Molecular evolution of the haemagglutinin-neuraminidase gene in human parainfluenza virus type 3 isolates from children with acute respiratory illness in Yamagata prefecture, Japan

Comparison of mutations in human parainfluenza viruses during passage in primary human bronchial/tracheal epithelial air-liquid interface cultures and cell lines

Human parainfluenza virus (HPIV) causes respiratory infections, which are exacerbated in children and older people. Correct evaluation of viral characteristics is essential for the study of countermeasures. However, adaptation of viruses to cultured cells during isolation or propagation might select laboratory passage-associated mutations that modify the characteristics of the virus. It was previously reported that adaptation of HPIV3, but not other HPIVs, was avoided in human airway epithelia. To examine the influence of laboratory passage on the genomes of HPIV1-HPIV4, we evaluated the occurrence of mutations after passage in primary human bronchial/tracheal epithelial cell air-liquid interface (HBTEC-ALI) culture and conventional cultured cells (Vero cells expressing the transmembrane protease, serine 2, and normal Vero cells). The occurrence of mutations was significantly lower in HBTEC-ALI than in conventional culture. In HBTEC-ALI culture, most of the mutations were silent or remained at low variant frequency, resulting in less impact on the viral consensus sequence. In contrast, passage in conventional culture induced or selected genetic mutations at high frequency with passage-associated unique substitutions. High mutagenesis of hemagglutinin-neuraminidase was commonly observed in all four HPIVs, and mutations even occurred in a single passage. In addition, in HPIV1 and HPIV2, mutations in the large protein were more frequent. These results indicate that passage in HBTEC-ALI culture is more suitable than conventional culture for maintaining the original characteristics of clinical isolates in all four HPIVs, which can help with the understanding of viral pathogenesis.

IMPORTANCE

Adaptation of viruses to cultured cells can increase the risk of misinterpretation in virological characterization of clinical isolates. In human parainfluenza virus (HPIV) 3, it has been reported that the human airway epithelial and lung organoid models are preferable for the study of viral characteristics of clinical strains without mutations. Therefore, we analyzed clinical isolates of all four HPIVs for the occurrence of mutations after five laboratory passages in human bronchial/tracheal epithelial cell air-liquid interface (HBTEC-ALI) or conventional culture. We found a high risk of hemagglutinin-neuraminidase mutagenesis in all four HPIVs in conventional cultured cells. In addition, in HPIV1 and HPIV2, mutations of the large protein were also more frequent in conventional cultured cells than in HBTEC-ALI culture. HBTEC-ALI culture was useful for maintaining the original sequence and characteristics of clinical isolates in all four HPIVs. The present study contributes to the understanding of HPIV pathogenesis and antiviral strategies.

Human Parainfluenza Virus (HPIV) Detection in Hospitalized Children with Acute Respiratory Tract Infection in the Western Cape, South Africa during 2014-2022 Reveals a Shift in Dominance of HPIV 3 and 4 Infections

The epidemiology of human parainfluenza viruses (HPIV), particularly its role as a cause of acute respiratory infection (ARI) in infants, has not been formally studied in South Africa. We evaluated HPIV prevalence in diagnostic samples from hospitalized children from public sector hospitals in the Western Cape between 2014 and 2022. HPIV infection was detected in 2-10% of patients, with the majority of infections detected in children less than 1 year of age. Prior to 2020, HPIV 4 (40%) and HPIV 3 (34%) were the most prevalent types, with seasonal peaks in late winter/spring for HPIV 3 and autumn/winter for HPIV 4. HPIV 4A and 4B co-circulated during the seasonal activity between 2014 and 2017. Pandemic restrictions in 2020 had a profound effect on HPIV circulation and the rebound was dominated by waves of HPIV 3, accounting for 66% of detections and a sustained decline in the circulation of HPIV 1, 2 and 4. An immunity gap could account for the surge in HPIV 3 infections, but the decline in prior HPIV 4 dominance is unexplained and requires further study.

