Genetic diversity of human metapneumovirus over 4 consecutive years in Australia

Population-based incidence of human metapneumovirus infection among hospitalized children

Background. Human metapneumovirus (HMPV) is a leading cause of acute respiratory illness (ARI) in children. Population-based incidence rates and comprehensive clinical characterizations of disease have not been established.

Methods. We conducted population-based prospective surveillance for 2 years in 2 US counties of HMPV infection among children <5 years old who were hospitalized with ARI or fever. Nasal and throat specimens obtained with swabs were tested for HMPV by real-time reverse-transcription polymerase chain reaction and genotyped.

Results. Forty-two (3.8%) of 1104 children tested positive for HMPV. The overall annual rate of HMPVassociated hospitalizations per 1000 children <5 years old was 1.2 (95% confidence interval [CI], 0.9–1.6). This rate was highest among infants 0–5 months old (4.9 per 1000 [95% CI, 2.9–7.2]), followed by children 6–11 months old (2.9 per 1000 [95% CI, 1.4–4.7]). The annual rate of hospitalization for HMPV infection was less than that for respiratory syncytial virus infection but similar to that for influenza and parainfluenza virus 3 infection in all age groups. The mean age of children hospitalized with HMPV infection was 6 months. Bronchiolitis, pneumonia, and asthma were the most common diagnoses among children with HMPV infection. All 4 HMPV subgroups were detected during both years at both sites. HPMV infection was most prominent from March through May.

Conclusion. HMPV was detected in 3.8% of children hospitalized with ARI or fever, with a population incidence similar to that of influenza virus and parainfluenza virus 3.

Development and evaluation of a whole virus-based enzyme-linked immunosorbent assay for the detection of human metapneumovirus antibodies in human sera

To apply serological testing for human metapneumovirus (hMPV) to large-scale sera samples, an enzyme-linked immunosorbent assay (ELISA) was developed in which purified virions were used as the antigen. The ELISA was evaluated using 102 human sera specimens from patients aged 0-59 years. There was a positive association between the ELISA results and neutralization test titers, with the correlation coefficients being greater in children <6 years old (rho=0.899, P<0.0001), which is consistent with a primary infection, than in persons >or=6 years old (rho=0.523, P<0.0001). Fifty sera samples were subjected to radioimmunoprecipitation to measure the quantity of antibodies to the fusion protein (RIP-F) and the nucleoprotein (RIP-N). The results showed significant associations between the ELISA titers and the amount of RIP-F as determined by radioimmunoprecipitation in children <6 years old (rho=0.804, P=0.0083) and in persons >or=6 years old (rho=0.577, P=0.0009). The correlation between the ELISA titer and the amount of RIP-N determined by radioimmunoprecipitation was not significant in persons >or=6 years old (rho=0.417, P=0.0829), although this correlation was significant in children <6 years old (rho=0.764, P=0.0137). The ELISA titer correlated with the amount of antibodies to the F protein, but not to the N protein. This whole virus-based ELISA will be useful for the diagnosis of hMPV infection in clinical laboratories and is also useful for the large-scale investigations, such as seroprevalence among residents of a particular region.

Incidence, molecular epidemiology and clinical presentations of human metapneumovirus; assessment of its importance as a diagnostic screening target

BACKGROUND

Human metapneumovirus (HMPV) is a recently discovered human paramyxovirus associated with a spectrum of respiratory symptoms from the common cold to pneumonia and bronchiolitis.

OBJECTIVES

To assess the clinical significance and epidemiology of HMPV, standardized comparison of frequencies of infection, age profiles and disease associations were made with other respiratory viruses in Scotland.

STUDY DESIGN

7091 respiratory samples collected in Scotland between 1 July 2006 and 30 June 2008 from 4282 individuals were screened by multiplex RT-PCR for respiratory syncytial virus (HRSV), adenovirus (AdV), parainfluenza viruses 1-3 (PIV-1, -2 and -3), influenza A and B and by nested RT-PCR for HMPV.

RESULTS

HMPV was the fifth most prevalent virus (2.0% of samples), found predominantly in young children in winter months. In the 2006-2007 respiratory season, 70% of HMPV isolates were genotype A, but a switch to predominantly type B infections occurred next winter. For samples with information on clinical presentations, 26% of HMPV infections were from subjects with lower respiratory tract presentations, lower than recorded for HRSV, but similar to adenovirus, parainfluenza viruses and influenza viruses A and B. Around 13% of HMPV infections were associated with upper respiratory tract symptoms or disease, comparable with other respiratory virus infections.

