Genetic variability of group A and B human respiratory syncytial viruses isolated from 3 provinces in China

Molecular epidemiology and characteristics of respiratory syncytial virus among hospitalized children in Guangzhou, China

BACKGROUND

Human respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection and hospitalization, especially in children. Highly mutagenic nature and antigenic diversity enable the RSV to successfully survive in human population. We conducted a molecular epidemiological study during 2017-2021 to investigate the prevalence and genetic characteristics of RSV.

METHODS

A total of 6499 nasopharyngeal (NP) swabs were collected from hospitalized children at Department of Pediatrics, Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou, Guangdong, China. All NP swab specimens were preliminary screened for common respiratory viruses and then tested for RSV using specific PCR assays. Partial G genes of RSV were amplified for phylogenetic analysis and genetic characterization.

RESULTS

The overall detection rate for common respiratory viruses was 16.12% (1048/6499). Among those, 405 specimens (6.20%, 405/6499) were found positive for RSV. The monthly distribution of RSV and other respiratory viruses was variable, and the highest incidence was recorded in Autumn and Winter. Based on the sequencing of hypervariable region of G gene, 93 RSV sequences were sub-grouped into RSV-A (56, 60.2%) and RSV-B (37, 39.8%). There was no coinfection of RSV-A and RSV-B in the tested samples. Phylogenetic analysis revealed that RSV-A and RSV-B strains belonged to ON1 and BA9 genotypes respectively, indicating predominance of these genotypes in Guangzhou. Several substitutions were observed which may likely change the antigenicity and pathogenicity of RSV. Multiple glycosylation sites were noticed, demonstrating high selection pressure on these genotypes.

CONCLUSION

This study illustrated useful information about epidemiology, genetic characteristics, and circulating genotypes of RSV in Guangzhou China. Regular monitoring of the circulating strains of RSV in different parts of China could assist in the development of more effective vaccines and preventive measures.

ON-1 and BA-IX Are the Dominant Sub-Genotypes of Human Orthopneumovirus A&B in Riyadh, Saudi Arabia

Human orthopneumovirus (HOPV) is the major viral pathogen responsible for lower respiratory tract infections (LRTIs) in infants and young children in Riyadh, Saudi Arabia. Yet, predominant HOPV subtypes circulating in this region and their molecular and epidemiological characteristics are not fully ascertained. A total of 300 clinical samples involving nasopharyngeal aspirates (NPAs), throat swabs, and sputum were collected during winter seasons of 2019/2020 and 2021/2022 for HOPV subtyping and genotyping. Of the 300 samples, HOPV was identified in 55 samples (18.3%) with a distinct predominance of type A viruses (81.8%) compared to type B viruses (18.2%). Importantly, the ON1 strain of HOPV-A and BA-IX strain of HOPV-B groups were found to be responsible for all the infections. Sequence analysis revealed a duplication region within 2nd HVR of G protein gene of ON1 and BA-IX strains. This nucleotide duplication exerted a profound effect on protein length and affinity towards cell receptors. Further, these modifications may aid the HOPV in immune evasion and recurrent infections. Data from this study showed that ON-1 genotype of HOPV-A and BA-IX genotype of HOPV-B were dominant in Riyadh, Saudi Arabia. Further, a duplication of sequence within 2nd HVR of G protein gene was found.

An Outbreak of Severe Neonatal Pneumonia Caused by Human Respiratory Syncytial Virus BA9 in a Postpartum Care Centre in Shenyang, China

Human respiratory syncytial virus (HRSV) is a major pathogen of lower respiratory tract infections in children (<5 years) and older individuals, with outbreaks mainly reported among infants in hospital pediatric departments and intensive care units (ICUs). An outbreak of severe neonatal pneumonia occurred in a postpartum center in Shenyang city, China, from January to February 2021. In total, 34 respiratory samples were collected from 21 neonates and 13 nursing staff. The samples were screened for 27 pathogens using a TaqMan low-density array, and 20 samples tested positive for HRSV, including 16 neonates and 4 nursing staff samples. Among the 16 hospitalized neonates, seven were admitted to an ICU and nine to general wards. Four of the nursing staff had asymptomatic infections. To investigate the genetic characteristics of the HRSV responsible for this outbreak, the second hypervariable region (HVR2) sequences of the G gene were obtained from six neonates and two nursing staff. Phylogenetic analyses revealed that all eight sequences (SY strains) were identical, belonging to the HRSV BA9 genotype. Our findings highlight the necessity for strict hygiene and disease control measures so as to prevent cross-infection and further avoid potential outbreaks of severe infectious respiratory diseases. IMPORTANCE Human respiratory syncytial virus (HRSV) is one of the leading causes of acute lower respiratory infections (ALRI) worldwide. In this study, we first reported an outbreak of severe neonatal pneumonia caused by HRSVB BA9 at a postpartum care center in mainland China. Among 20 confirmed cases, 16 were hospitalized neonates with 7 in the ICU ward, and the other four were nursing staff with asymptomatic infections. Our findings highlighted the importance of preventing cross-infection in such postpartum centers.

