Genetic characterization of measles virus circulating in Jharkhand

BACKGROUND: Measles virus (MeV) transmission pathways can be traced via molecular surveillance based on the N-450 region of the Nucleocapsid gene of the virus. Genetic characterization of MeV can identify the circulating genotypes in a given area and provide insights into vaccine efficacy on them. OBJECTIVE: India is a vast country where molecular surveillance data on circulating MeV from all states can help gauge vaccination coverage in the elimination settings of measles. The aim of the study was genetic characterization of circulating MeV in Jharkhand and evaluate the effectiveness of vaccination drives. STUDY DESIGN: Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was employed to detect MeV RNA in samples used for molecular testing. The positive RT-PCR products were sequenced, phylogenetic analysis performed, and submitted in the MeaNS2 (Measles Nucleotide Surveillance2) database. RESULTS: 113 of the 788 molecular samples from 788 cases tested positive by RT-PCR, and sequencing was carried out on these samples. 82 samples yielded good sequences on which phylogenetic analysis was done. All sequences clustered around MANCHES.UNK94 of D8 genotype. 13 Distinct Sequence Identifier (DSId) within D8 genotype identified. The maximum cases were less than 5 years of age. No vaccine strains were identified. CONCLUSIONS: Molecular surveillance data based on virus detection and genotyping helped to identify the circulating genotype of MeV, which is the D8 genotype in Jharkhand. Many DSIds indicate lineages of the current D8 genotype, which can be controlled with existing vaccines. Immunity gaps need to be addressed by stringent vaccination coverage.