Molecular-genetic characterization of human parvovirus B19 prevalent in Kerala State, India

Human parvo B19V virus from India's southern part, a geographically distinct location with no reports of B19V genomes, we have screened for B19V in 456 suspected cases using VP1/2 surface marker genes, and its characteristics were studied in detail. Amongst 456 clinically suspected B19V samples, 7.2% (33/456) were found positive by nested PCR (nPCR) and subsequently validated by real-time PCR. The complete VP1/2 gene assembly from the South Indian strain showed three novel mutations (T122A, V128I, I283V), which might significantly impact the stability and virulence of the B19V virus. These mutations might be crucial for its adaptive evolution strategies facilitating the spread of the virus. One of the novel mutations, I283V in the South Indian B19 isolate, was seen closer to its known antigenic determinant sites. This might help the virus evade host neutralizing antibodies. In maximum likelihood phylogeny of VP1/2 sequences, the south Indian B19V strain forms a separate clade closer to the existing genotype two strains circulating worldwide. Our study contributes to a better understanding of the human parvovirus's genetic and evolutionary characteristics in south Indian. Also, it highlights the possibility that a positive selection pressure acting on VP1/2 could increase the survival and replication capabilities of the virus.