A multi-center study on Molecular Epidemiology of Human Respiratory Syncytial Virus from Children with Acute Lower Respiratory Tract Infections in the Mainland of China between 2015 and 2019

Human respiratory syncytial virus (RSV) is a major pathogen of acute lower respiratory tract infection among young children. To investigate the prevalence and genetic characteristics of RSV in China, we performed a molecular epidemiological study during 2015-2019. A total of 964 RSV-positive specimens were identified from 5529 enrolled patients during a multi-center study. RSV subgroup A (RSV-A) was the predominant subgroup during this research period except in 2016. Totally, 535 sequences of the second hypervariable region (HVR-2) of the G gene were obtained. Combined with 182 Chinese sequences from GenBank, phylogenetic trees showed that 521 RSV-A sequences fell in genotypes ON1 (512), NA1 (6) and GA5 (3), respectively; while 196 RSV-B sequences fell in BA9 (193) and SAB4 (3). ON1 and BA9 were the only genotypes after December 2015. Genotypes ON1 and BA9 can be separated into 10 and 7 lineages, respectively. The HVR-2 of genotype ON1 had six amino acid changes with a frequency more than 10%, while two substitutions H258Q and H266L were co-occurrences. The HVR-2 of genotype BA9 had nine amino acid substitutions with a frequency more than 10%, while the sequences with T290I and T312I were all from 2018 to 2019. One N-glycosylation site at 237 was identified among ON1 sequences, while two N-glycosylation sites (296 and 310) were identified in the 60-nucleotide duplication region of BA9. To conclusion, ON1 and BA9 were the predominant genotypes in China during 2015-2019. For the genotypes ON1 and BA9, the G gene exhibited relatively high diversity and evolved continuously.

Systematic Review of the Respiratory Syncytial Virus (RSV) Prevalence, Genotype Distribution, and Seasonality in Children from the Middle East and North Africa (MENA) Region

Respiratory syncytial virus (RSV) is one of the most common viruses to infect children worldwide and is the leading cause of lower respiratory tract illness (LRI) in infants. This study aimed to conduct a systematic review by collecting and reviewing all the published knowledge about the epidemiology of RSV in the Middle East and North Africa (MENA) region. Therefore, we systematically searched four databases; Embase, Medline, Scopus, and Cochrane databases from 2001 to 2019 to collect all the information related to the RSV prevalence, genotype distribution, and seasonality in children in MENA region. Our search strategy identified 598 studies, of which 83 met our inclusion criteria, which cover the past 19 years (2000–2019). Odds ratio (OR) and confidence interval (CI) were calculated to measure the association between RSV prevalence, gender, and age distribution. An overall prevalence of 24.4% (n = 17,106/69,981) of respiratory infections was recorded for RSV. The highest RSV prevalence was reported in Jordan (64%, during 2006–2007) and Israel (56%, 2005–2006). RSV A subgroup was more prevalent (62.9%; OR = 2.9, 95%CI = 2.64–3.13) than RSV B. RSV was most prevalent in children who were less than 12 months old (68.6%; OR = 4.7, 95%CI = 2.6–8.6) and was higher in males (59.6%; OR = 2.17, 95%CI = 1.2–3.8) than in female infants. Finally, the highest prevalence was recorded during winter seasons in all countries, except for Pakistan. RSV prevalence in the MENA region is comparable with the global one (24.4% vs. 22%). This first comprehensive report about RSV prevalence in the MENA region and our data should be important to guide vaccine introduction decisions and future evaluation.

