Epidemiology of Human Parainfluenza Virus Type 3 and Respiratory Syncytial Virus Infections in the Time of Coronavirus Disease 2019: Findings From a Household Cohort in Maryland.

BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, human parainfluenza type 3 (HPIV-3) and respiratory syncytial virus (RSV) circulation increased as nonpharmaceutical interventions were relaxed. Using data from 175 households (n = 690 members) followed between November 2020 and October 2021, we characterized HPIV-3 and RSV epidemiology in children aged 0-4 years and their households. METHODS: Households with ≥1 child aged 0-4 years were enrolled; members collected weekly nasal swabs (NS) and additional NS with respiratory illnesses (RI). We tested NS from RI episodes in children aged 0-4 years for HPIV-3, RSV, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using reverse-transcriptase polymerase chain reaction (RT-PCR). Among children with HPIV-3 or RSV infection, we tested contemporaneous NS from household members. We compared incidence rates (IRs) of RI with each virus during epidemic periods and identified household primary cases (the earliest detected household infection), and associated community exposures. RESULTS: 41 of 175 (23.4%) households had individuals with HPIV-3 (n = 45) or RSV (n = 46) infections. Among children aged 0-4 years, RI IRs /1000 person-weeks were 8.7 [6.0, 12.2] for HPIV-3, 7.6 [4.8, 11.4] for RSV, and 1.9 [1.0, 3.5] for SARS-CoV-2. Children aged 0-4 years accounted for 35 of 36 primary HPIV-3 or RSV cases. Children attending childcare or preschool had higher odds of primary infection (odds ratio, 10.81; 95% confidence interval, 3.14-37.23). CONCLUSIONS: Among children aged 0-4 years, RI IRs for HPIV-3 and RSV infection were 4-fold higher than for SARS-CoV-2 during epidemic periods. HPIV-3 and RSV were almost exclusively introduced into households by young children.

In silico Prediction and Evaluation of Human Parainfluenza Virus-3 CD4+ T Cell Epitopes.

BACKGROUND: Human parainfluenza viruses type 3 (HPIV-3) through bronchiolitis and pneumonia is a common cause of lower respiratory tract infections. It is the main cause of hospitalization of infants and young children and also one of the main causes of morbidity and mortality in immuno-compromised and transplant patients. Despite many efforts, there is currently no specific anti-HPIV-3 drug or approved vaccine to prevent and control the virus. Identification of HPIV-3 epitopes with the capability of binding to human leukocyte antigen (HLA) class II molecules can be helpful in designing new vaccine candidates against HPIV-3 infection, and also can be useful for the in vitro stimulation and proliferation of HPIV-3-specific T cells for transplant and immunocompromised patients. OBJECTIVE: To predict and comprehensively evaluate CD4+T cell epitope (HLA-II binders) from four main HPIV-3 antigens. METHODS: In the present work, we predicted and comprehensively evaluated CD4+T cell epitope (HLA-II binders) from four main HPIV-3 antigens, including fusion protein (F), hemagglutininneuraminidase (HN), nucleocapsid (N) and matrix (M) proteins using bio- and immunoinformatics software. The toxicity, allergenicity, Blast screening and population coverage of the predicted epitopes were evaluated. The binding ability of the final selected epitopes was evaluated via a docking study. RESULTS: After several filtering steps, including blast screening, toxicity and allergenicity assay, population coverage and docking study, 9 epitopes were selected as candidate epitopes. The selected epitopes showed high population coverage and docking studies revealed a significantly higher binding affinity for the final epitopes in comparison with the negative control peptides. CONCLUSION: The final selected epitopes could be useful in designing vaccine candidates and for the treatment of immune-compromised individuals and patients with transplantation.

Solid-Phase Binding Assay for Ganglioside Binding of Human Respiroviruses.