Molecular evolutionary analyses of the fusion protein gene in human respirovirus 1

Few evolutionary studies of the human respiratory virus (HRV) have been conducted, but most of them have focused on HRV3. In this study, the full-length fusion (F) genes in HRV1 strains collected from various countries were subjected to time-scaled phylogenetic, genome population size, and selective pressure analyses. Antigenicity analysis was performed on the F protein. The time-scaled phylogenetic tree using the Bayesian Markov Chain Monte Carlo method estimated that the common ancestor of the HRV1 F gene diverged in 1957 and eventually formed three lineages. Phylodynamic analyses showed that the genome population size of the F gene has doubled over approximately 80 years. Phylogenetic distances between the strains were short (< 0.02). No positive selection sites were detected for the F protein, whereas many negative selection sites were identified. Almost all conformational epitopes of the F protein, except one in each monomer, did not correspond to the neutralising antibody (NT-Ab) binding sites. These results suggest that the HRV1 F gene has constantly evolved over many years, infecting humans, while the gene may be relatively conserved. Mismatches between computationally predicted epitopes and NT-Ab binding sites may be partially responsible for HRV1 reinfection and other viruses such as HRV3 and respiratory syncytial virus.

Virological Surveillance and Molecular Characterization of Human Parainfluenzavirus Infection in Children with Acute Respiratory Illness: Germany, 2015-2019

Human parainfluenza viruses (HPIVs) are important causes of respiratory illness, especially in young children. However, surveillance for HPIV is rarely performed continuously, and national-level epidemiologic and genetic data are scarce. Within the German sentinel system, to monitor acute respiratory infections (ARI), 4463 respiratory specimens collected from outpatients < 5 years of age between October 2015 and September 2019 were retrospectively screened for HPIV 1-4 using real-time PCR. HPIV was identified in 459 (10%) samples. HPIV-3 was the most common HPIV-type, with 234 detections, followed by HPIV-1 (113), HPIV-4 (61), and HPIV-2 (49). HPIV-3 was more frequently associated with age < 2 years, and HPIV-4 was more frequently associated with pneumonia compared to other HPIV types. HPIV circulation displayed distinct seasonal patterns, which appeared to vary by type. Phylogenetic characterization clustered HPIV-1 in Clades 2 and 3. Reclassification was performed for HPIV-2, provisionally assigning two distinct HPIV-2 groups and six clades, with German HPIV-2s clustering in Clade 2.4. HPIV-3 clustered in C1, C3, C5, and, interestingly, in A. HPIV-4 clustered in Clades 2.1 and 2.2. The results of this study may serve to inform future approaches to diagnose and prevent HPIV infections, which contribute substantially to ARI in young children in Germany.

Genetic diversity and evolutionary analysis of human respirovirus type 3 strains isolated in Kenya using complete hemagglutinin-neuraminidase (HN) gene

Human respirovirus type 3 (HRV3) is a leading etiology of lower respiratory tract infections in young children and ranks only second to the human respiratory syncytial virus (HRSV). Despite the public health importance of HRV3, there is limited information about the genetic characteristics and diversity of these viruses in Kenya. To begin to address this gap, we analyzed 35 complete hemagglutinin-neuraminidase (HN) sequences of HRV3 strains isolated in Kenya between 2010 and 2013. Viral RNA was extracted from the isolates, and the entire HN gene amplified by RT-PCR followed by nucleotide sequencing. Phylogenetic analyses of the sequences revealed that all the Kenyan isolates grouped into genetic Cluster C; sub-clusters C1a, C2, and C3a. The majority (54%) of isolates belonged to sub-cluster C3a, followed by C2 (43%) and C1a (2.9%). Sequence analysis revealed high identities between the Kenyan isolates and the HRV3 prototype strain both at the amino acid (96.5-97.9%) and nucleotide (94.3-95.6%) levels. No amino acid variations affecting the catalytic/active sites of the HN glycoprotein were observed among the Kenyan isolates. Selection pressure analyses showed that the HN glycoprotein was evolving under positive selection. Evolutionary analyses revealed that the mean TMRCA for the HN sequence dataset was 1942 (95% HPD: 1928-1957), while the mean evolutionary rate was 4.65x10-4 nucleotide substitutions/site/year (95% HPD: 2.99x10-4 to 6.35x10-4). Overall, our results demonstrate the co-circulation of strains of cluster C HRV3 variants in Kenya during the study period. This is the first study to describe the genetic and molecular evolutionary aspects of HRV3 in Kenya using the complete HN gene.