Analysis of genetic variability of respiratory syncytial virus groups A and B in Kuwait

Respiratory syncytial virus (RSV) is the most frequently identified viral agent in infants, children, and elderly people with acute respiratory tract infections (ARTIs). This study is the only one of its kind in Kuwait, and its purpose was to investigate the genetic variability of the G protein gene in RSV strains prevalent in Kuwait. Respiratory samples were collected from patients with ARTIs in various hospitals in Kuwait and subjected to reverse transcription PCR (RT-PCR) amplifying a fragment of the G gene of RSV. A total of 305 samples were collected between January and mid-December 2016, and 77 (25.2%) were positive for RSV. Group A viruses were predominant over group B viruses; the RSV-A group was detected in 52 (67.5%) of the positive samples, while the RSV-B group was detected in 25 (32.5%) of the positive samples. Phylogenetic analysis showed that all RSV-A strains grouped into eight clusters of identical sequences of untyped strains. Twelve RSV-B strains, on the other hand, belonged to the RSV-B/BA10 genotype, while the rest were untyped. These data suggest that new and untyped strains of RSV-A group likely predominated in Kuwait and that the BA10 genotype of the RSV-B group became the dominant genotype in the 2016 season.

Emergence of BA9 genotype of human respiratory syncytial virus subgroup B in China from 2006 to 2014

A study was conducted to investigate the circulation of HRSV subgroup B (HRSVB) in China in recent years. HRSVB sequences from 365 samples collected in 1991, 2004 and 2008-2014 in China, together with 332 Chinese HRSVB sequences obtained from GenBank were analyzed to determine the geographic and yearly distribution of HRSVB. Phylogenetic analysis revealed these HRSVB sequences clustered into 4 genotypes with different frequencies: BA (83%), CB1 (11%), SAB (3.0%) and GB3 (0.7%). Between 2005 and 2013, there was a co-circulation of BA and non-BA genotypes in China. Genotypes BA9 and BA10 were two of the main BA genotypes detected in this study. Genotype BA9 was first detected in China in 2006 and became the predominant HRSVB genotype circulating in China from 2008 to 2014. Three different lineages were detected for both genotypes BA9 and BA10. Time to the most recent common ancestor for genotypes BA9 and BA10 was estimated for years 1997 and 1996, respectively. Results of this study not only contribute to the understanding of the circulation pattern, but also the phylogenetic pattern and evolution of HRSVB in China from 1991 to 2014.

Emergence of ON1 genotype of human respiratory syncytial virus subgroup A in China between 2011 and 2015

A molecular epidemiological study of human respiratory syncytial virus (HRSV) was conducted to examine the distribution of its subgroups and genotypes, as well as to identify its transmission pattern in China. A total of 705 samples collected from 9 provinces in China between January 2008 and February 2015 were identified as HRSV-positive and were subsequently sequenced. Of these, 336 samples were HRSV subgroup A (HRSVA), 368 samples were HRSV subgroup B (HRSVB), and 1 sample contained both HRSVA and HRSVB. These 705 HRSV sequences, together with 766 HRSV sequences downloaded from GenBank, were analyzed to understand the recent circulation patterns of HRSV in China. HRSVB predominated in the 2008/2009 and 2009/2010 seasons, whereas HRSVA predominated in the 2010/2011 and 2011/2012 seasons; HRSVA and HRSVB co-circulated during 2012/2013 and 2014/2015. Phylogenetic analysis showed most of the HRSVA sequences clustered into 2 genotypes, namely, NA1 and ON1. The ON1 genotype was first detected in China in 2011, and it quickly replaced the NA1 genotype to become the most prevalent HRSVA genotype circulating in China between 2013 and 2015. Continuous epidemiological surveillance and molecular characterization of HRSV should be conducted to monitor the evolution of HRSV in China.

Co-Circulation of 72bp Duplication Group A and 60bp Duplication Group B Respiratory Syncytial Virus (RSV) Strains in Riyadh, Saudi Arabia during 2014

Respiratory syncytial virus (RSV) is an important viral pathogen of acute respiratory tract infection (ARI). Limited data are available on molecular epidemiology of RSV from Saudi Arabia. A total of 130 nasopharyngeal aspirates were collected from children less than 5 years of age with ARI symptoms attending the Emergency Department at King Khalid University Hospital and King Fahad Medical City, Riyadh, Saudi Arabia between October and December, 2014. RSV was identified in the 26% of the hospitalized children by reverse transcriptase PCR. Group A RSV (77%) predominated during the study as compared to group B RSV (23%). The phylogenetic analysis of 28 study strains clustered group A RSV in NA1 and ON1 genotypes and group B viruses in BA (BA9) genotype. Interestingly, 26% of the positive samples clustered in genotypes with duplication in the G protein gene (ON1 for group A and BA for group B). Both the genotypes showed enhanced O-linked glycosylation in the duplicated region, with 10 and 2 additional sites in ON1 and BA respectively. Selection pressure analysis revealed purifying selection in both the ON1 and BA genotypes. One codon each in the ON1 (position 274) and BA genotypes (position 219) were positively selected and had high entropy values indicating variations at these amino acid positions. This is the first report describing the presence of ON1 genotype and the first report on co-circulation of two different genotypes of RSV with duplication in the G protein gene from Saudi Arabia. The clinical implications of the simultaneous occurrence of genotypes with duplication in G protein gene in a given population especially in the concurrent infections should be investigated in future. Further, the ongoing surveillance of RSV in this region will reveal the evolutionary trajectory of these two genotypes with duplication in G protein gene from largest country in the Middle East.