Human parainfluenza virus types 1 (hPIV-1) and 3 (hPIV-3) belong to the family Paramyxoviridae, subfamily Paramyxoviridae, and genus Respirovirus. The viruses enter by utilizing glycoproteins or glycosphingolipids (gangliosides) containing sialic acid on the cell membrane. We developed a solid-phase binding assay to evaluate hPIV-1, hPIV-3, and Sendai virus' abilities to bind to different types of gangliosides. hPIV1 and hPIV3 show strong binding to neolacto-series gangliosides containing a non-reducing terminal sialic acid residue and different specificity regarding the sialic acid linkages. This solid-phase binding assay is suitable to evaluate other orthomyxoviruses and paramyxoviruses' binding specificities utilizing sialic acids.

Epidemiological Characteristics of Parainfluenza Virus Type 3 and the Effects of Meteorological Factors in Hospitalized Children With Lower Respiratory Tract Infection.

Objective: To investigate the relationship between meteorological factors and Human parainfluenza virus type 3 (HPIV-3) infection among hospitalized children. Methods: All hospitalized children with acute lower respiratory tract infections were tested for viral pathogens and enrolled, at the second affiliated hospital of Wenzhou medical university, between 2008 and 2017. Meteorological data were directly obtained from Wenzhou Meteorology Bureau's nine weather stations and expressed as the mean exposure for each 10-day segment (average daily temperatures, average daily relative humidity, rainfall, rainfall days, and wind speed). The correlation between meteorological factors and the incidence of HPIV-3 was analyzed, with an autoregressive integrated moving average model (ARIMA), generalized additive model (GAM), and least absolute shrinkage and selection operator (LASSO). Results: A total of 89,898 respiratory specimens were tested with rapid antigen tests, and HPIV-3 was detected in 3,619 children. HPIV-3 was detected year-round, but peak activities occurred most frequently from March to August. The GAM and LASSO-based model had revealed that HPIV-3 activity correlated positively with temperature and rainfall day, but negatively with wind speed. The ARIMA (1,0,0)(0,1,1) model well-matched the observed data, with a steady R2 reaching 0.708 (Ljung-Box Q = 21.178, P = 0.172). Conclusion: Our study suggests that temperature, rainfall days, and wind speed have significant impacts on the activity of HPIV-3. GAM, ARIMA, and LASSO-based models can well predict the seasonality of HPIV-3 infection among hospitalized children. Further understanding of its mechanism would help facilitate the monitoring and early warning of HPIV-3 infection.

Structural Basis of Human Parainfluenza Virus 3 Unassembled Nucleoprotein in Complex with Its Viral Chaperone.

Human parainfluenza virus 3 (HPIV3) belongs to the Paramyxoviridae, causing annual worldwide epidemics of respiratory diseases, especially in newborns and infants. The core components consist of just three viral proteins: nucleoprotein (N), phosphoprotein (P), and RNA polymerase (L), playing essential roles in replication and transcription of HPIV3 as well as other paramyxoviruses. Viral genome encapsidated by N is as a template and recognized by RNA-dependent RNA polymerase complex composed of L and P. The offspring RNA also needs to assemble with N to form nucleocapsids. The N is one of the most abundant viral proteins in infected cells and chaperoned in the RNA-free form (N0) by P before encapsidation. In this study, we presented the structure of unassembled HPIV3 N0 in complex with the N-terminal portion of the P, revealing the molecular details of the N0 and the conserved N0-P interaction. Combined with biological experiments, we showed that the P binds to the C-terminal domain of N0 mainly by hydrophobic interaction and maintains the unassembled conformation of N by interfering with the formation of N-RNA oligomers, which might be a target for drug development. Based on the complex structure, we developed a method to obtain the monomeric N0. Furthermore, we designed a P-derived fusion peptide with 10-fold higher affinity, which hijacked the N and interfered with the binding of the N to RNA significantly. Finally, we proposed a model of conformational transition of N from the unassembled state to the assembled state, which helped to further understand viral replication. IMPORTANCE Human parainfluenza virus 3 (HPIV3) causes annual epidemics of respiratory diseases, especially in newborns and infants. For the replication of HPIV3 and other paramyxoviruses, only three viral proteins are required: phosphoprotein (P), RNA polymerase (L), and nucleoprotein (N). Here, we report the crystal structure of the complex of N and its chaperone P. We describe in detail how P acts as a chaperone to maintain the unassembled conformation of N. Our analysis indicated that the interaction between P and N is conserved and mediated by hydrophobicity, which can be used as a target for drug development. We obtained a high-affinity P-derived peptide inhibitor, specifically targeted N, and greatly interfered with the binding of the N to RNA, thereby inhibiting viral encapsidation and replication. In summary, our results provide new insights into the paramyxovirus genome replication and nucleocapsid assembly and lay the basis for drug development.