Molecular evolution of the hemagglutinin-neuraminidase (HN) gene in human respirovirus 3

Human respirovirus 3 (HRV3) is a major causative agent of acute respiratory infections in humans. HRV3 can manifest as a recurrent infection, although exactly how is not known. In the present study, we conducted detailed molecular evolutionary analyses of the major antigen-coding hemagglutinin-neuraminidase (HN) gene of this virus detected/isolated in various countries. We performed analyses of time-scaled evolution, similarity, selective pressure, phylodynamics, and conformational epitope prediction by mapping to HN protein models. In this way, we estimated that a common ancestor of the HN gene of HRV3 and bovine respirovirus 3 diverged around 1815 and formed many lineages in the phylogenetic tree. The evolutionary rates of the HN gene were 1.1 × 10^-3 substitutions/site/year, although the majority of these substitutions were synonymous. Some positive and many negative selection sites were predicted in the HN protein. Phylodynamic fluctuations of the gene were observed, and these were different in each lineage. Furthermore, most of the predicted B cell epitopes did not correspond to the neutralization-related mouse monoclonal antibody binding sites. The lack of a link between the conformational epitopes and neutralization sites may explain the naturally occurring HRV3 reinfection.

Sequencing and analysis of globally obtained human parainfluenza viruses 1 and 3 genomes

Human Parainfluenza viruses (HPIV) type 1 and 3 are important causes of respiratory tract infections in young children globally. HPIV infections do not confer complete protective immunity so reinfections occur throughout life. Since no effective vaccine is available for the two virus subtypes, comprehensive understanding of HPIV-1 and HPIV-3 genetic and epidemic features is important for diagnosis, prevention, and treatment of HPIV-1 and HPIV-3 infections. Relatively few whole genome sequences are available for both HPIV-1 and HPIV-3 viruses, so our study sought to provide whole genome sequences from multiple countries to further the understanding of the global diversity of HPIV at a whole-genome level. We collected HPIV-1 and HPIV-3 samples and isolates from Argentina, Australia, France, Mexico, South Africa, Switzerland, and USA from the years 2003-2011 and sequenced the genomes of 40 HPIV-1 and 75 HPIV-3 viruses with Sanger and next-generation sequencing with the Ion Torrent, Illumina, and 454 platforms. Phylogenetic analysis showed that the HPIV-1 genome is evolving at an estimated rate of 4.97 × 10-4 mutations/site/year (95% highest posterior density 4.55 × 10-4 to 5.38 × 10-4) and the HPIV-3 genome is evolving at a similar rate (3.59 × 10-4 mutations/site/year, 95% highest posterior density 3.26 × 10-4 to 3.94 × 10-4). There were multiple genetically distinct lineages of both HPIV-1 and 3 circulating on a global scale. Further surveillance and whole-genome sequencing are greatly needed to better understand the spatial dynamics of these important respiratory viruses in humans.

Longitudinal Epidemiology of Viral Infectious Diseases Combining Virus Isolation, Antigenic Analysis, and Phylogenetic Analysis as Well as Seroepidemiology in Yamagata, Japan, between 1999 and 2018

We introduced a microplate method for virus isolation in the Department of Microbiology, Yamagata Prefectural Institute of Public Health (YPIPH) in 1999 in Yamagata, Japan. We have since carried out longitudinal epidemiological studies on viral infectious diseases, particularly respiratory viruses, combining traditional technologies such as virus isolation and serological techniques and newly developed molecular methods. Here, we provide an overview of our activities at YPIPH between 1999 and 2018. During the study period, we observed emerging and re-merging diseases such as those caused by echovirus type 13, enterovirus D68, parechovirus-A3 (PeV-A3), and Saffold virus. With regard to PeV-A3, we proposed a new disease concept, "PeV-A3-associated myalgia/myositis." We also revealed the longitudinal epidemiologies of several viruses such as enterovirus A71 and coxsackievirus A16. To perform longitudinal epidemiological studies at any time in Yamagata, we established a system for stocking clinical specimens, viral isolates, complementary DNAs, and serum specimens. We have also pursued collaboration works with virology laboratories across Japan. We hope our experiences, findings, and research materials will further contribute to the development of countermeasures against viral infectious diseases and improvement in public health strategies in Yamagata, Japan, Asia, and around the world.