CONCLUSIONS

Numerically and through its association with respiratory disease, HMPV represents a diagnostically significant target that should be included in PCR-based routine screening of respiratory samples. Understanding the biological basis of observed rapid turnover of HMPV variants, including the observed HMPV genotype change between respiratory seasons requires further longitudinal studies.

Genetic diversity and evolution of human metapneumovirus fusion protein over twenty years

BACKGROUND

Human metapneumovirus (HMPV) is an important cause of acute respiratory illness in children. We examined the diversity and molecular evolution of HMPV using 85 full-length F (fusion) gene sequences collected over a 20-year period.

RESULTS

The F gene sequences fell into two major groups, each with two subgroups, which exhibited a mean of 96% identity by predicted amino acid sequences. Amino acid identity within and between subgroups was higher than nucleotide identity, suggesting structural or functional constraints on F protein diversity. There was minimal progressive drift over time, and the genetic lineages were stable over the 20-year period. Several canonical amino acid differences discriminated between major subgroups, and polymorphic variations tended to cluster in discrete regions. The estimated rate of mutation was 7.12 x 10(-4) substitutions/site/year and the estimated time to most recent common HMPV ancestor was 97 years (95% likelihood range 66-194 years). Analysis suggested that HMPV diverged from avian metapneumovirus type C (AMPV-C) 269 years ago (95% likelihood range 106-382 years).

CONCLUSION

HMPV F protein remains conserved over decades. HMPV appears to have diverged from AMPV-C fairly recently.

Epidemiology and genetic variability of human metapneumovirus during a 4-year-long study in Southeastern Brazil

Epidemiological and molecular characteristics of human metapneumovirus (hMPV) were compared with human respiratory syncytial virus (hRSV) in infants and young children admitted for acute lower respiratory tract infections in a prospective study during four consecutive years in subtropical Brazil. GeneScan polymerase chain assays (GeneScan RT-PCR) were used to detect hMPV and hRSV in nasopharyngeal aspirates of 1,670 children during January 2003 to December 2006. hMPV and hRSV were detected, respectively, in 191 (11.4%) and in 702 (42%) of the children admitted with acute lower respiratory tract infections at the Sao Paulo University Hospital. Sequencing data of the hMPV F gene revealed that two groups of the virus, each divided into two subgroups, co-circulated during three consecutive years. It was also shown that a clear dominance of genotype B1 occurred during the years 2004 and 2005, followed by genotype A2 during 2006.

Review of new and newly discovered respiratory tract viruses in children

Respiratory tract viral infection continues to be among the most common reasons for emergency department visits and hospitalization of children, particularly infants younger than 1 year, in the United States. Throughout the years, clinicians have considered respiratory syncytial virus followed by influenza as the most common pathogens responsible. Over the past decade, new viruses have been discovered through both more specific testing and the finding of new agents causing infection. This includes human metapneumovirus, which leads to similar but often epidemiologically more severe clinical symptoms than respiratory syncytial virus. Other agents responsible for lower respiratory tract infection include Coronavirus (severe acute respiratory syndrome), Bocavirus, and others. This review serves to focus on some of the recent literature on these agents and the clinical impact they have on pediatric lung infection.

Epidemiology

The common cold is the result of an upper respiratory tract infection causing an acute syndrome characterised by a combination of non-specific symptoms, including sore throat, cough, fever, rhinorrhoea, malaise, headache, and myalgia. Respiratory viruses, alone or in combination, are the most common cause. The course f illness can be complicated by bacterial agents, causing pharyngitis or sinusitis, but the are a rare cause of cold and flu-like illnesses (CFLIs). Our understanding of CFLI epidemiology has been enhanced by molecular detection methods, particularly polymerase chain reaction (PCR) testing. PCR has not only improved detection of previously known viruses, but within the last decade has resulted in the detection of many divergent novel respiratory virus species. Human rhinovirus (HRV) infections cause nearly all CFLIs and they can be responsible for asthma and chronic obstructive pulmonary disease exacerbations. HRVs are co-detected with other respiratory viruses in statistically significant patterns, with HRVs occurring in the lowest proportion of co-detections, compared to most other respiratory viruses. Some recently identified rhinoviruses may populate an entirely new putative HRV species; HRV C. Further work is required to confirm a causal role for these newly identified viruses in CFLIs. The burden of illness associated with CFLIs is poorly documented, but where data are available, the impact of CFLIs is considerable. Individual infections, although they do not commonly result in more severe respiratory tract illness, are associated with substantial direct and indirect resource use. The product of frequency and burden for CFLIs is likely to be greater in magnitude than for any other respiratory syndrome, but further work is required to document this. Our understanding of the viral causes of CLFIs, although incomplete, has improved in recent years. Documenting burden is also an important step in progress towards improved control and management of these illnesses.