Human Parainfluenza Virus 3 Phosphoprotein Is a Tetramer and Shares Structural and Interaction Features with Ebola Phosphoprotein VP35.

The human parainfluenza virus 3 (HPIV3) poses a risk for pneumonia development in young children and immunocompromised patients. To investigate mechanisms of HPIV3 pathogenesis, we characterized the association state and host protein interactions of HPIV3 phosphoprotein (HPIV3 P), an indispensable viral polymerase cofactor. Sequence analysis and homology modeling predict that HPIV3 P possesses a long, disordered N-terminal tail (PTAIL) a coiled-coil multimerization domain (PMD), similar to the well-characterized paramyxovirus phosphoproteins from measles and Sendai viruses. Using a recombinantly expressed and purified construct of PMD and PTAIL, we show that HPIV3 P in solution is primarily an alpha-helical tetramer that is stable up to 60 °C. Pulldown and isothermal titration calorimetry experiments revealed that HPIV3 P binds the host hub protein LC8, and turbidity experiments demonstrated a new role for LC8 in increasing the solubility of HPIV3 P in the presence of crowding agents such as RNA. For comparison, we show that the multimerization domain of the Zaire Ebola virus phosphoprotein VP35 is also a tetramer and binds LC8 but with significantly higher affinity. Comparative analysis of the domain architecture of various virus phosphoproteins in the order Mononegavirales show multiple predicted and verified LC8 binding motifs, suggesting its prevalence and importance in regulating viral phosphoprotein structures. Our work provides evidence for LC8 binding to phosphoproteins with multiple association states, either tetrameric, as in the HPIV3 and Ebola phosphoproteins shown here, or dimeric as in rabies virus phosphoprotein. Taken together the data suggest that the association states of a virus-specific phosphoprotein and the complex formed by binding of the phosphoprotein to host LC8 are important regulators of viral function.

Human parainfluenza virus type 3 infections in a haemato-oncology unit: social distancing measures needed in outpatient clinics.

BACKGROUND: Human parainfluenza virus type 3 (HPIV3) infections are associated with high mortality in immunocompromised settings, especially in bone marrow transplant recipients. Asymptomatic infection and lack of effective antiviral treatment makes HPIV3 prevention and treatment a real challenge. AIM: To retrospectively investigate the epidemiological characteristics, clinical characteristics and outcomes of 51 haematology patients with confirmed HPIV3 infections, detected between February and May 2019 in the haematology unit at King's College Hospital, London. METHODS: Between February and May 2019, HPIV3 RNA was detected in combined nose and throat swab samples collected from 51 symptomatic haematology patients, 41 of whom attended the haematology outpatient unit. Clinical data were reviewed retrospectively and a timeline of patients' appointments drawn up to investigate transmission. Sequencing analysis was performed on 14 stored samples. FINDINGS: Fifty-one patients were identified with HPIV3 infection. Mean age was 54 years (SD: 12; range: 19-72) and 60% (31/51) were male. There were 41 (80%) bone marrow transplant recipients, 24 had an allograft, and 17 an autograft. Thirty-day and 3-month mortality post HPIV3 was 6% and 14%, respectively. Lower respiratory tract infection and inpatient acquisition were associated with higher mortality (6/7 vs 1/7, P = 0.010; and 5/7 vs 2/7, P = 0.031). Onset of HPIV3 infection in patients within 6 days of attending the clinic was associated with the clusters identified in phylogenetic analysis (64% (9/14) vs 21% (8/37); odds ratio: 6.5 (confidence interval: 95% 1.7-25); P = 0.006). CONCLUSION: Timelines suggested community transmission, but also possible transmission patterns within the outpatients and subsequent nosocomial transmission within the same ward. Early recognition of HPIV3 infection and the use of polymerase chain reaction and sequence analysis is fundamental in identifying respiratory virus outbreaks and person-to-person transmission. Careful planning of outpatient clinic attendance is required to minimize contact and prevent respiratory virus transmission in immunosuppressed patients.

