Results and discussion: Out of 55 patients’ samples, 30 samples were successfully amplified and sequenced. The median age was 41 years (IQR: 30 to 49) and the majority (62%) of participants were female. The median duration on a second-line regimen at the time of phlebotomy was 1.9 years (IQR: 0.5 to 3.0). The majority of patients (94%) were taking ritonavir-boosted lopinavir-based ART. Major RAMs were observed in 62% of participants; one patient had major RAMs in the PR while 18 had RAMs in the RT region. All participants had HIV-1 subtype C. The most frequent mutations conferring resistance to nucleoside reverse transcriptase inhibitors were M184V (31%) and K70R/E (16%), while the most frequent mutations conferring resistance to non-nucleoside reverse transcriptase inhibitors were K103N (38%), P225H (19%) and G190A (19%). The observed PR mutations from one sample were M46I, I54L and V82L. Only 10 (31%) patients had RAMs which conferred resistance to their second-line regimen. Though RAMs were detected, the majority of patients had three active drugs in their second-line regimen and many observed mutations likely conferred resistance to their previous regimens. Conclusion: Though 62% of patients had RAMs, only 31% had RAMs conferring resistance to their second-line regimen during the first 2 years after switch to second-line ART, indicating that adherence plays a major role in second-line treatment failure. These RAMs reflect the reality of HIV care in resource-limited settings such as Lesotho. Adherence should be strengthened among people with treatment failure while taking second-line ART in order to avoid development of resistance mutations.