Genetic variability in G2 and F2 region between biological clones of human respiratory syncytial virus with or without host immune selection pressure

Human respiratory syncytial virus (HRSV) is an important respiratory pathogens amongchildren between zero-five years old. Host immunity and viral genetic variability areimportant factors that can make vaccine production difficult. In this work,differences between biological clones of HRSV were detected in clinical samples inthe absence and presence of serum collected from children in the convalescent phaseof the illness and from their biological mothers. Viral clones were selected byplaque assay in the absence and presence of serum and nucleotide sequences of the G2and F2 genes of HRSV biological clones were compared. One non-synonymous mutation wasfound in the F gene (Ile5Asn) in one clone of an HRSV-B sample and one non-synonymousmutation was found in the G gene (Ser291Pro) in four clones of the same HRSV-Bsample. Only one of these clones was obtained after treatment with the child''s serum.In addition, some synonymous mutations were determined in two clones of the HRSV-Asamples. In conclusion, it is possible that minor sequences could be selected by hostantibodies contributing to the HRSV evolutionary process, hampering the developmentof an effective vaccine, since we verify the same codon alteration in absence andpresence of human sera in individual clones of BR-85 sample.