Sumoylation of Human Parainfluenza Virus Type 3 Phosphoprotein Correlates with A Reduction in Viral Replication.

Human parainfluenza virus type 3 (HPIV3), a member of the Paramyxoviridae family, can cause lower respiratory disease in infants and young children. The phosphoprotein (P) of HPIV3 is an essential cofactor of the viral RNA-dependent RNA polymerase large protein (L). P connects nucleocapsid protein (N) with L to initiate genome transcription and replication. Sumoylation influences many important pathways of the target proteins, and many viral proteins are also themselves sumoylated. In this study, we found that the P of HPIV3 could be sumoylated, and mutation of K492 and K532 to arginine (PK492R/K532R) failed to be sumoylated within P, which enhances HPIV3 minigenome activity. Biochemical studies showed that PK492R/K532R had no effect on its interactions with N, formation of homo-tetramers and formation of inclusion bodies. Finally, we found that incorporation of K492R/K532R into a recombinant HPIV3 (rHPIV3-PK492R/K532R) increased viral production in culture cells, suggesting that sumoylation attenuates functions of P and down-regulates viral replication.

Effects of Single α-to-ß Residue Replacements on Recognition of an Extended Segment in a Viral Fusion Protein.

Partial replacement of α-amino acid residues with ß-amino acid residues has been established as a strategy for preserving target-engagement by helix-forming polypeptides while altering other properties. The impact of ß-residue incorporation within polypeptides that adopt less regular conformations, however, has received less attention. The C-terminal heptad repeat (HRC) domains of fusion glycoproteins from pathogenic paramyxoviruses contain a segment that must adopt an extended conformation in order to coassemble with the N-terminal heptad repeat (HRN) domain in the postfusion state and drive a merger of the viral envelope with a target cell membrane. Here, we examine the impact of single α-to-ß substitutions within this extended N-terminal segment of an engineered HRC peptide designated VIQKI. Stabilities of hexameric coassemblies formed with the native human parainfluenza virus 3 (HPIV3) HRN have been evaluated, the structures of five coassemblies have been determined, and antiviral efficacies have been measured. Many sites within the extended segment show functional tolerance of α-to-ß substitution. These results offer a basis for future development of paramyxovirus infection inhibitors with novel biological activity profiles, possibly including resistance to proteolysis.

PI4KB on Inclusion Bodies Formed by ER Membrane Remodeling Facilitates Replication of Human Parainfluenza Virus Type 3.

Many positive-strand RNA viruses remodel the endomembrane to form specialized replication organelles. However, knowledge regarding whether negative-strand RNA viruses take advantage of intracellular membranes for replication is limited. Here we show that a negative-strand RNA virus, human parainfluenza virus type 3 (HPIV3), remodels the endoplasmic reticulum (ER) membrane to form inclusion bodies (IBs), whereby the phosphoprotein (P) of HPIV3 recruits phosphatidylinositol 4-kinase beta (PI4KB) to IBs to generate PI4P, creating a PI4P-enriched microenvironment to promote HPIV3 replication. In addition, we find that human respiratory syncytial virus (HRSV) also takes advantage of the ER to form IBs and that these IBs are also enriched with PI4P. The nucleoprotein of HRSV recruits PI4KB to IBs. These results suggest that paramyxoviruses also exploit the host endomembrane to form IBs and that PI4KB is recruited by viral proteins to enrich IBs with PI4P to facilitate viral replication.

Virion-Associated Cholesterol Regulates the Infection of Human Parainfluenza Virus Type 3.