UK circulating strains of human parainfluenza 3: an amplicon based next generation sequencing method and phylogenetic analysis

Background: Human parainfluenza viruses type 3 (HPIV3) are a prominent cause of respiratory infection with a significant impact in both pediatric and transplant patient cohorts.  Currently there is a paucity of whole genome sequence data that would allow for detailed epidemiological and phylogenetic analysis of circulating strains in the UK. Although it is known that HPIV3 peaks annually in the UK, to date there are no whole genome sequences of HPIV3 UK strains available.  Methods: Clinical strains were obtained from HPIV3 positive respiratory patient samples collected between 2011 and 2015.  These were then amplified using an amplicon based method, sequenced on the Illumina platform and assembled using a new robust bioinformatics pipeline. Phylogenetic analysis was carried out in the context of other epidemiological studies and whole genome sequence data currently available with stringent exclusion of significantly culture-adapted strains of HPIV3. Results: In the current paper we have presented twenty full genome sequences of UK circulating strains of HPIV3 and a detailed phylogenetic analysis thereof.  We have analysed the variability along the HPIV3 genome and identified a short hypervariable region in the non-coding segment between the M (matrix) and F (fusion) genes. The epidemiological classifications obtained by using this region and whole genome data were then compared and found to be identical. Conclusions: The majority of HPIV3 strains were observed at different geographical locations and with a wide temporal spread, reflecting the global distribution of HPIV3. Consistent with previous data, a particular subcluster or strain was not identified as specific to the UK, suggesting that a number of genetically diverse strains circulate at any one time. A small hypervariable region in the HPIV3 genome was identified and it was shown that, in the absence of full genome data, this region could be used for epidemiological surveillance of HPIV3.

Characterization of human parainfluenza virus-3 circulating in Israel, 2012-2015

BACKGROUND

Human parainfluenza virus 3 (hPIV-3) causes respiratory tract infection.

OBJECTIVES

The objective of this study was to describe the epidemiology of hPIV-3 infection among hospitalized patients and characterize the circulating strains.

STUDY DESIGN

A cross-sectional study was conducted using respiratory samples of 15,946 hospitalized patients with respiratory symptoms in 2012-2015 in Israel. All samples were subjected to q-PCR and q-RT-PCR to determine the presence of hPIV-3 and other respiratory viruses. Samples positive for hPIV-3 were subjected to molecular typing and phylogenetic analysis.

RESULTS

Overall, 547 samples 3.4% (95% CI 3.2-3.7) were positive for hPIV-3. Of these 87 (15.9%) were mixed infections; 41.4% with adenovirus, 40.2% with RSV (40.2%) and 19.5% influenza A viruses. The prevalence of hPIV-3 was highest (5.1%) in children aged 0-4 years. Hospitalization in oncology department was associated with increased likelihood of hPIV-3 infection: adjusted odds ratio [aOR] 2.29 (95% confidence intervals [CI] 1.78-2.96), as well as hospitalization in organ transplantation department: aOR 3.65 (95% CI 2.80-4.76). The predominant lineages were C3c (62.3%) and C1b (24.6%), followed by sub-lineages C5 (8.7%) and C3b (2.9%). A new sub-lineage emerged in our analysis, named C1d, which was 17 (1.5%) nucleotide different from C1a, 25 (2.2%) nucleotide different from C1b and 24 (2.1%) nucleotide different from C1c.

DISCUSSION

Young children and immunocompromised patients are likely the risk groups for severe respiratory infections with hPIV-3. Strains belonging to lineages C3c and C1b, which are present worldwide, should be targeted in vaccine development. The emergence of new lineage might have public health implications and on vaccine development.

Human parainfluenza virus infection in severe acute respiratory infection cases in Beijing, 2014-2016: A molecular epidemiological study

Background

Severe acute respiratory infection (SARI) threatens human health and even survival, causing a huge number of hospitalized patients every year. However, as one of the most common respiratory viruses circulated worldwide, the epidemiological and phylogenetic characteristics of human parainfluenza virus (HPIV) in these cases were not well known.

Objectives

To reveal the epidemiological features of HPIV infection in SARIs in Beijing area from September 2014 to August 2016.

Methods

A total of 1229 SARI cases in Beijing area were enrolled, investigated, sampled, and tested by multiplex real‐time PCR to identify HPIVs and other common respiratory viruses. Eighteen HPIV‐3 viruses isolated from all HPIV‐positive samples in these SARI cases were sequenced and analyzed.

Results

Among all enrolled cases, 0.81%, 0.73%, 4.48%, and 0.57% were positive for HPIV‐1 to HPIV‐4, respectively. The highest yield rate of HPIV infection occurred in children under 5 years old (9.07%), followed by the patients over 60 years old (6.02%). The phylogenetic information of HPIV‐3 showed that all viruses belonged to Cluster C3a.

