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 among children between zero-five years old. Host immunity and viral genetic variability are important factors that can make vaccine production difficult. In this work, differences between biological clones of HRSV were detected in clinical samples in the absence and presence of serum collected from children in the convalescent phase of the illness and from their biological mothers. Viral clones were selected by plaque assay in the absence and presence of serum and nucleotide sequences of the G2 and F2 genes of HRSV biological clones were compared. One non-synonymous mutation was found in the F gene (Ile5Asn) in one clone of an HRSV-B sample and one non-synonymous mutation was found in the G gene (Ser291Pro) in four clones of the same HRSV-B sample. 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-A samples. In conclusion, it is possible that minor sequences could be selected by host antibodies contributing to the HRSV evolutionary process, hampering the development of an effective vaccine, since we verify the same codon alteration in absence and presence of human sera in individual clones of BR-85 sample.

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 among children between zero-five years old. Host immunity and viral genetic variability are important factors that can make vaccine production difficult. In this work, differences between biological clones of HRSV were detected in clinical samples in the absence and presence of serum collected from children in the convalescent phase of the illness and from their biological mothers. Viral clones were selected by plaque assay in the absence and presence of serum and nucleotide sequences of the G2 and F2 genes of HRSV biological clones were compared. One non-synonymous mutation was found in the F gene (Ile5Asn) in one clone of an HRSV-B sample and one non-synonymous mutation was found in the G gene (Ser291Pro) in four clones of the same HRSV-B sample. 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-A samples. In conclusion, it is possible that minor sequences could be selected by host antibodies contributing to the HRSV evolutionary process, hampering the development of an effective vaccine, since we verify the same codon alteration in absence and presence of human sera in individual clones of BR-85 sample.

Molecular epidemiology of the SH (small hydrophobic) gene of human respiratory syncytial virus (HRSV), over 2 consecutive years.

Human respiratory syncytial virus (HRSV) strains were isolated from nasopharyngeal aspirates collected from 965 children between 2004 and 2005, yielding 424 positive samples. We sequenced the small hydrophobic protein (SH) gene of 117 strains and compared them with other viruses identified worldwide. Phylogenetic analysis showed a low genetic variability among the isolates but allowed us to classify the viruses into different genotypes for both groups, HRSVA and HRSVB. It is also shown that the novel BA-like genotype was well segregated from the others, indicating that the mutations are not limited to the G gene.

Comparison between ectodomain and G2 region of G glycoprotein for genotyping of HRSV

The Human Respiratory Syncytial Virus (HRSV), isolated in 1955, is the main cause of hospitalization of babies and infants with respiratory illness. Several studies have been conducted worldwide aiming the development of a safe and effective vaccine against HRSV. The G2 region of glycoprotein G is used as genotyping default. In the present study, we performed a phylogenetic analysis of G protein and a comparative study between G2 region and ectodomain of attachment glycoprotein. Fifty-three nasal swab samples from children less than 5 years old and presenting symptoms of acute respiratory illness, assisted at the University Hospital (UH) of University of Sao Paulo (USP) in 2004, were submitted to sequencing by PCR and compared with GenBank sequences. We concluded that the G2 region is adequate for HRSV genotyping.

O vírus respiratório sincicial humano (HRSV), isolado em 1955, é a principal causa da hospitalização de bebês e crianças pequenas com sintomas de doença respiratória. No mundo inteiro, vários estudos para o desenvolvimento de uma vacina segura e eficiente contra o HRSV têm tido alta prioridade. A região G2 da glicoproteína G é usada como padrão para genotipagem do HRSV. Neste estudo, foi realizada a análise filogenética da glicoproteína G e o estudo comparativo entre a região G2 e o ectodomínio dessa glicoproteína. Cinquenta e três amostras de swab nasal de crianças com menos de cinco anos de idade, apresentando doença respiratória aguda, atendidas no Hospital Universitário (HU) da Universidade de São Paulo durante o ano de 2004, foram submetidas a sequenciamento por PCR e comparadas com seqüências do GenBank. A região G2 mostrou ser adequada para a genotipagem do HRSV.