The incidence of human bocavirus infection among children admitted to hospital in Singapore

Human bocavirus (HBoV) is a parvovirus, belonging to the genus Bocavirus. The virus was identified recently in Sweden, and has now been detected in several different countries. Although it is associated with lower respiratory tract infections in pediatric patients, the incidence of HBoV infection in a developed country in South East Asia, has not been examined. The objective of this study was to determine the importance of HBoV as a cause of lower respiratory tract infections among children admitted to hospital in Singapore. Five hundred nasopharyngeal swabs were collected from anonymized pediatric patients admitted to the Kandang Kerbau Women's and Children's Hospital for acute respiratory infections. The specimens were tested for the presence of HBoV using polymerase chain reactions. HBoV was detected in 8.0% of the patients tested, and a majority of these HBoV patients exhibited lower respiratory tract infections. A significant level of coinfection with respiratory syncytial viruses and rhinoviruses was also observed in these HBoV patients. The data suggest that HBoV is an important cause of lower respiratory tract infections among children admitted to hospital in Singapore, and is the first study examining the incidence of HBoV infection in a developed country in South East Asia. J. Med. Virol. 81:82–89, 2009. © 2008 Wiley‐Liss, Inc.

Biennial spring activity of human metapneumovirus in Austria

BACKGROUND

Human metapneumovirus (HMPV) is considered an important respiratory pathogen in young children. To gain insight into the seasonality and epidemiologic characteristics of HMPV infection, this study determined the frequency of HMPV infections in hospitalized infants during a 7-year period.

METHODS

By use of real-time reverse-transcriptase polymerase chain reaction, nasopharyngeal aspirates from 1612 infants less than 2 years of age who were hospitalized for acute respiratory tract illness were tested for the presence of HMPV. Weekly HMPV testing data were analyzed to assess the timing of HMPV activity. Season variability was estimated by comparing the onset, duration, peak, and end of outbreaks from October 2000 through October 2007.

RESULTS

Overall, 109 (6.8%) of 1612 cases of acute respiratory illness were associated with HMPV infection. Seasonal HMPV activity varied substantially from year to year, both in prevalence rates of HMPV cases and in seasonal timing of outbreaks. HMPV activity was characterized by a biennial rhythm, with spring seasons occurring every second year, and these accounted for a substantial proportion, up to 30%, of hospitalized cases of acute respiratory tract illness.

CONCLUSIONS

HMPV activity varies substantially from year to year, both in the frequency and timing of illness and shows a biennial pattern of alternating winter and spring activity.

Detection of four genetic subgroup-specific antibodies to human metapneumovirus attachment (G) protein in human serum

Human metapneumovirus (hMPV) strains are classified into two genetic groups, A and B, each of which is further divided in two genetic subgroups, A1, A2, B1 and B2. hMPV encodes two major surface glycoproteins, the fusion (F) and attachment (G) proteins, which may be immunogenic and protective antigens. Although the amino acid sequences of hMPV F protein are highly conserved, those of the G protein are highly variable with low amino acid identity between the two groups. To address the antigenic variation between the genetic subgroups, we developed an immunofluorescence assay (IFA) method using Trichoplusia ni (Tn5) insect cells infected with each recombinant baculovirus-expressed hMPV G (Bac-G) protein of the four genetic subgroups. The titre of each antibody to the four Bac-G proteins was measured by the IFA in 12 paired serum samples obtained from children infected with hMPV of each genetic subgroup. Although 11 of the 12 acute-phase serum samples in paired samples were negative for the antibody to any Bac-G proteins, all of the convalescent-phase serum samples in those paired samples were positive for the antibody to only one of the four Bac-G proteins of the infecting genotype of hMPV. Since the antibody response to hMPV G protein was transient and genetic subgroup-specific without cross-reactivity, four genetic subgroups on the basis of hMPV G protein could be identified as different serotypes. This assay may be useful for the study of immune responses of humans to different hMPV strains, especially for clarifying the risk of reinfection with hMPV.

Inhibition of Human Metapneumovirus Replication by Small Interfering RNA

Background

Human metapneumovirus (hMPV) is a major respiratory viral pathogen in young children, elderly individuals and immunocompromised patients. Despite its major effects related to bronchiolitis, pneumonia and its potential role in recurrent wheezing episodes, there is still no commercial treatment or vaccine available against this paramyxovirus.