Epidemiology of 11 respiratory RNA viruses in a cohort of hospitalized children in Riyadh, Saudi Arabia

Respiratory tract infections are a principal cause of illness and mortality in children worldwide and mostly caused by viruses. In this study, the epidemiology of 11 respiratory RNA viruses was investigated in a cohort of hospitalized children at a tertiary referral center in Riyadh from February 2008 to March 2009 using conventional and real‐time monoplex RT‐PCR assays. Among 174 nasopharyngeal aspirates, respiratory syncytial virus (RSV) was detected in 39 samples (22.41%), influenza A virus in 34 (19.54%), metapneumovirus (MPV) in 19 (10.92%), coronaviruses in 14 (8.05%), and parainfluenza viruses (PIVs) in 11 (6.32%). RSV, PIVs and coronaviruses were most prevalent in infants less than 6 months old, whereas MPV and influenza A virus were more prominent in children aged 7–24 and 25–60 months, respectively. The majority of the viruses were identified during winter with two peaks observed in March 2008 and January 2009. The presented data warrants further investigation to understand the epidemiology of respiratory viruses in Saudi Arabia on spatial and temporal basis. J. Med. Virol. 88:1086–1091, 2016. © 2015 Wiley Periodicals, Inc.

Functional Analysis of the 60-Nucleotide Duplication in the Respiratory Syncytial Virus Buenos Aires Strain Attachment Glycoprotein

There are two subgroups of respiratory syncytial virus (RSV), A and B, and within each subgroup, isolates are further divided into clades. Several years ago, multiple subgroup B isolates which contained a duplication of 60 nucleotides in the glycoprotein (G) gene were described. These isolates were given a new clade designation of BA based on the site of isolation, Buenos Aires, Argentina. BA RSV strains have since become the predominant circulating clade of RSV B viruses. We hypothesized that the duplicated region in G serves to enhance the function of G in the virus life cycle. We generated recombinant viruses that express a consensus BA G gene or a consensus BA G gene lacking the duplication (GΔdup). We determined that the duplicated region functions during virus attachment to cells. Additionally, we showed that in vitro, the virus containing the duplication has a fitness advantage compared to the virus without the duplication. Our data demonstrate that the duplicated region in the BA strain G protein augments virus attachment and fitness.

IMPORTANCE

Respiratory syncytial virus (RSV) is an important pathogen for infants for which there is no vaccine. Different strains of RSV circulate from year to year, and the predominating strains change over time. Subgroup B RSV strains with a duplication in the attachment glycoprotein (G) emerged and then became the dominant B genotype. We found that a recombinant virus harboring the duplication bound more efficiently to cells and was more fit than a recombinant strain lacking the duplication. Our work advances a mechanism for an important natural RSV mutation.

Molecular characterization of human respiratory syncytial virus subtype B: a novel genotype of subtype B circulating in China

Human respiratory syncytial virus (HRSV) is major pathogen of lower respiratory tract infections in infants and young children worldwide. There have been many studies regarding HRSV subgroup A (HRSV-A) G protein genetic variability but little information about HRSV subtype B (HRSV-B) G protein genetic diversity and molecular evolution in China. Thus, a survey of the molecular epidemiology and evolution of the G protein in China is of high importance. In this study, the circulation and genetic diversity of HRSV in Chongqing, Southwestern China, from June 2009 to May 2013, were investigated. A total of 3,167 nasopharyngeal aspirates were obtained in this study, and it was found that HRSV-B predominated in the 2009-2010 and 2012-2013 epidemic seasons. This study identified the genetic variability of the glycoprotein G gene among 102 HRSV-B strains isolated by cell culture from Chongqing nasopharyngeal aspirates, and 68 Chinese HRSV-B sequences were deposited in GenBank. Genotyping and phylogenetic analysis revealed that the HRSV-B strains were clustered into three genotypes: BA (n = 111, 65.29%), GB3 (n = 5, 2.94%), and a new GB genotype (n = 54, 31.77%) named GB5. The GB5 strains varied from other genotypes in the central conserved region and N-glycosylation sites. The estimated evolutionary rate of Chinese HRSV-B was 2.01 × 10(-3) nucleotide substitutions/site/year, which is similar to the reports from Belgium and the Netherlands with 1.95 × 10(-3) and 2.78 × 10(-3) nucleotide substitutions/site/year, respectively. This study provides data on the circulating pattern and molecular characterization of HRSV-B genotypes in China during four consecutive years and may contribute to HRSV vaccine development.