Conclusions

Besides the young children, the elders older than 60 years also showed a relatively high infection rate of HPIVs, which should be given comparable attentions. Moreover, the HPIV‐3 circulating in China undergoes continued evolution, suggesting the potential risk of evolved HPIV infection should not be overlooked.

Viral Entry Properties Required for Fitness in Humans Are Lost through Rapid Genomic Change during Viral Isolation

Human parainfluenza viruses cause a large burden of human respiratory illness. While much research relies upon viruses grown in cultured immortalized cells, human parainfluenza virus 3 (HPIV-3) evolves in culture. Cultured viruses differ in their properties compared to clinical strains. We present a genome-wide survey of HPIV-3 adaptations to culture using metagenomic next-generation sequencing of matched pairs of clinical samples and primary culture isolates (zero passage virus). Nonsynonymous changes arose during primary viral isolation, almost entirely in the genes encoding the two surface glycoproteins-the receptor binding protein hemagglutinin-neuraminidase (HN) or the fusion protein (F). We recovered genomes from 95 HPIV-3 primary culture isolates and 23 HPIV-3 strains directly from clinical samples. HN mutations arising during primary viral isolation resulted in substitutions at HN's dimerization/F-interaction site, a site critical for activation of viral fusion. Alterations in HN dimer interface residues known to favor infection in culture occurred within 4 days (H552 and N556). A novel cluster of residues at a different face of the HN dimer interface emerged (P241 and R242) and imply a role in HPIV-3-mediated fusion. Functional characterization of these culture-associated HN mutations in a clinical isolate background revealed acquisition of the fusogenic phenotype associated with cultured HPIV-3; the HN-F complex showed enhanced fusion and decreased receptor-cleaving activity. These results utilize a method for identifying genome-wide changes associated with brief adaptation to culture to highlight the notion that even brief exposure to immortalized cells may affect key viral properties and underscore the balance of features of the HN-F complex required for fitness by circulating viruses.IMPORTANCE Human parainfluenza virus 3 is an important cause of morbidity and mortality among infants, the immunocompromised, and the elderly. Using deep genomic sequencing of HPIV-3-positive clinical material and its subsequent viral isolate, we discover a number of known and novel coding mutations in the main HPIV-3 attachment protein HN during brief exposure to immortalized cells. These mutations significantly alter function of the fusion complex, increasing fusion promotion by HN as well as generally decreasing neuraminidase activity and increasing HN-receptor engagement. These results show that viruses may evolve rapidly in culture even during primary isolation of the virus and before the first passage and reveal features of fitness for humans that are obscured by rapid adaptation to laboratory conditions.

Detailed genetic analyses of the HN gene in human respirovirus 3 detected in children with acute respiratory illness in the Iwate Prefecture, Japan

We performed detailed genetic analyses of the partial hemagglutinin-neuraminidase (HN) gene in 34 human respirovirus 3 (HRV3) strains from children with acute respiratory illness during 2013-2015 in Iwate Prefecture, Japan. In addition, we performed analyses of the evolutionary timescale of the gene using the Bayesian Markov chain Monte Carlo (MCMC) method. Furthermore, we analyzed pairwise distances and performed selective pressure analyses followed by linear B-cell epitope mapping and N-glycosylation and phylodynamic analyses. A phylogenetic tree showed that the strains diversified at around 1939, and the rate of molecular evolution was 7.6 × 10^-4 substitutions/site/year. Although the pairwise distances were relatively short (0.03 ± 0.018 [mean ± standard deviation, SD]), two positive selection sites (Cys544Trp and Leu555Ser) and no amino acid substitutions were found in the active/catalytic sites. Six epitopes were estimated in this study, and three mouse monoclonal antibody binding sites (amino acid positions 278, 281, and 461) overlapped with two epitopes belonging to subcluster C3 strains. Bayesian skyline plot analyses indicated that subcluster C3 strains have been increasing from 2004, whereas subcluster C1 strains have declined from 2004. Based on these results, Iwate strains were divided into two subclusters and each subcluster evolved independently. Moreover, our results suggested that some predicted linear epitopes (epitopes 3 and 5) are candidates for an HRV3 vaccine motif. To better understand the details of the molecular evolution of HRV, further studies are needed.