The matrix (M) proteins of paramyxoviruses bind to the nucleocapsids and cytoplasmic tails of glycoproteins, thus mediating the assembly and budding of virions. We first determined the budding characterization of the HPIV3 Fusion (F) protein to investigate the assembly mechanism of human parainfluenza virus type 3 (HPIV3). Our results show that expression of the HPIV3 F protein alone is sufficient to initiate the release of virus-like particles (VLPs), and the F protein can regulate the VLP-forming ability of the M protein. Furthermore, HPIV3F-Flag, which is a recombinant HPIV3 with a Flag tag at the C-terminus of the F protein, was constructed and recovered. We found that the M, F, and hemagglutinin-neuraminidase (HN) proteins and the viral genome can accumulate in lipid rafts in HPIV3F-Flag-infected cells, and the F protein mainly exists in the form of F1 in VLPs, lipid rafts, and purified virions. Furthermore, the function of cholesterol in the viral envelope and cell membrane was assessed via the elimination of cholesterol by methyl-ß-cyclodextrin (MßCD). Our results suggest that the infectivity of HPIV3 was markedly reduced, due to defective internalization ability in the absence of cholesterol. These results reveal that HPIV3 might assemble in the lipid rafts to acquire cholesterol for the envelope of HPIV3, which suggests the that disruption of the cholesterol composition of HPIV3 virions might be a useful method for the design of anti-HPIV3 therapy.

Haemagglutinin-neuraminidase from HPIV3 mediates human NK regulation of T cell proliferation via NKp44 and NKp46.

HPIV3 is a respiratory virus causing airway diseases, including pneumonia, croup, and bronchiolitis, during infancy and childhood. Currently there is no effective vaccine or anti-viral therapy for this virus. Studies have suggested that poor T cell proliferation following HPIV3 infection is responsible for impaired immunological memory associated with this virus. We have previously demonstrated that NK cells mediate regulation of T cell proliferation during HPIV3 infection. Here we add to these studies by demonstrating that the regulation of T cell proliferation during HPIV3 infection is mediated via NK receptors NKp44 and NKp46 and involves the surface glycoprotein haemagglutinin-neuraminidase but not the fusion protein of the virus. These studies extend our knowledge of the regulatory repertoire of NK cells and provide mechanistic insights which may explain reoccurring failures of vaccines against this virus.

Characterization of the nasopharyngeal viral microbiome from children with community-acquired pneumonia but negative for Luminex xTAG respiratory viral panel assay detection.

In the present study, 50 nasopharyngeal swabs from children with community-acquired pneumonia (CAP) but negative for 18 common respiratory viruses, as measured by the Luminex xTAG Respiratory Viral Panel Assay, were subjected to multiplex metagenomic analyses using a next-generation sequencing platform. Taxonomic analysis showed that all sequence reads could be assigned to a specific species. An average of 95.13% were assigned to the Bacteria kingdom, whereas, only 0.72% were potentially virus derived. This snapshot of the respiratory tract virome revealed most viral reads to be respiratory tract related, classified into four known virus families: Paramyxoviridae, Herpesviridae, Anelloviridae, and Polyomaviridae. Importantly, we detected a novel human parainfluenza virus 3 (HPIV 3) strain with a 32-bp insertion in the haemagglutinin-neuraminidase (HN) gene that produced a negative result in the Luminex assay, highlighting the strength of virome metagenomic analysis to identify not only novel viruses but also viruses likely to be missed by ordinary clinical tests. Thus, virome metagenomic analysis could become a viable clinical diagnostic method.

The role of next generation sequencing in infection prevention in human parainfluenza virus 3 infections in immunocompromised patients.

