Clinical course and molecular characterization of human Bocavirus associated with acute lower respiratory tract infections in tertiary care hospital of north India.

Respiratory samples from 139 hospitalized children were screened for the Human Bocavirus (HBoV) genome. Positive samples were sequenced for partial VP1/VP2 gene followed by molecular and phylogenetic analyses. HBoV positivity was noted in 7.2% (10/139) patients. All HBoV positive children presented with fever followed by cough and respiratory distress (90%; 9/10). Three children developed multisystemic viral illness with one fatality. Eight children required intensive care management and mechanical ventilation required for 5 children. Nucleotide percent identity of partial VP1/VP2 gene of HBoV study strains were ranging from 97.52% to 99.67%. Non-synonymous amino acid mutations in VP1 protein revealed T591S (n=8) and Y517S (n=1) mutations in comparison to HBoVSt1 strain where N475S (n=8) and S591T (n=2) mutations in comparison to HBoVSt2 strain. One study strain showed A556P, H556P, I561S and M562R non-synonymous mutations. All the study strains belong to HBoV1 type. Seven HBoV strains belong to same lineage and three belong to another lineage. For evolutionary dynamics, GTR+I substitution model with uncorrelated relaxed lognormal clock and Bayesian Skyline tree prior showed 9.0 x 10-4 [95% HPD interval: 3.1 x10-6, 2.1 x 10-3] nucleotide substitutions/site/year. The clinical suspicion and virological screening is necessary for identification HBoV in children.