Circulation of Mumps virus genotype G in Pakistan during 2023 outbreak

Aim: Despite recurring mumps outbreaks in Pakistan, the virus's genomic diversity remains unavailable. This study explores the mumps genomic diversity in the 2023 Islamabad outbreak. Methods: During January and February 2023, 32 buccal/throat swabs were collected from suspected mumps cases. 15 tested mumps virus (MuV)-positive via RT-PCR. Positive samples underwent partial SH gene sequencing; a subset (n = 10) was whole-genome sequenced using Illumina MiSeq. Results: Phylogenetic analysis identified genotype-G, sharing 95.57-98.73% homology with Japanese/Canadian isolates. Whole-genome-sequencing (n = 2) confirmed genotype-G, 99% similar to Sheffield/Iowa strain. HN region displayed 95.01-95.36% identity with Jeryl Lynn, with genotype G-specific mutations, except T265I. Conclusion: This is the first report of partial and whole-genome sequencing of MuV from Pakistan, highlighting the necessity for genomic surveillance and vaccine integration. This study investigated the different types of mumps virus (MuV) in Islamabad during the 2023 outbreak. Out of 32 people thought to have mumps, 15 were confirmed by lab tests. We found that these 15 people had been infected by the same type of MuV, similar to those that have been investigated in Japan and Canada. Two people had also been infected by a type of MuV that was responsible for an outbreak in the USA in 2006. This is the first study of its kind in Pakistan. It shows how important it is to monitor MuV and to include the MuV vaccine in the national program. This could help to better control mumps infections in the future.