BACKGROUND: Respiratory viral infections are a significant problem in patients with hematologic malignancies. We report a cluster of HPIV 3 infections in our myeloma patients, and describe the utility of next generation sequencing (NGS) to identify transmission linkages which can assist in infection prevention. OBJECTIVES: To evaluate the utility of NGS to track respiratory viral infection outbreaks and delineate between community acquired and nosocomial infections in our cancer units. STUDY DESIGN: Retrospective chart review conducted at a single site. All patients diagnosed with multiple myeloma who developed symptoms suggestive of upper respiratory tract infection (URTI) or lower respiratory tract infection (LRTI) along with a respiratory viral panel (RVP) test positive for HPIV 3 between April 1, 2016, to June 30, 2016, were included. Sequencing was performed on the Illumina MiSeq™. To gain understanding regarding community strains of HPIV 3 during the same season, we also performed NGS on HPIV3 strains isolated from pediatric cases. RESULTS: We saw a cluster of 13 cases of HPIV3 infections in the myeloma unit. Using standard epidemiologic criteria, 3 cases were considered community acquired, 7 cases developed infection during treatment in the cancer infusion center, while an additional 3 developed infections during hospital stay. Seven patients required hospitalization for a median duration of 20days. NGS enabled sensitive discrimination of the relatedness of the isolates obtained during the outbreak and provided evidence for source of transmission. Two hospital onset infections could be tracked to an index case; the genome sequences of HPIV 3 strains from these 3 patients only differed by a single nucleotide. CONCLUSIONS: NGS offers a significantly higher discriminatory value as an epidemiologic tool, and can be used to gather real-time information and identification of transmission linkages to assist in infection prevention in immunocompromised patients.

Rule-Out Outbreak: 24-Hour Metagenomic Next-Generation Sequencing for Characterizing Respiratory Virus Source for Infection Prevention.

BACKGROUND.: Metagenomic next-generation sequencing (mNGS) has been used to uncover unusual causes of infectious diseases but has not been used routinely for the investigation of putative nosocomial outbreaks. Here, we describe the use of mNGS during investigation of a cluster of human rhinovirus (HRV)-positive infections on a high-risk pulmonary ward. METHODS.: We performed mNGS on 6 midnasal turbinate swabs from 4 case-patients and 10 swabs from 9 control outpatients that tested positive for enterovirus/rhinovirus by the FilmArray system. RESULTS.: HRV reads were recovered in 15 (94%) of the 16 samples sequenced. Phylogenetic analysis of HRV whole genomes from the 4 case-patients and 5 outpatient controls along with partial genomes from additional outpatient controls revealed that isolates from the case-patients were not directly related and that the 2 closest case HRV genomes had an estimated time to most recent common ancestor of 172 years. Our turnaround time from receipt of the sample to phylogenetic analysis was 24 hours. CONCLUSIONS.: We found the use of mNGS downstream of a rapid polymerase chain reaction respiratory panel during an investigation of 4 hospital-acquired rhinovirus infections to rapidly dispel concern of a single-source transmission event.

The Matrix Protein of Human Parainfluenza Virus Type 3 Induces Mitophagy that Suppresses Interferon Responses.

Mitophagy is a form of autophagy that selectively removes damaged mitochondria. Impaired mitochondria can be tagged by the kinase PINK1, which triggers recruitment of the E3-ubiquitin ligase Parkin and subsequent mitochondrial sequestration within autophagosomes. We previously found that human parainfluenza virus type 3 (HPIV3) infection induces autophagy, but the type and mechanisms of autophagy induction remain unknown. Here, we show that matrix protein (M) of HPIV3 translocates to mitochondria and interacts with Tu translation elongation factor mitochondrial (TUFM). M-mediated mitophagy does not require the Parkin-PINK1 pathway but rather an interaction between M and the LC3 protein that mediates autophagosome formation. These interactions with both TUFM and LC3 are required for the induction of mitophagy and lead to inhibition of the type I interferon response. These results reveal that a viral protein is sufficient to induce mitophagy by bridging autophagosomes and mitochondria.

Legionnaire's Disease and its Mimics: A Clinical Perspective.

Whenever the cardinal manifestations of a disorder occur in similar disorders, there is potential for a disease mimic. Legionnaire's disease has protean manifestations and has the potential to mimic or be mimicked by other community acquired pneumonias (CAPs). In CAPs caused by other than Legionella species, the more characteristic features in common with legionnaire's disease the more difficult the diagnostic conundrum. In hospitalized adults with CAP, legionnaire's disease may mimic influenza or other viral pneumonias. Of the bacterial causes of CAP, psittacosis and Q fever, but not tularemia, are frequent mimics of legionnaire's disease.

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.

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.