Genetic analysis of human parainfluenza virus type 3 obtained in Croatia, 2011-2015

PURPOSE

This study investigated the HPIV3 circulating strains in Croatia and whether the other parts of HPIV3 genome (F gene and HN 582 nucleotides fragment) could be equally suitable for genetic and phylogenetic analysis.

METHODOLOGY

Clinical materials were collected in period 2011-2015 from children suffering from respiratory illnesses. In positive HPIV3 samples viral genome was partially amplified and sequenced for HN and F genes. Obtained sequences were analysed by phylogenetic analysis and genetic characterization was performed.

RESULTS

All samples from this study belonged to subcluster C and over a short period of time, genetic lineage C3a gained prevalence over the other C genetic lineages, from 39 % in 2011 to more than 90 % in 2013 and 2014. Phylogenetic classifications of HPIV3 based on the entire HN gene, HN 582 nt fragment and entire fusion (F) gene showed identical classification results for Croatian strains and the reference strains. Molecular analysis of the F and HN glycoproteins, showed their similar nucleotide diversity (Fcds P=0.0244 and HNcds P=0.0231) and similar Ka/Ks ratios (F Ka/Ks=0.0553 and HN Ka/Ks=0.0428). Potential N-glycosylation sites, cysteine residues and antigenic sites are generally strongly conserved in HPIV3 glycoproteins from both our and the reference samples.

CONCLUSION

The HPIV3 subclaster C3 (genetic lineage C3a) became the most detected circulating HPIV3 strain in Croatia. The results indicated that the HN 582 nt and the entire F gene sequences were as good for phylogenetic analysis as the entire HN gene sequence.

Genetic analyses of the fusion protein genes in human parainfluenza virus types 1 and 3 among patients with acute respiratory infections in Eastern Japan from 2011 to 2015

PURPOSE

To genetically explore the fusion protein gene (F) in human parainfluenza virus type 1 (HPIV1) and type 3 (HPIV3) strains, we analysed them in patients with acute respiratory infections in Eastern Japan from 2011 to 2015.

METHODOLOGY

We constructed phylogenetic trees based on the HPIV and HPIV3 F gene using the maximum likelihood method and conducted P-distance and selective pressure analyses. We also predicted the linear epitopes of the protein in the prototype strains. Furthermore, we mapped the amino acid substitutions of the proteins.

RESULTS

Nineteen strains of HPIV1 and 53 strains of HPIV3 were detected among the clinical acute respiratory infection cases. The phylogenetic trees indicated that the HPIV1 and HPIV3 strains were classified into clusters II and III and cluster C, respectively. The P-distance values of the HPIV1 and HPIV3 F genes were <0.03. Two positive selection sites were inferred in the HPIV1 (aa 8 and aa 10), and one positive selection site was inferred in the HPIV3 (aa 108), but over 10 negative selection sites were inferred. Four epitopes were predicted for the HPIV1 prototype strains, while five epitopes were predicted for the HPIV3 prototype strain. A positive selection site (aa 108) or the HPIV3 F protein was involved in the predicted epitope. Additionally, we found that an amino acid substitution (R73K) in the LC76627 HPIV3 strain presumably may affect the resistance to neutralization by antibodies.

CONCLUSION

The F gene of HPIV1 and HPIV3 was relatively well conserved in the eastern part of Japan during the investigation period.

Rapid Metagenomic Next-Generation Sequencing during an Investigation of Hospital-Acquired Human Parainfluenza Virus 3 Infections

Metagenomic next-generation sequencing (mNGS) is increasingly used for the unbiased detection of viruses, bacteria, fungi, and eukaryotic parasites in clinical samples. Whole-genome sequencing (WGS) of clinical bacterial isolates has been shown to inform hospital infection prevention practices, but this technology has not been utilized during potential respiratory virus outbreaks. Here, we report on the use of mNGS to inform the real-time infection prevention response to a cluster of hospital-acquired human parainfluenza 3 virus (HPIV3) infections at a children's hospital. Samples from 3 patients with hospital-acquired HPIV3 identified over a 12-day period on a general medical unit and 10 temporally associated samples from patients with community-acquired HPIV3 were analyzed. Our sample-to-sequencer time was <24 h, while our sample-to-answer turnaround time was <60 h with a hands-on time of approximately 6 h. Eight (2 cases and 6 controls) of 13 samples had sufficient sequencing coverage to yield the whole genome for HPIV3, while 10 (2 cases and 8 controls) of 13 samples gave partial genomes and all 13 samples had >1 read for HPIV3. Phylogenetic clustering revealed the presence of identical HPIV3 genomic sequence in the two of the cases with hospital-acquired infection, consistent with the concern for recent transmission within the medical unit. Adequate sequence coverage was not recovered for the third case. This work demonstrates the promise of mNGS for providing rapid information for infection prevention in addition to microbial detection.