Genotype circulation pattern of human respiratory syncytial virus in Iran

In order to have information on the molecular epidemiology and genetic circulation pattern of human respiratory syncytial virus (HRSV) in Iran, we studied the genetic variability of both group A and B HRSV strains during seven consecutive years by sequencing the hypervariable C-terminal domain of G protein. A total of 485 children <2years of age who were negative for influenza viruses, screened for the presence of HRSV in this research. HRSV was detected in 94 (19.38%) of the samples using nested RT-PCR. Group A viruses were isolated during each year, while group B viruses were isolated during 2009 and 2013. Phylogenetic analysis showed that all HRSV group A viruses belonged to three genotypes: GA1, GA2, GA5 and the group B viruses were in BA genotype.

Group B strains of human respiratory syncytial virus in Saudi Arabia: molecular and phylogenetic analysis

The genetic variability and circulation pattern of human respiratory syncytial virus group B (HRSV-B) strains, identified in Riyadh during the winters of 2008 and 2009, were evaluated by partial sequencing of the attachment (G) protein gene. The second hypervariable region (HVR-2) of G gene was amplified by RT-PCR, sequenced and compared to representatives of different HRSV-B genotypes. Sequence and phylogenetic analysis revealed that all Saudi strains belonged to the genotype BA, which is characterized by 60-nucleotide duplication at HVR-2. Only strains of 2008 were clustered with subgroup BA-IV, while those isolated at 2009 were clustered among the most recent subgroups (particularly BA-X and CB-B). Amino acid sequence analysis demonstrated 18 amino acid substitutions in Saudi HRSV-B strains; among which five are specific for individual strains. Furthermore, two potential N-glycosylation sites at residues 230 and 296 were identified for all Saudi strains, and an additional site at amino acid 273 was found only in Riyadh 28/2008 strain. O-glycosylation was predicted in 42-43 sites, where the majority (no = 38) are highly conserved among Saudi strains. The average ratio between non-synonymous and synonymous mutations (ω) implied stabilizing selection pressure on G protein, with evidences of positive selection on certain Saudi strains. This report provides preliminary data on the circulation pattern and molecular characteristics of HRSV-B strains circulating in Saudi Arabia.

Molecular epidemiology of respiratory viruses in virus-induced asthma

Acute respiratory illness (ARI) due to various viruses is not only the most common cause of upper respiratory infection in humans but is also a major cause of morbidity and mortality, leading to diseases such as bronchiolitis and pneumonia. Previous studies have shown that respiratory syncytial virus (RSV), human rhinovirus (HRV), human metapneumovirus (HMPV), human parainfluenza virus (HPIV), and human enterovirus infections may be associated with virus-induced asthma. For example, it has been suggested that HRV infection is detected in the acute exacerbation of asthma and infection is prolonged. Thus it is believed that the main etiological cause of asthma is ARI viruses. Furthermore, the number of asthma patients in most industrial countries has greatly increased, resulting in a morbidity rate of around 10-15% of the population. However, the relationships between viral infections, host immune response, and host factors in the pathophysiology of asthma remain unclear. To gain a better understanding of the epidemiology of virus-induced asthma, it is important to assess both the characteristics of the viruses and the host defense mechanisms. Molecular epidemiology enables us to understand the pathogenesis of microorganisms by identifying specific pathways, molecules, and genes that influence the risk of developing a disease. However, the epidemiology of various respiratory viruses associated with virus-induced asthma is not fully understood. Therefore, in this article, we review molecular epidemiological studies of RSV, HRV, HPIV, and HMPV infection associated with virus-induced asthma.

