The Journal of infectious diseases 2017 10 17() doi 10.1093/infdis/jix543
Data on how RSV genotypes influence disease severity and host immune responses is limited. We characterized the genetic variability of RSV during five seasons, and evaluated the role of RSV subtypes, genotypes and viral loads on disease severity and host transcriptional profiles.
Prospective, observational study including a convenience sample of healthy infants hospitalized with RSV bronchiolitis. Nasopharyngeal samples for viral load quantitation, typing and genotyping, and blood samples for transcriptome analyses were obtained within 24h of hospitalization. Multivariate models were constructed to identify virologic and clinical variables predictive of clinical outcomes.
From 3/2004 to 4/2011, we enrolled 253 infants (57% males; median age 2.1 [1.1-4.0] moths). RSV-A infections predominated over RSV-B (69% vs. 31%; p<0.001) and showed greater genotype variability. RSV A/GA2, A/GA5 and RSV B/BA were the most common genotypes identified. Compared to GA2 or BA, infants with GA5 infections had higher viral loads (p<0.01). Adjusted for other covariates, GA5 infections were also associated with longer hospital stay, and with less activation of interferon and increased overexpression of neutrophil genes. Conclusions
RSV-A infections were more frequent than RSV B, and displayed greater variability. GA5 infections were associated with enhanced disease severity and distinct host immune responses.