Drug resistance mutations in newly diagnosed HIV-infected infants and in children and adolescents with virological failure on ART
Introduction and aim: South Africa has never experienced an epidemic of the same extent and magnitude as the one with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS).The roll out of antiretroviral therapy (ART) and other interventions, such as prevention of mother to child transmission (PMTCT), has greatly reduced the incidence of new HIV infections among children. However, early initiation of ART among children has increased their overall exposure to antiretrovirals (ARVs), resulting in an increased prevalence of acquired drug resistance (ADR) on treatment. Presence of drug resistant virus further complicates clinical management of HIV infection, resulting in fewer present and future treatment options. Therefore, drug resistance testing has been recommended in selecting appropriate treatment regimens among children and adolescents diagnosed with virological failure. The aim of the current study was to determine and characterise drug resistance mutations in newly diagnosed HIV-infected children and in children and adolescents with virological failure on ART. Methods: To detect drug resistance mutations, the present study developed and validated a Sanger sequencing assay using dried blood spot (DBS) samples. The Sanger assay was used to perform HIV drug resistance testing on DBS samples testing positive on the early infant diagnosis (EID) platform. Lastly, a retrospective analysis was performed of resistance data from samples of children and adolescents submitted to the routine diagnostic laboratory. Results: A high level of concordance was found among major mutations detected using the Sanger DBS and plasma assays. Since all the discordant mutations were either minor or existed as mixtures, the interpretation of resistance profiles was found to be identical. The DBS assay was then used to detect pre-treatment drug resistance (PDR) among samples from children on the EID platform. Overall, PDR was detected among 73% of the children, with the majority of the children showing resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) (72%). Dual class resistance was most prevalent to NNRTIs and NRTIs (11% [33/308]), followed by NNRTIs + protease inhibitors (PIs) (0.6% [2/308]). Triple class resistance (NNRTI + NRTI + PI) was very rare and was only detected in two children. Protease resistance was very rare among the children and none of the children displayed high-level resistance against any PI. Results from children (0 to 9 years) and adolescents (10 to 19 years) with virological failure while on ART indicated that most of the children were resistant to NRTIs (86% [79/92]), followed by NNRTIs (75% [69/92]) and PIs (28% [26/92]). Among adolescents, prevalence of resistance to NNRTIs (87% [146/167]) was the highest, followed by NRTIs (66% [111/167]) and PIs (30% [51/167]). Dual class resistance to NRTIs + NNRTIs was the most common among both children (44% [41/92]) and adolescents (38%, [63/167]). Triple class resistance (NNRTI+NRTI+PI) was detected in 18% of children (17/92) and 19% of adolescents (32/167). Conclusion: The prevalence of infants, children and adolescents experiencing treatment failure due to the presence of transmitted, acquired and PDR is increasing. While the implementation of virological monitoring and genotypic testing play an essential role in identifying and managing drug resistance among children and adolescents experiencing treatment failure, these services are limited in many developing countries. The current study supports the implementation of HIV drug resistance testing for national surveys and optimal clinical management of HIV-infected children and adolescents.