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A globally implemented unified phylogenetic classification for human respiratory syncytial virus (HRSV) below the subgroup level remains elusive. We formulated global consensus of HRSV classification on the basis of the challenges and limitations of our previous proposals and the future of genomic surveillance. From a high-quality curated dataset of 1,480 HRSV-A and 1,385 HRSV-B genomes submitted to GenBank and GISAID (https://www.gisaid.org) public sequence databases through March 2023, we categorized HRSV-A/B sequences into lineages based on phylogenetic clades and amino acid markers. We defined 24 lineages within HRSV-A and 16 within HRSV-B and provided guidelines for defining prospective lineages. Our classification demonstrated robustness in its applicability to both complete and partial genomes. We envision that this unified HRSV classification proposal will strengthen HRSV molecular epidemiology on a global scale.

We sequenced 54 respiratory syncytial virus (RSV) genomes collected during 2021-22 and 2022-23 outbreaks in Washington, USA, to determine the origin of increased RSV cases. Detected RSV strains have been spreading for >10 years, suggesting a role for diminished population immunity from low RSV exposure during the COVID-19 pandemic.

Introduction: Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infection (ALRTI) in pediatrics. Preterm infants are at a higher risk for complications. We aimed to describe and compare the clinical and epidemiological characteristics associated with ALRTI due to RSV in preterm and term infants and to establish the predictors of fatality among preterm infants., Methods: Prospective, cross-sectional study of patients admitted due to ALRTI in the 2000-2018 period. Viral diagnosis was done by indirect immunofluorescence or reverse transcription polymerase chain reaction in nasopharyngeal aspirates. Clinical and epidemiological characteristics were recorded. A multiple logistic regression model established the predictors of fatality among preterm infants., Results: A total of 16 018 ALRTI cases were included; 13 545 (84.6 %) were tested; 6047 (45 %) were positive; RSV was prevalent in 81.1 % (4907), with a seasonal epidemic pattern; 14 % (686) were preterm infants. Comorbidities, perinatal respiratory history, congenital heart disease, malnutrition, chronic respiratory disease, bronchopulmonary dysplasia, prior hospitalization due to ALRTI, and chronic neurological disease (p < 0.001) were more common among preterm infants; they required more intensive care and a longer length of stay, and had a higher fatality rate (p < 0.01). Congenital heart disease was an independent predictor of fatality due to RSV among preterm infants (OR: 3.67 [1.25-10.8], p = 0.01)., Conclusion: RSV showed an epidemic pattern and affected more preterm infants with certain comorbidities, with a higher morbidity and mortality, compared to term infants. RSV fatality among preterm infants was associated with congenital heart disease., Competing Interests: None, (Sociedad Argentina de Pediatría.)

Background: Human respiratory syncytial virus (RSV) is classified into antigenic subgroups A and B. Thirteen genotypes have been defined for RSV-A and 20 for RSV-B, without any consensus on genotype definition., Methods: We evaluated clustering of RSV sequences published in GenBank until February 2018 to define genotypes by using maximum likelihood and Bayesian phylogenetic analyses and average p-distances., Results: We compared the patterns of sequence clustering of complete genomes; the three surface glycoproteins genes (SH, G, and F, single and concatenated); the ectodomain and the 2nd hypervariable region of G gene. Although complete genome analysis achieved the best resolution, the F, G, and G-ectodomain phylogenies showed similar topologies with statistical support comparable to complete genome. Based on the widespread geographic representation and large number of available G-ectodomain sequences, this region was chosen as the minimum region suitable for RSV genotyping. A genotype was defined as a monophyletic cluster of sequences with high statistical support (≥80% bootstrap and ≥0.8 posterior probability), with an intragenotype p-distance ≤0.03 for both subgroups and an intergenotype p-distance ≥0.09 for RSV-A and ≥0.05 for RSV-B. In this work, the number of genotypes was reduced from 13 to three for RSV-A (GA1-GA3) and from 20 to seven for RSV-B (GB1-GB7). Within these, two additional levels of classification were defined: subgenotypes and lineages. Signature amino acid substitutions to complement this classification were also identified., Conclusions: We propose an objective protocol for RSV genotyping suitable for adoption as an international standard to support the global expansion of RSV molecular surveillance., (© 2020 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)

Respiratory syncytial virus (RSV) is the main viral cause of hospitalization due to acute lower respiratory tract infections in infants worldwide. Several vaccines against RSV are under research and development, which are about to be approved. We evaluated transmission patterns in different settings to determine age-specific vaccination targets from a viral perspective. We sequenced the G glycoprotein's ectodomain of a constant clinical sampling between two epidemic outbreaks in a limited geographical region and performed phylogeographic analyses. We described a spatio-temporal transmission between local strains, which were originated in the center of the analyzed area and then spread to others. Interestingly, that central area reported the highest population density of the region and also showed overcrowding. This information should be considered by public health systems to evaluate vaccination at all ages in those areas to decrease viral transmission and in lower density populations only susceptible children should be vaccinated., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Human respiratory syncytial virus (HRSV) is the main viral cause of acute lower respiratory tract infections (LRTI) in children worldwide. In recent years, several preclinical trials with vaccine candidates have been reported. It is in this sense that molecular epidemiological studies become important. Understanding viral dispersion patterns before and after the implementation of a vaccine can provide insight into the effectiveness of the control strategies. In this work we analyzed the molecular epidemiology of HRSV-A over a period of sixteen years (1999-2014) in Buenos Aires. By bioinformatic tools we analyzed 169 sequences of the G glycoprotein gene from hospitalized pediatric patients with LRTI. We found that GA2 was the most prevalent genotype (73.35%). GA5 genotype co-circulated in our region until 2009 when it was no longer detected, except in 2011. The recently globally emerging ON1 lineage with a 72-nt duplication increased its frequency to become the only lineage detected in Buenos Aires in 2014. By discrete phylogeographic analysis of global ON1 strains we could determine that Panama could be the location of the MRCA dated June 20, 2010; and this lineage could be introduced in Argentina from Spain in April 2011. This analysis also showed temporary and geographical clustering of ON1 strains observed as phylogenetic clades with strains exclusively associated from a single country, nevertheless among our 44 ON1 strains from three outbreaks (2012-2014) we could also detect posterior reintroductions and circulation from United States, Cuba, South Korea, and Spain. The continuous phylogeographic analysis of one sublineage of Argentine ON1 strains allowed us to establish that there could be a local clustering of some strains even in neighborhoods. This work shows the potential of this type of bioinformatic tools in the context of a future vaccine surveillance network to trace the spread of new genetic lineages in human populations., (Copyright © 2016 Elsevier B.V. All rights reserved.)