Methods

We tested a therapeutic strategy for hMPV that was based on RNA interference.

Results

An hMPV genome-wide search for small interfering RNAs (siRNAs) by computational analysis revealed 200 potentially effective 21-mer siRNAs. Initial screening with a luciferase assay identified 57 siRNAs of interest. Further evaluation of their inhibitory potential against the four hMPV subgroups by quantitative real-time reverse transcriptase PCR and plaque immunoassay identified two highly potent siRNAs with 50% inhibitory concentration (IC50) values in the subnanomolar range. siRNA45 targets the nucleoprotein messenger RNA (mRNA) and had IC50 values <0.078 nM against representative strains from the four hMPV subgroups, whereas siRNA60, which targets the phosphoprotein mRNA, had IC50 values between 0.090– <0.078 nM against the same panel of hMPV strains. Longer 25/27-mer siRNAs known as Dicer substrates designed from the top two siRNA candidates were also evaluated and were at least as effective as their corresponding 21-mer siRNAs. Interestingly, the presence of one or two nucleotide mismatches in the target mRNA sequence of some hMPV subgroups did not always affect hMPV inhibition in vitro.

Conclusions

We successfully identified two highly efficient siRNAs against hMPV targeting essential components of the hMPV replication complex.

The emergence of human metapneumovirus

Until relatively recently there had been episodes when children had been admitted into hospitals with symptoms that were similar to those expected for human respiratory syncytial virus (HRSV), but the available diagnostic procedures failed to detect the presence of HRSV, and the causative disease agent remained unidentified. Dutch scientists examined nasopharyngeal aspirates from similar patients in Holland using advanced molecular biology and imaging techniques. The conclusions of this study were published in 2001, revealing that a previously unidentified paramyxovirus was responsible for these infections. This agent was grouped within the subfamily Pneumovirinae, genus metapneumovirus, and given the name human metapneumovirus (HMPV) to distinguish it from other members of the genus Metapneumovirus that are of avian origin. Although HMPV is associated with upper respiratory tract infection, it is now recognized as a major cause of lower respiratory infection (LRTI) in children in a variety of different geographical regions. Furthermore, retrospective studies have detected the presence of HMPV in archived clinical material dating from the 1950s, suggesting that this was not a new virus, but it had remained undetected for several decades until its ‘emergence’ in 2001. This review will discuss the increasing global importance of HMPV as a cause of LRTI among young children.

Clinical impact of human metapneumovirus genotypes and genotype-specific seroprevalence in Yamagata, Japan

The clinical impact of human metapneumovirus (hMPV) genotypes and the relation between the hMPV genotype in circulation and genotype-specific seroprevalence are yet to be clarified. We determined the genotypes of 93 hMPV strains that were isolated between 2004 and 2006 in Yamagata, Japan, and identified 35 genotype A2, 14 genotype B1, and 44 genotype B2 isolates. Children infected with genotype A2 hMPV were significantly older than those infected with genotype B1 hMPV. Diagnosis of laryngitis was more common in children with genotype B1 hMPV infection and wheezing was more prevalent in children with genotype B1 and B2 hMPV infection than in those with genotype A2 hMPV infection. We then examined genotype-specific seroprevalence by neutralization assay. The higher seropositive rate for the B2 genotype among the children aged 1-2 years is likely to reflect the outbreak of B2 genotype strains in the previous year in this community. The low seropositive rate for the B1 genotype among children aged 1-2 years appears to be associated with a finding that more than 70% of children infected with the B1 genotype were less than 3 years old. In conclusion, we found that the different clinical characteristics of hMPV infection may be associated with hMPV genotype, and the predominant genotype during a season and the affecting age may be closely related to genotype-specific immune status within a community.

[Human metapneumovirus]

Le métapneumovirus humain (hMPV) est un nouveau Pneumovirinae apparenté au métapneumovirus aviaire du type C. Le génome du hMPV diffère de celui du virus respiratoire syncytial humain (RSV) par l’ordre des gènes et le manque des gènes non structuraux. Deux sous-groupes génétiques de hMPV et quatre sous-types ont été identifiés. Les infections à hMPV évoluent sous forme d’épidémies hivernales régulières, superposées à celle du RSV et d’importance à peu près égale d’une année sur l’autre. Chez les enfants hospitalisés à Caen, le hMPV est détecté dans 9,7 % des cas, après le RSV (37 %), les rhinovirus (18 %), les virus influenza (15,4 %), les adénovirus (9 %) et les virus parainfluenza (5 %). La plupart des infections à hMPV sont observées chez des enfants atteints de bronchiolites, mais par comparaison à l’infection à RSV, l’atteinte respiratoire basse et les signes de gravité sont moins fréquents. Le hMPV est très difficile à isoler en cultures des cellules. Le diagnostic a reposé jusqu’ici sur la détection moléculaire par RT–PCR. L’apparition récente des tests antigéniques permet de disposer aujourd’hui d’un test de diagnostic rapide, simple et économique.

