Clinical Course and Molecular Characterization of Human Bocavirus Associated with Acute Lower Respiratory Tract Infections in a Tertiary Care Hospital in Northern India.

Respiratory samples from 139 hospitalized children were screened for the human bocavirus (HBoV) genome. Positive samples were sequenced for the partial VP1/VP2 gene followed by molecular and phylogenetic analyses. HBoV positivity was noted in 7.2% (10/139) of patients. All HBoV-positive children presented with fever, cough, and respiratory distress (90%, 9/10). Three children developed multisystemic viral illness, with one fatality. Eight children required intensive care management and five required mechanical ventilation. The nucleotide percent identity of the partial VP1/VP2 gene in the HBoV study strains ranged from 97.52% to 99.67%. Non-synonymous mutations in the VP1 protein were T591S (n = 8) and Y517S (n = 1) in the HBoV St1 strain and N475S (n = 8) and S591T (n = 2) in the HBoV St2 strain. One strain showed A556P, H556P, I561S, and M562R non-synonymous mutations. All the study strains belonged to the HBoV1 type. Seven HBoV strains belonged to the same lineage, and three belonged to another lineage. For evolutionary dynamics, GTR+I substitution model with uncorrelated relaxed lognormal clock and Bayesian Skyline tree prior showed 9.0 × 10-4 (95% highest probability density interval: 3.1 × 10-6, 2.1 × 10-3) nucleotide substitutions per site per year. Clinical suspicion and virological screening are necessary to identify HBoV infections in children.