Genetic diversity in the G protein gene of group A human respiratory syncytial viruses circulating in Riyadh, Saudi Arabia

Human respiratory syncytial virus (HRSV) is a frequent cause of hospitalization and mortality in children worldwide. The molecular epidemiology and circulation pattern of HRSV in Saudi Arabia is mostly uncharted. In the current study, the genetic variability and phylogenetic relationships of HRSV type A strains circulating in Riyadh Province were explored. Nasopharyngeal aspirates were collected from hospitalized children with acute respiratory symptoms during the winter-spring seasons of 2007/08 and 2008/09. Among 175 samples analyzed, 39 (22.3 %) were positive for HRSV by one-step RT-PCR (59 % type A and 41 % type B). Propagation of positive samples in HEp-2 cells permitted the recovery of the first Saudi HRSV isolates. Genetic variability among Saudi HRSV-A strains was evaluated by sequence analysis of the complete attachment (G) protein gene. The nucleotide sequence was compared to representatives of the previously identified HRSV-A genotypes. Sequence and phylogenetic analysis showed that the strains examined in this study were very closely related at both the nucleotide and amino acid level, and all of them are clustered in the GA2 genotype (and mostly belonged to the NA-1 subtype). A total of 23 mutation sites, 14 of which resulted in an amino acid change, were recorded only in Saudi strains. This is the first report on genetic diversity of HRSV-A strains in Saudi Arabia. Further analysis of strains on a geographical and temporal basis is needed to fully understand HRSV-A circulation patterns in Saudi Arabia.

Circulation of human respiratory syncytial virus strains among hospitalized children with acute lower respiratory infection in malaysia

Human respiratory syncytial virus (RSV) is a major viral pathogen associated with acute lower respiratory tract infections (ALRTIs) among hospitalized children. In this study, the genetic diversity of the RSV strains was investigated among nasopharyngeal aspirates (NPA) taken from children less than 5 years of age hospitalized with ALRTIs in Hospital Serdang, Malaysia. A total of 165 NPA samples were tested for the presence of RSV and other respiratory viruses from June until December 2009. RSV was found positive in 83 (50%) of the samples using reverse transcription polymerase chain reaction (RT-PCR). Further classification of 67 RSV strains showed that subgroups A and B comprised 11/67 (16.4%) and 56/67 (83.6%) of the strains, respectively. The second hypervariable region at the carboxyl-terminal of the G gene was amplified and sequenced in order to do phylogenetic study. The phylogenetic relationships of the samples were determined separately for subgroups A and B using neighbor joining (NJ), maximum parsimony (MP), and Bayesian inference (BI). Phylogenetic analysis of the 32 sequenced samples showed that all 9 RSV-A strains were clustered within NA1 genotype while the remaining 23 strains of the RSV-B subgroup could be grouped into a clade consisted of strains with 60-nucleotide duplication region. They were further classified into newly discovered BA10 and BA9 genotypes. The present finding suggests the emergence of RSV genotypes of NA1 and BA. This is the first documentation of the phylogenetic relationship and genetic diversity of RSV strains among hospitalized children diagnosed with ALRTI in Serdang, Malaysia.

Influence of respiratory syncytial virus strain differences on pathogenesis and immunity

Molecular epidemiology studies have provided convincing evidence of antigenic and sequence variability among respiratory syncytial virus (RSV) isolates. Circulating viruses have been classified into two antigenic groups (A and B) that correlate with well-delineated genetic groups. Most sequence and antigenic differences (both inter- and intra-groups) accumulate in two hypervariable segments of the G-protein gene. Sequences of the G gene have been used for phylogenetic analyses. These studies have shown a worldwide distribution of RSV strains with both local and global replacement of dominant viruses with time. Although data are still limited, there is evidence that strain variation may contribute to differences in pathogenicity. In addition, there is some but limited evidence that RSV variation may be, at least partially, immune (antibody) driven. However, there is the paradox in RSV that, in contrast to other viruses (e.g., influenza viruses) the epitopes recognized by the most effective RSV-neutralizing antibodies are highly conserved. In contrast, antibodies that recognize strain-specific epitopes are poorly neutralizing. It is likely that this apparent contradiction is due to the lack of a comprehensive knowledge of the duration and specificities of the human antibody response against RSV antigens. Since there are some data supporting a group- (or clade-) specific antibody response after a primary infection in humans, it may be wise to consider the incorporation of strains representative of groups A and B (or their antigens) in future RSV vaccine development.

Molecular and demographic analysis of respiratory syncytial virus infection in patients admitted to King Chulalongkorn Memorial Hospital, Thailand, 2007

Please cite this paper as: Boonyasuppayakorn et al. (2010) Molecular and demographic analysis of respiratory syncytial virus infection in King Chulalongkorn Memorial Hospital admitted patients, Thailand, 2007. Influenza and Other Respiratory Viruses 4(5), 313–323.