Detection and characterisation of human metapneumovirus from children with acute respiratory symptoms in north-west England, UK

BACKGROUND

Human metapneumovirus (hMPV) causes a spectrum of respiratory disease ranging from trivial coryzal symptoms to fatal pneumonia, with a predilection for the very young, the immune suppressed and the frail elderly. Five distinct lineages of the virus genome have been described.

OBJECTIVES

To develop and evaluate a sensitive, real-time PCR (RT-PCR) assay capable of detecting all lineages of hMPV, suitable for use in a diagnostic laboratory.

STUDY DESIGN

An RT-PCR assay was developed using novel primers and dual-labelled minor-groove-binding (MGB) probes complementary to consensus sequences. The assay and two alternative assays were tested against external quality assurance (EQA) panels. 221 respiratory samples collected during 2003-2004 were screened using the new assay. hMPV positive samples were sequenced and phylogenetically analysed.

RESULTS

Three genetic lineages of hMPV were detected during 2003-2004. Incidence was low (2.3%) compared to previous years. All five lineages had been present in the same community within the past 3 years.

CONCLUSIONS

The new assay correctly identified more EQA samples, including those at greatest dilution, than the alternative assays and detected all five lineages. Seasonal circulation of hMPV in paediatric patients with acute respiratory symptoms is dynamic with respect to incidence and viral genotype.

Human metapneumovirus infection in young children hospitalized with acute respiratory tract disease: virologic and clinical features

BACKGROUND

Human metapneumovirus (hMPV) is an emerging virus associated with acute respiratory tract infections (ARIs) in young children.

OBJECTIVES

To evaluate virologic and clinical features of hMPV infection during 2 consecutive winter-spring seasons.

METHODS

Nasal washes were obtained from children younger than 5 years of age hospitalized for ARI. Specimens were tested for hMPV by reverse transcription-polymerase chain reaction. The hMPV F gene amplification products were sequenced, and phylogenetic trees were constructed.

RESULTS

A high incidence of hMPV infection (25.3%) was observed during the 2005-2006 winter-spring season, whereas a much lower rate of infection (4.7%) during the following season was found. Phylogenetic analysis revealed that, during the 2 seasons, 60.4% of the hMPV detected were A2a, 22.9% were A2b, 4.2% were B1, and 12.5% were B2. hMPV A1 strains were not detected in any tested specimen. Clinical diagnosis was bronchiolitis in 57.1%; pneumonia in 25%; and a upper respiratory tract illness in 17.8%. Bronchiolitis was more frequent in children less than 1 year of age (80%) than in children more than 1 year of age (30.8%) (P < 0.05). When hMPV was found frequently, the hMPV spread overlapped with that of respiratory syncytial virus (RSV) and hMPV/RSV coinfections were common events (19 of 39; 48.7%). hMPV/RSV-coinfected children developed pneumonia more frequently than hMPV-infected patients (57.9% versus 20%) but no differences in disease severity (gauged by duration of hospitalization and requirement of oxygen) were observed.

CONCLUSIONS

These results provide further evidence of the importance of hMPV as a pathogen associated with ARI in young children. Involvement of hMPV/RSV coinfection in cases of pneumonia is suspected.

A PCR-restriction fragment length polymorphism assay to genotype human metapneumovirus

Human metapneumovirus (hMPV) genotypes A and B show epidemiological and probably clinical differences. This report describes a fast and simple PCR-restriction fragment length polymorphism (PCR-RFLP) assay, involving digestion of the fusion protein gene with Tsp509I, that allows lineages A1, A2, B1 and B2 to be distinguished. The assay should help in elucidating the epidemiology of hMPV, and possibly in predicting the severity of clinical infection.

