Study of drug resistance mutations in HIV-positive individuals using Sanger sequencing analysis

Aim: This study aims to investigate the demographic characteristics, viral genetic diversity, drug resistance analysis, and immunological markers of 132 individuals diagnosed with HIV in Şanlıurfa. Material and Method: Through 2020 to 2024, Sanger sequencing was performed on samples from 132 untreated HIV patients in Şanlıurfa using the ABI 3500xl Genetic Analyzer (Applied Biosystems, USA). CD4 T lymphocyte counts were determined using the BD FACSLyric flow cytometry system, and the HIV RNA levels were analyzed using the ELITe BeGenius device. The demographic information of the patients was obtained retrospectively from the hospital information system. Results: In terms of possible HIV transmission routes, the most common route was reported as heterosexual transmission at 41.7%, followed by other/unknown at 34.1% and homosexual (MSM) transmission at 24.2%. The median HIV RNA level of the patients was 62,059 copies/mL (1-17,400,000), the median CD4 cell count was 354 cells/mm³ (9-1137), and the median CD4/CD8 ratio was 0.30 (0.01-0.91). In the distribution of HIV subtypes, subtype B was detected in 70.5% and nonB subtypes in 29.5%. Among non-B subtypes, the most common types were CRF56_cpx at 35.8%, subtype A at 15.3%, CRF29_BF subtype at 10.3%, and subtype C at 7.6%. Drug resistance was present in 40.9% of the patients (n: 54), while 59.1% (n: 78) had no drug resistance. When examining the resistance distribution according to ARV groups, 33.3% (n: 44) were found to be resistant to NNRTI, 5.3% (n: 7) to NRTI, and 2.3% (n: 3) to PI. At least one mutation was observed in 64.4% of the patients (n: 85). Among the most frequently detected mutations, S68G (NRTI) was found in 65.9%, E138A (NNRTI) in 51.8%, M41L (NRTI) in 8.2%, T215S (NRTI) in 8.2%, and V106I (NNRTI) in 4.7%. A negative weakly significant correlation was found between HIV RNA level and CD4 T lymphocyte count. The median HIV RNA levels were found to be significantly higher in the other/unknown transmission route group compared to the heterosexual and homosexual transmission routes (p<0.05). A significant relationship was found between possible transmission route and gender (p<0.001). The difference originates from the group with heterosexual transmission. A significantly higher number of mutations were detected in individuals with subtype B (p<0.05). No significant difference was found in HIV RNA levels, CD4 cell counts, and CD4/CD8 medians regarding the presence/absence of mutations and the presence/absence of drug resistance (p>0.05). Conclusion: The findings provide important information about the local epidemiological status of HIV infection and emphasize the importance of conducting genotypic resistance tests in every patient diagnosed with HIV infection. Due to the genetic diversity of HIV, primary drug resistance should be monitored more carefully in epidemiological studies which helps to prevent the spread of resistant strains in the community.