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. 2023 Oct;87(4):305-314.
doi: 10.1016/j.jinf.2023.07.008. Epub 2023 Jul 24.

Genetic diversity and its impact on disease severity in respiratory syncytial virus subtype-A and -B bronchiolitis before and after pandemic restrictions in Rome

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Free article

Genetic diversity and its impact on disease severity in respiratory syncytial virus subtype-A and -B bronchiolitis before and after pandemic restrictions in Rome

A Pierangeli et al. J Infect. 2023 Oct.
Free article

Abstract

Objectives: To scrutinize whether the high circulation of respiratory syncytial virus (RSV) observed in 2021-2022 and 2022-2023 was due to viral diversity, we characterized RSV-A and -B strains causing bronchiolitis in Rome, before and after the COVID-19 pandemic.

Methods: RSV-positive samples, prospectively collected from infants hospitalized for bronchiolitis from 2017-2018 to 2022-2023, were sequenced in the G gene; phylogenetic results and amino acid substitutions were analyzed. Subtype-specific data were compared among seasons.

Results: Predominance of RSV-A and -B alternated in the pre-pandemic seasons; RSV-A dominated in 2021-2022 whereas RSV-B was predominant in 2022-2023. RSV-A sequences were ON1 genotype but quite distant from the ancestor; two divergent clades included sequences from pre- and post-pandemic seasons. Nearly all RSV-B were BA10 genotype; a divergent clade included only strains from 2021-2022 to 2022-2023. RSV-A cases had lower need of O2 therapy and of intensive care during 2021-2022 with respect to all other seasons. RSV-B infected infants were more frequently admitted to intensive care units and needed O2 in 2022-2023.

Conclusions: The intense RSV peak in 2021-2022, driven by RSV-A phylogenetically related to pre-pandemic strains is attributable to the immune debt created by pandemic restrictions. The RSV-B genetic divergence observed in post-pandemic strains may have increased the RSV-B specific immune debt, being a possible contributor to bronchiolitis severity in 2022-2023.

Keywords: Bronchiolitis severity; Genetic variability; Genotypes; Post-pandemic strains; Respiratory syncytial virus.

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Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: GUIDO ANTONELLI reports financial support was provided by EU funding within the NextGeneration EU-MUR PNRR. ANNA TERESA PALAMARA reports financial support was provided by Italian Ministry of Health.

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