Objectives:  To preliminary preview the molecular character and its possible clinical correlation of RSV subgroups in Thailand.

Design:  Cross‐sectional analytic design.

Setting:  Admitted acute lower respiratory tract infection patients of King Chulalongkorn Memorial Hospital, Bangkok, during Jun–Dec, 2007 were recruited.

Sample:  Nasopharyngeal aspirations were collected.

Main outcome measures:  All samples were analyzed for the presence of RSV glycoprotein G gene by reverse transcription PCR. Molecular character of each subgroup was determined by sequencing. Admission records were also analyzed for clinical correlations.

Results:  Equal infectivity and severity of both RSV subgroups to the patients was shown. Mixed infection was shown to be as common as each single infection, higher than previously reported. GA2 of subgroup A and BA‐IV of subgroup B were the most widespread genotypes and showed their monophyletic origins. From admission records, either type of infection did not show significantly preference in demographic record or clinical severity. Comorbidity, however, was statistically significant that more congenital heart disease was found in negative RSV cases, while more chronic pulmonary disease was in positive cases. Nevertheless, the clinical severity was insignificantly different suggesting that only patients with chronic pulmonary underlying were prone to be infected with RSV.

Conclusions:  This preliminary RSV study showed prevalence of subgroups, types of infection, and common genotypes in an epidemic, uncorrelated to demography or clinical severity.

Human respiratory syncytial virus in children with acute respiratory tract infections in China

There are limited data on the prevalence and clinical and molecular characterization of human respiratory syncytial virus (HRSV) in children with acute respiratory tract infections (ARTIs) in China. From December 2006 to March 2009, 894 nasopharyngeal aspirates (NPAs) were collected from children under 14 years of age with ARTIs. Samples were screened for HRSV and genotyped by reverse transcription-PCR (RT-PCR) and sequencing. Demographic and clinical information was recorded. A total of 38.14% (341/894) of samples were positive for HRSV. Phylogenetic analysis revealed that 60.4% of the selected 227 RSV strains were GA2, 34.4% were BA, 4.8% were GB2, and 0.4% were GB3. A total of 40.47% of all of the RSV-positive samples were coinfected with other respiratory viruses, and adenovirus was the most common additional respiratory virus. No statistical differences were found in the frequency of diagnosis and symptoms between the coinfection group and monoinfection group. Additionally, no statistical differences were found in epidemiological characterizations or disease severity between genotype BA- and GA2-positive patients, except for a greater frequency of lower respiratory tract infections (LRTIs) (mostly bronchitis)with BA. HRSV is the most important viral pathogen in Chinese children with ARTIs. Four genotypes (i.e., GA2, BA, GB2, and GB3) circulate locally, and the predominant genotype may shift between seasons. Coinfection with other viruses does not affect disease severity. HRSV genotypes were not associated with different epidemiological characterizations or disease severity.

Genetic variability of respiratory syncytial viruses (RSV) prevalent in Southwestern China from 2006 to 2009: emergence of subgroup B and A RSV as dominant strains

Respiratory syncytial virus (RSV) is the most commonly identified viral agent in young children with acute respiratory tract infections (ARIs) and often causes repeated infections throughout life. This study investigated the genetic variability of the attachment (G) protein gene among RSV strains prevalent in southwestern China. Reverse transcription-PCR (RT-PCR) for a fragment of the RSV G gene was performed with nasopharyngeal aspirates (NPAs) collected from children with ARIs hospitalized in Chongqing Children's Hospital, Chongqing, China. A total of 1,387 NPA specimens were collected from April 2006 to March 2009, and 439 (31.7%) were positive for RSV. During the study period, subgroup A and B viruses accounted for 79.5% (349/439) and 19.8% (87/439) of the total positive samples, respectively. Both subgroup A and B viruses were identified in three samples. Subgroup A viruses were predominant during two epidemic seasons (2006 to 2008), while subgroup B strains prevailed during the 2008-2009 epidemic season. Phylogenetic analyses showed that all 30 group A strains could be clustered into one genotype, genotype GA2, and 30 group B strains could be clustered into three genotypes, genotypes GB1, GB3, and BA, among which 17 genotype BA strains were detected from 23 group B strains selected during the 2008-2009 epidemic season. The G gene of genotype BA was predicted to encode proteins of five different lengths. These data suggest that group A RSV likely predominated in southwestern China and that a new genotype of subgroup B with a 60-nucleotide insertion, named BA-like virus, became the dominant genotype in the 2008-2009 epidemic season.

