The human respiratory syncytial virus (HRSV) is the main etiological agent of acute lower respiratory infections (ALRIs) in breastfed babies, infants, elderly, and immunocompromised patients. In Peru, acute respiratory infections due to HRSV can reach up to 80% of cases according to seasonality, which causes severe bronchiolitis and pneumonia.
The objective of this study is the molecular characterization of the HRSV-A genotypes that circulate in the regions of the Peruvian coast.
Materiales y Métodos:
Sixteen hundred ninety-eight (1,698) samples were collected from hospitalized pediatric patients who had a clinical diagnosis of ARI during 2009-2020. To identify the HRSV-A, samples were analyzed through real-time PCR (RT-PCR) and then the partial glycoprotein (G) gene was amplified and sequenced for the genotypification and characterization. The phylogenetic reconstruction and estimation of the time to the most recent common ancestor (TMRCA) was conducted by Bayesian inference that uses the Markov chain Monte Carlo (MCMC) algorithm.
From the total analyzed samples, 351 (20.67%) cases were positive for HRSV, 211 (60.11%) cases of which were positive for HRSV-A. The phylogenetic inference of 53 nucleotide sequences showed the co-circulation of the NA1 and ON1 genotypes of HRSV-A; furthermore, it was identified that the ON1[1.1]-ON1[1.4] lineages are among the population, and it was reported a possible autochthonous lineage, ON1[1.6], which characterizes by forming an own monophyletic group and showing 3 exclusive point mutations, S250F, S267L and T293I, in the second hypervariable region of G protein that decrease the number of possible O-linked glycosylation sites and, therefore, alter the antigenic structure of the virus and have an impact in its infection capacity. The results of this study show that ON1 genotype appeared around year 2008 and would be evolving with an approximate rate of 3.35 × 10 −3 substitutions per site per year in the third C-terminal of G protein. The study reports the oldest strains of the ON1 genotype, which were isolated in May 2009 in Lima and, therefore, suggest that ON1 would have firstly arisen in South America, possibly in Peru.
Discusión / Conclusiones:
The analysis of the partial G gene reveals that the ON1 genotype diversification would have begun in South America, and the diversity found inside the HRSV-A highlights the need to have an active genomic surveillance plan for HRSV and other ARI-causing viruses.