Community epidemiology of human metapneumovirus, human coronavirus NL63, and other respiratory viruses in healthy preschool-aged children using parent-collected specimens

OBJECTIVES

The purpose of this work was to assess the impact of recently described human metapneumovirus and human coronavirus NL63 compared with other respiratory viruses by using sensitive molecular techniques in a cohort of healthy preschool-aged children. We also aimed to assess the use of parent collection to obtain an adequate respiratory specimen from acutely unwell children in the community.

PATIENTS AND METHODS

The community epidemiology and burden of human metapneumovirus and other respiratory viruses (influenza A, influenza B, respiratory syncytial virus, parainfluenza viruses, adenoviruses, and picornaviruses) were examined in a cohort of 234 preschool-aged children from Melbourne, Australia, over a 12-month period by using polymerase chain reaction testing. Parents collected a daily symptom diary for the duration of the study and were taught to collect a combined nose-throat swab and complete an impact diary when the study child had an acute respiratory illness.

RESULTS

The average incidence of acute respiratory illness was 0.48 per child-month for the duration of the study, with a winter peak. Of 543 illnesses with > or = 1 specimen returned, 33 were positive for human metapneumovirus (6.1%) and 18 for human coronavirus NL63 (3.3%). Of all of the viruses for which we tested, human metapneumovirus and human coronavirus NL63 were most strongly linked to child care attendance, occurring in 82% and 78% of infected children, respectively. Picornaviruses were the most commonly identified virus group (269 [49.5%]). Influenza virus and adenovirus illnesses had the greatest impact, with fever in more than three quarters and requiring, on average, > 1 local doctor visit per illness.

CONCLUSIONS

Recently identified human metapneumovirus and human coronavirus NL63 are important pathogens in community-based illness in children, particularly in those who attend child care. Picornaviruses were detected in half of the nose-throat swabs collected during acute respiratory illness in children but resulted in milder illnesses; influenza and adenovirus caused the highest-impact illnesses. The use of parent-collected specimens should be considered for additional community-based epidemiologic studies and vaccine trials.

Prospective study of human metapneumovirus infection: diagnosis, typing and virus quantification in nasopharyngeal secretions from pediatric patients

STUDY DESIGN

During the winter-spring seasons 2004-2005 and 2005-2006, 965 nasopharyngeal aspirates from 871 patients were examined for human metapneumovirus (hMPV) by both monoclonal antibodies (MAbs) and reverse transcription (RT)-PCR.

RESULTS

Overall, 46 samples (4.8%) from 37 patients were positive for hMPV. Of these, 39 were positive by RT-PCR, and 35 by MAbs. Thus, using RT-PCR as a reference assay, the sensitivity, specificity, positive and negative predictive values of MAbs were 71.8%, 99.2%, 80.0% and 98.8%, respectively. Typing showed that concordant results were obtained in 32/46 (69.6%) strains (five untyped), whereas three strains were typed by MAbs only, and 11 by RT-PCR only. Finally, quantification of hMPV RNA allowed to correlate high viral load in nasopharyngeal secretions with acute respiratory symptoms in a group of 11 infants with acute lower respiratory tract infection examined upon admission and discharge from hospital, and a group of nine infants examined upon admission only. Conversely, hMPV etiology was questioned in a group of 14 infants with low viral load.

CONCLUSIONS

MAbs may represent an alternative to or a complement to RT-PCR for detection and typing of hMPV strains, while hMPV RNA quantification may help in associating viral load with clinical symptoms.

VII International Symposium on Respiratory Viral Infections

The VII International Symposium on Respiratory Viral Infections was a multidisciplinary forum for the presentation of recent advances in respiratory virus research with special emphasis on antiviral therapies and vaccine strategies. Topics covered in invited lectures included detection of novel respiratory viral pathogens and viral evolution, characterization of the 1918 pandemic virus, human metapneumovirus infections, human respiratory epithelial cultures for studying viral pathogenesis, the role of respiratory viruses in the pathogenesis of asthma, influenza-bacterial interactions, advances in generating vaccine candidates against global respiratory threats like avian influenza and SARS, antiviral resistance surveillance in influenza viruses, and a mini-symposium on advances in viral diagnostics. Other talks covered the live, attenuated intranasal influenza vaccine, monoclonals for respiratory syncytial virus (RSV), mechanisms of antiviral resistance in influenza B, and novel inhibitors for influenza, RSV and rhinovirus infections.

Human metapneumovirus, Australia, 2001-2004

We examined 10,025 respiratory samples collected for 4 years (2001-2004) and found a 7.1% average annual incidence of human metapneumovirus. The epidemic peak of infection was late winter to spring, and genotyping showed a change in predominant viral genotype in 3 of the 4 years.