Parainfluenza Virus Types 1, 2, and 3 in Pediatric Patients with Acute Respiratory Infections in Beijing During 2004 to 2012

BACKGROUND

Although human parainfluenza virus (HPIV) has been determined as an important viral cause of acute respiratory infections (ARIs) in infants and young children, data on long-term investigation are still lacking to disclose the infection pattern of HPIV in China.

METHODS

Nasopharyngeal aspirates were collected from 25,773 hospitalized pediatric patients with ARIs from January 2004 through December 2012 for respiratory virus screen by direct immuno-fluorescence assay.

RESULTS

Out of these specimens, 1675 (6.50%, 1675/25,773) showed HPIV positive, including 261 (1.01%, 261/25,773) for HPIV1, 28 (0.11%, 28/25,773) for HPIV2, and 1388 (5.39%, 1388/25,773) for HPIV3, 2 of the samples were positive for both HPIV1 and HPIV3, and 36 were co-detected with other viruses. The positive rates of HPIVs were higher in those younger than 3 years old. HPIV3 was detected from all age groups, predominantly from patients under 3 years of age, and the highest frequency was found in those 6 months to 1-year old (352/4077, 8.63%). HPIV3 was the dominant type in each of the years detected between May and July. HPIV1 showed a peak in every odd year, mainly in August or September. HPIV was detected most frequently from patients with upper respiratory infection (12.49%, 157/1257), followed by bronchitis (11.13%, 176/2479), asthma (9.31%, 43/462), bronchiolitis (5.91%, 150/2536), pneumonia (6.06%, 1034/17,068), and those with underlying diseases (1.0%, 15/1506). HPIV3 is the dominant type in these six disease groups referred above, especially in the asthma group.

CONCLUSIONS

HPIV is one of the important viral causes of ARIs in infants and young children in Beijing based on the data from the hospitalized children covering a 9-year term. HPIV3 is the predominant type in all these years and in most of the disease groups. HPIVs with different types show different seasonality.

Human parainfluenza virus-3 can be targeted by rapidly ex vivo expanded T lymphocytes

BACKGROUND AIMS

Human parainfluenza virus-3 (HPIV) is a common cause of respiratory infection in immunocompromised patients and currently has no effective therapies. Virus-specific T-cell therapy has been successful for the treatment or prevention of viral infections in immunocompromised patients but requires determination of T-cell antigens on targeted viruses.

METHODS

HPIV3-specific T cells were expanded from peripheral blood of healthy donors using a rapid generation protocol targeting four HPIV3 proteins. Immunophenotyping was performed by flow cytometry. Viral specificity was determined by interferon (IFN)-γ ELISpot, intracellular cytokine staining and cytokine measurements from culture supernatants by Luminex assay. Cytotoxic activity was tested by ⁵¹Cr release and CD107a mobilization assays. Virus-specific T cells targeting six viruses were then produced by rapid protocol, and the phenotype of HPIV3-specific T cells was determined by immunomagnetic sorting for IFN-γ-producing cells.

RESULTS

HPIV3-specific T cells were expanded from 13 healthy donors. HPIV3-specific T cells showed a CD4⁺ predominance (mean CD4:CD8 ratio 2.89) and demonstrated specificity for multiple HPIV3 antigens. The expanded T cells were polyfunctional based on cytokine production but only had a minor cytotoxic component. T cells targeting six viruses in a single product similarly showed HPIV3 specificity, with a predominant effector memory phenotype (CD3⁺/CD45RA^-/CCR7^-) in responder cells.

DISCUSSION

HPIV3-specific T cells can be produced using a rapid ex vivo protocol from healthy donors and are predominantly CD4⁺ T cells with Th1 activity. HPIV3 epitopes can also be successfully targeted alongside multiple other viral epitopes in production of six-virus T cells, without loss of HPIV3 specificity. These products may be clinically beneficial to combat HPIV3 infections by adoptive T-cell therapy in immune-compromised patients.

