Human Respiratory Syncytial Virus in Children with Acute Respiratory Tract Infections in China

Abstract

Human respiratory syncytial virus (HRSV) is a major cause of lower respiratory tract infections (LRTIs) among infants and young children worldwide and is also a major cause of morbidity in children under 1 year of age (2). Bronchiolitis and pneumonia, which are attributed to HRSV infection, are observed most frequently during the first few months of life (7). Almost all children are infected with HRSV by 2 years of age, and half of all children experience two infections (8, 13).Based on genetic and antigenic variations in structural proteins, HRSV isolates have been subdivided into two major antigenic groups (i.e., A and B), and both subgroups are associated with different severities of infection (15,18,(22)(23)(24). The nucleotide and deduced amino acid sequence similarities are 67% and 53% between group A and group B strains, respectively (11, 19). Antigenic variability is thought to contribute to the capacity of the virus to infect people repeatedly and cause yearly outbreaks. These characteristics may pose a challenge for vaccine design and development (27). The G protein, a surface-expressed glycoprotein that is associated with attachment of the virus, shows the largest antigenic and genetic differences between the two antigenic HRSV subgroups and is one of the targets for neutralization and protective antibody responses (1, 19). The G protein contains two hypervariable regions; the second variable region, which corresponds to the C-terminal region of the G protein (HVR2), reflects overall G protein gene variability and has been analyzed in molecular epidemiological studies (9,(25)(26)(27)(28).Although HRSV has been recognized as an important agent, no effective vaccine is currently available for prophylaxis and there is no effective antiviral treatment against current HRSV infections. The importance of strain differences in relation to clinical features and vaccine development has not been fully elucidated (8,22). In the present study, 894 children with acute respiratory tract infections (ARTIs) were examined over three consecutive seasons for the presence of HRSV, and HRSV strains were genotyped by sequencing HVR2. Demographic and clinical information was collected from all patients. The prevalence and clinical and molecular characterization of HRSV genotypes were further analyzed. MATERIALS AND METHODSPatients and specimens. From December 2006 to March 2009, 894 nasopharyngeal aspirates (NPAs) were collected from children with ARTIs on Tuesday every week in the First Hospital of Lanzhou University, China. ARTIs were classified according to WHO definitions (38). Informed consent was obtained from the parents of all children who provided specimens. The study protocol was approved by the hospital ethics committee. All NPA specimens were collected and transported immediately to the laboratory at the National Institute for Viral

Molecular Characterization of Circulating Respiratory Syncytial Virus (RSV) Genotypes in Gilgit Baltistan Province of Pakistan during 2011-2012 Winter Season

“…Furthermore, the S247P amino acid substitution observed in the duplicated 20 amino acid region was also absent in the Gilgit RSV B viruses which puts them closer to the earlier described prototype BA strain. These RSV-B isolates also carry a six-nucleotide deletion after residue 489 (amino acid positions 159-160) in-frame deletion previously reported in Chinese strains from Chongqing and other studies [15,41]. Even though the number of RSV-B viruses analyzed in this study is too small, it is expected that future analysis of Pakistani strains will be helpful in understanding the significance of these mutations with a larger number of RSV-B isolates from consecutive seasons.…”

“…This is understandable because limited sequence data is available at present time on the prevalence of RSV in SouthEast Asia and eastern Mediterranean region [10,40,51]. Conversely it is also known that viruses from different regions and various seasons apart may be more similar than those isolated from same area in one season [8,25,30,41-43]. …”

“…The BA genotype was subsequently detected in Japan in 2003 [44] later in China [41], Thailand [37,46,47], South Africa [9], Brazil [52] and India [8], becoming the predominant HRSV-B genotype in circulation worldwide. All the group B strains carry the characteristic 60 nucleotide duplication, conserved stop codons, and a six nucleotide deletion in HVR1 [13,30,41,48]. Previous studies have reported variable G protein lengths for RSV B viruses isolated during the same season [5,30,41,49].…”

“…All the group B strains carry the characteristic 60 nucleotide duplication, conserved stop codons, and a six nucleotide deletion in HVR1 [13,30,41,48]. Previous studies have reported variable G protein lengths for RSV B viruses isolated during the same season [5,30,41,49]. However, among the PG RSV B strains, the deduced amino acid homologies in HRV2 were 98 to 100% and only one G protein length of 319 aa was observed.…”

Viral/bacterial respiratory tract co-infections in children

“…More recent studies comparing disease severity between genotypes have also been inconclusive, with some studies finding no difference in severity measures between circulating RSV-A and RSV-B strains (200,202,220), and others finding increased severity in RSV-A genotypes (221,222).…”