Respiratory Syncytial Virus-A ON1 Genotype Emergence in Central Mexico in 2009 and Evidence of Multiple Duplication Events

Background. Respiratory syncytial virus (RSV) is a leading cause of respiratory infections. An RSV-A genotype (ON1) that contains a 72-nt duplication was reported in 2012 and has since extended worldwide. Methods. We analyzed 345 respiratory samples obtained between 2003 and 2014 to assess the relevance of ON1 infections. Nucleotidic and deduced amino acid sequences from viruses detected in San Luis Potosi and sequences previously reported were analyzed. Results. RSV ON1 was detected in 105 samples. The earliest case of ON1 infection was detected in November 2009, almost 1 year prior to detection of this virus in Canada. Amino acid sequence analysis of the duplication region showed the presence of Y273N and L274P substitutions in RSV GA2 viruses that, when combined, resulted in 4 different GXXSPSQ sequence motifs at positions 272-278. Three of these motifs were present in both the original and duplicated regions of ON1 strains. Additional signature amino acid substitutions were observed in ON1 strains that have the different sequence motifs. Conclusions. ON1 strains include viruses that appear to be the result of at least 3 independent duplication events. Molecular data of strains from diverse geographical regions should help define the frequency and implications of this evolution mechanism.