Positive selection results in frequent reversible amino acid replacements in the G protein gene of human respiratory syncytial virus

Human respiratory syncytial virus (HRSV) is the major cause of lower respiratory tract infections in children under 5 years of age and the elderly, causing annual disease outbreaks during the fall and winter. Multiple lineages of the HRSVA and HRSVB serotypes co-circulate within a single outbreak and display a strongly temporal pattern of genetic variation, with a replacement of dominant genotypes occurring during consecutive years. In the present study we utilized phylogenetic methods to detect and map sites subject to adaptive evolution in the G protein of HRSVA and HRSVB. A total of 29 and 23 amino acid sites were found to be putatively positively selected in HRSVA and HRSVB, respectively. Several of these sites defined genotypes and lineages within genotypes in both groups, and correlated well with epitopes previously described in group A. Remarkably, 18 of these positively selected tended to revert in time to a previous codon state, producing a “flip-flop” phylogenetic pattern. Such frequent evolutionary reversals in HRSV are indicative of a combination of frequent positive selection, reflecting the changing immune status of the human population, and a limited repertoire of functionally viable amino acids at specific amino acid sites.

As part of the Viral Genetic Diversity Network (VGDN), we sequenced the second variable region (G2) of the G protein of human respiratory syncytial virus (HRSV) A and B from 568 patients sampled during 11 consecutive HRSV seasons (1995–2005) in the state of São Paulo, Brazil. A total of 933 HRSVA and 673 HRSB time-stamped sequences, including those sampled here and globally, was used for phylogenetic inference and the analysis of selection pressures. We identified 18 positively selected sites in both HRSVA (9 sites) and HRSVB (9 sites) that tended to revert in time to their previous codon state (i.e. exhibited a “flip-flop” pattern). We argue that these common evolutionary reversals are indicative of frequent positive selection, reflecting the changing immune status of the human population, coupled with a limited repertoire of functional viable amino acids at specific sites. This information is of particular importance since the ectodomain of the G protein is also a target site in vaccines that have so far proven unsuccessful and because it constitutes a significant step towards describing and understanding the immune-escape repertoire of this major human pathogen.

Outbreak of acute respiratory disease in China caused by B2 species of adenovirus type 11

An outbreak of acute respiratory tract infection occurred in Shanxi Province, China, from March to April 2006. Of the 254 patients affected by this outbreak, 247 patients were students of a senior high school; 1 of these patients died during the outbreak. Serological tests and blood culture revealed no evidence of bacterial infection. The results of direct reverse transcription-PCR or PCR performed with clinical specimens collected from the patients, including the sole patient who died, were positive for human adenoviruses (HAdVs) but negative for influenza virus, measles virus, rubella virus, mumps virus, parainfluenza virus, respiratory syncytial virus, and human enteroviruses. These findings were confirmed by enzyme-linked immunosorbent assay for HAdV immunoglobulin A, the conventional neutralization test, and viral isolation and identification. Sequencing of the entire hexon gene revealed that HdAV type 11a (HAdV-11a) belonging to the B2 species of HAdV was the etiological agent responsible for the outbreak. However, both the analysis of the phylogenetic relationship and the similarity plot indicated that the sequence of the 3' end of the hexon gene outside the hypervariable regions the HAdV-11a strain isolated in this outbreak may be a recombinant with the sequence of the HAdV-14 strain of species B2. Although isolates of HAdV species B2 seldom cause respiratory infections, they may pose a new global challenge with regard to acute respiratory diseases; this possibility cannot be overlooked and should be carefully considered. Hence, the need to establish and improve both epidemiological and virological surveillance of HAdV infections in China should be emphasized.

Genotyping of respiratory syncytial virus (RSV) group A in Stockholm, Sweden, using PCR and two-dimensional melting curve analysis

Genotyping of respiratory syncytial (RS) virus group A, by means of a novel method based on PCR, FRET (fluorescence resonance energy transmission) detection and two-dimensional melting curve analysis, was carried out on 80 RS virus samples of group A collected in Stockholm from 1976 to 2005. The Tm values were assessed for three different genotypes (GA2, GA5 and GA7) circulating in Sweden. Two pairs of probes were used and results of subsequent data analysis were plotted in a two-dimensional system. The results obtained were compared to genotyping using conventional nucleotide sequencing and phylogenetic tree analysis. It was found that the new assay was able to correctly identify genotype in about 89% of the isolates; it identified the remaining 11% as untypeable and as candidates for conventional nucleotide sequencing. The new method constitutes a complement to nucleotide sequencing and could be useful in studies of large numbers of samples in epidemiological studies.