A molecular epidemiological study of human parainfluenza virus type 3 at a tertiary university hospital during 2013-2015 in Catalonia, Spain

Human parainfluenza virus type 3 (HPIV-3) is one of the most common respiratory viruses particularly among young children and immunocompromised patients. The seasonality, prevalence and genetic diversity of HPIV-3 at a Spanish tertiary-hospital from 2013 to 2015 are reported. HPIV-3 infection was laboratory-confirmed in 102 patients (76%, under 5 years of age). Among <5 years-old patients, 9 (11.5%) were under any degree of immunosuppression, whereas this percentage was significantly higher (19; 79.2%) among patients older than 5 years. HPIV-3 was detected at varying levels, but mainly during spring and summer. All characterized HN/F sequences fell within C1b, C5 and in other two closely C3a-related groups. Furthermore, a new genetic lineage (C1c) was described. Genetic similarity and epidemiological data confirmed some nosocomial infections, highlighting the importance of the HPIV-3 surveillance, particularly in high-risk patients. This study provides valuable information on HPIV-3 diversity due to the scarce information in Europe.

•

Children and immunosuppressed adults showed a great susceptibility to infection.

•

Valuable information about the current genetic diversity in Europe is provided.

•

Different lineages, including a first described, were locally circulating.

•

Genetic similarity and epidemiological data confirmed some nosocomial infections.

•

The present study highlights the importance of the HPIV-3 surveillance.

Constraints on the Genetic and Antigenic Variability of Measles Virus

Antigenic drift and genetic variation are significantly constrained in measles virus (MeV). Genetic stability of MeV is exceptionally high, both in the lab and in the field, and few regions of the genome allow for rapid genetic change. The regions of the genome that are more tolerant of mutations (i.e., the untranslated regions and certain domains within the N, C, V, P, and M proteins) indicate genetic plasticity or structural flexibility in the encoded proteins. Our analysis reveals that strong constraints in the envelope proteins (F and H) allow for a single serotype despite known antigenic differences among its 24 genotypes. This review describes some of the many variables that limit the evolutionary rate of MeV. The high genomic stability of MeV appears to be a shared property of the Paramyxovirinae, suggesting a common mechanism that biologically restricts the rate of mutation.

Features of Circulating Parainfluenza Virus Required for Growth in Human Airway

Respiratory paramyxoviruses, including the highly prevalent human parainfluenza viruses, cause the majority of childhood croup, bronchiolitis, and pneumonia, yet there are currently no vaccines or effective treatments. Paramyxovirus research has relied on the study of laboratory-adapted strains of virus in immortalized cultured cell lines. We show that findings made in such systems about the receptor interaction and viral fusion requirements for entry and fitness—mediated by the receptor binding protein and the fusion protein—can be drastically different from the requirements for infection in vivo. Here we carried out whole-genome sequencing and genomic analysis of circulating human parainfluenza virus field strains to define functional and structural properties of proteins of circulating strains and to identify the genetic basis for properties that confer fitness in the field. The analysis of clinical strains suggests that the receptor binding-fusion molecule pairs of circulating viruses maintain a balance of properties that result in an inverse correlation between fusion in cultured cells and growth in vivo. Future analysis of entry mechanisms and inhibitory strategies for paramyxoviruses will benefit from considering the properties of viruses that are fit to infect humans, since a focus on viruses that have adapted to laboratory work provides a distinctly different picture of the requirements for the entry step of infection.

Mechanistic information about viral infection—information that impacts antiviral and vaccine development—is generally derived from viral strains grown under laboratory conditions in immortalized cells. This study uses whole-genome sequencing of clinical strains of human parainfluenza virus 3—a globally important respiratory paramyxovirus—in cell systems that mimic the natural human host and in animal models. By examining the differences between clinical isolates and laboratory-adapted strains, the sequence differences are correlated to mechanistic differences in viral entry. For this ubiquitous and pathogenic respiratory virus to infect the human lung, modulation of the processes of receptor engagement and fusion activation occur in a manner quite different from that carried out by the entry glycoprotein-expressing pair of laboratory strains. These marked contrasts in the viral properties necessary for infection in cultured immortalized cells and in natural host tissues and animals will influence future basic and clinical studies.