Genetic diversity of saglin in Anopheles stephensi: insights from Iranian isolates for malaria transmission-blocking vaccine development

Malaria, a life-threatening disease transmitted by infected mosquitoes, remains a major global health challenge. Despite significant progress in reducing cases and mortality in some regions, endemic areas continue to face high transmission rates, highlighting the limitations of current control measures. In response, the malERA initiative (2011) proposed updated strategies based on scientific insights, emphasizing the development of transmission-blocking vaccines (TBVs) for countries in the final phases of elimination. Among these, mosquito-based vaccines have gained attention. Given the critical role of Anopheles stephensi in malaria transmission in the Eastern Mediterranean Region, this study conducted a population genetic analysis of the saglin gene in An. stephensi . A total of 30 An. stephensi mosquitoes were collected from three malaria-endemic regions in Iran. DNA was extracted, and the saglin gene was amplified and analyzed for genetic diversity using DnaSP 6.0 software. B-cell and T-cell epitopes were predicted and the interaction of SAGLIN-derived peptides with MHC-II molecules common in Iran was evaluated. Nine haplotypes and five synonymous SNPs were identified among the 30 An. stephensi isolates. All populations exhibited negative Tajima’s D and dN-dS values. Predicted linear and conformational B-cell epitopes were mainly located in conserved regions of the internal segments of the SAGLIN protein. Additionally, a strong binding affinity was observed between prevalent Iranian MHC-II alleles and SAGLIN-derived peptides. The genetic analysis indicated that SAGLIN is highly conserved at the amino acid level, with no evidence of positive selection. The observed compatibility with common MHC-II alleles suggests the potential of SAGLIN to elicit effective immune responses. Therefore, SAGLIN represents a promising candidate for the development of a regional subunit transmission-blocking vaccine against malaria.