The importance of heteroresistance and efflux pumps in bedaquiline-resistant Mycobacterium tuberculosis isolates from Iran.

BACKGROUND: Tuberculosis (TB) continues to pose a threat to communities worldwide and remains a significant public health issue in several countries. We assessed the role of heteroresistance and efflux pumps in bedaquiline (BDQ)-resistant Mycobacterium tuberculosis isolates. METHODS: Nineteen clinical isolates were included in the study, of which fifteen isolates were classified as MDR or XDR, while four isolates were fully susceptible. To evaluate BDQ heteroresistance, the Microplate Alamar Blue Assay (MABA) method was employed. For screening mixed infections, MIRU-VNTR was performed on clinical isolates. Mutations in the atpE and Rv0678 genes were determined based on next-generation sequencing data. Additionally, real-time PCR was applied to assess the expression of efflux pump genes in the absence and presence of verapamil (VP). RESULTS: All 15 drug-resistant isolates displayed resistance to BDQ. Among the 19 total isolates, 21.05% (4/19) exhibited a heteroresistance pattern to BDQ. None of the isolates carried a mutation of the atpE and Rv0678 genes associated with BDQ resistance. Regarding the MIRU-VNTR analysis, most isolates (94.73%) showed the Beijing genotype. Fifteen (78.9%) isolates showed a significant reduction in BDQ MIC after VP treatment. The efflux pump genes of Rv0676c, Rv1258c, Rv1410c, Rv1634, Rv1819, Rv2459, Rv2846, and Rv3065 were overexpressed in the presence of BDQ. CONCLUSIONS: Our results clearly demonstrated the crucial role of heteroresistance and efflux pumps in BDQ resistance. Additionally, we established a direct link between the Rv0676c gene and BDQ resistance. The inclusion of VP significantly reduced the MIC of BDQ in both drug-susceptible and drug-resistant clinical isolates.

The impact of genetic variation in IL28B, IFNL4 and HLA genes on treatment responses against chronic hepatitis C virus infection.

Single nucleotide polymorphisms (SNPs) near the interleukin-28B (IL28B), interferon lambda 4 (IFNL4) and the human leukocyte antigen (HLA) gene are associated with treatment responses in patients with chronic hepatitis C (CHC) virus infection treated with pegylated interferon-α and ribavirin (pegIFN-α/RBV). We compared the role of IL28B SNPs (rs12979860, rs12980275, and rs8099917), IFNL4 ss469415590 and HLA rs4273729 with treatment outcomes in patients with CHC virus. A total of 520 Iranian patients with CHC infection were enrolled. SNPs in IL28B, IFNL4 ss469415590 and HLA rs4273729 were genotyped by PCR-restriction fragment length polymorphism, TaqMan® Real-Time PCR and direct sequence. Out of 520 CHC treatment-naive patients, 42.9% were infected with HCV-1a, 15.4% with HCV-1b, 9.8% with HCV-2, and 31.9% with HCV-3a. Rapid virologic response (RVR), complete early virologic response (cEVR), and sustained virologic response (SVR) were 53.3%, 73.8%, and 66.7%, respectively. Multivariate logistic regression analysis showed that IL28B rs12980275 and IFNL4 ss469415590 in all HCV genotypes were associated with RVR. In addition, IL28B rs12979860 and RVR in all HCV genotypes and IL28B rs12980275, IFNL4 ss469415590, and HLA rs4273729 in HCV subtypes 1a, 1b, and 3a correlated with cEVR. In patient's achieving-SVR, IL28B rs12980275, and RVR in all HCV genotypes and IL28B rs12979860, IFNL4 ss469415590, and HLA rs4273729 in HCV subtypes 1a, 1b, and 3a were the powerful predictor factors. As the first report of its kind published in Iran, we indicated that beside IL28B SNPs and HLA rs4273729, IFNL4 ss469415590 was a powerful predictor factor for RVR, cEVR and SVR. Genotyping these SNPs may be a helpful priority in the treatment of patients with HCV infection, especially in countries where access to triple or double therapy with a viral protease inhibitor is limited.