Quantifying dose-, strain-, and tissue-specific kinetics of parainfluenza virus infection.

Human parainfluenza viruses (HPIVs) are a leading cause of acute respiratory infection hospitalization in children, yet little is known about how dose, strain, tissue tropism, and individual heterogeneity affects the processes driving growth and clearance kinetics. Longitudinal measurements are possible by using reporter Sendai viruses, the murine counterpart of HPIV 1, that express luciferase, where the insertion location yields a wild-type (rSeV-luc(M-F*)) or attenuated (rSeV-luc(P-M)) phenotype. Bioluminescence from individual animals suggests that there is a rapid increase in expression followed by a peak, biphasic clearance, and resolution. However, these kinetics vary between individuals and with dose, strain, and whether the infection was initiated in the upper and/or lower respiratory tract. To quantify the differences, we translated the bioluminescence measurements from the nasopharynx, trachea, and lung into viral loads and used a mathematical model together a nonlinear mixed effects approach to define the mechanisms distinguishing each scenario. The results confirmed a higher rate of virus production with the rSeV-luc(M-F*) virus compared to its attenuated counterpart, and suggested that low doses result in disproportionately fewer infected cells. The analyses indicated faster infectivity and infected cell clearance rates in the lung and that higher viral doses, and concomitantly higher infected cell numbers, resulted in more rapid clearance. This parameter was also highly variable amongst individuals, which was particularly evident during infection in the lung. These critical differences provide important insight into distinct HPIV dynamics, and show how bioluminescence data can be combined with quantitative analyses to dissect host-, virus-, and dose-dependent effects.

Clinical features of parainfluenza infections among young children hospitalized for acute respiratory illness in Amman, Jordan.

BACKGROUND: Parainfluenza virus (PIV) is a leading cause of acute respiratory illness (ARI) in children. However, few studies have characterized the clinical features and outcomes associated with PIV infections among young children in the Middle East. METHODS: We conducted hospital-based surveillance for ARI among children < 2 years of age in a large referral hospital in Amman, Jordan. We systematically collected clinical data and respiratory specimens for pathogen detection using reverse transcription polymerase chain reaction. We compared clinical features of PIV-associated ARI among individual serotypes 1, 2, 3, and 4 and among PIV infections compared with other viral ARI and ARI with no virus detected. We also compared the odds of supplemental oxygen use using logistic regression. RESULTS: PIV was detected in 221/3168 (7.0%) children hospitalized with ARI. PIV-3 was the most commonly detected serotype (125/221; 57%). Individual clinical features of PIV infections varied little by individual serotype, although admission diagnosis of 'croup' was only associated with PIV-1 and PIV-2. Children with PIV-associated ARI had lower frequency of cough (71% vs 83%; p < 0.001) and wheezing (53% vs 60% p < 0.001) than children with ARI associated with other viruses. We did not find a significant difference in supplemental oxygen use between children with PIV-associated infections (adjusted odds ratio [aOR] 1.12, 95% CI 0.66-1.89, p = 0.68) and infections in which no virus was detected. CONCLUSIONS: PIV is frequently associated with ARI requiring hospitalization in young Jordanian children. Substantial overlap in clinical features may preclude distinguishing PIV infections from other viral infections at presentation.

Respiratory Virus Infections in Asthma: Research Developments and Therapeutic Advances.

In this review, we discuss the latest developments in research pertaining to virus-induced asthma exacerbations and consider recent advances in treatment options. Asthma is a chronic disease of the airways that continues to impose a substantial clinical burden worldwide. Asthma exacerbations, characterised by an acute deterioration in respiratory symptoms and airflow obstruction, are associated with significant morbidity and mortality. These episodes are most commonly triggered by respiratory virus infections. The mechanisms underlying the pathogenesis of virus-induced exacerbations have been the focus of extensive biomedical research. Developing a robust understanding of the interplay between respiratory viruses and the host immune response will be critical for developing more efficacious, targeted therapies for exacerbations. CONCLUSION: There has been significant recent progress in our understanding of the mechanisms underlying virus-induced airway inflammation in asthma and these advances will underpin the development of future clinical therapies.

Time-course of upper respiratory tract viral infection and COPD exacerbation.

Viral respiratory tract infections have been implicated as the predominant risk factor for acute exacerbations of chronic obstructive pulmonary disease (AECOPD). We aimed to evaluate, longitudinally, the association between upper respiratory tract infections (URTI) caused by viruses and AECOPD.Detection of 18 viruses was performed in naso- and orοpharyngeal swabs from 450 COPD patients (Global Initiative for Chronic Obstructive Lung Disease stages 2-4) who were followed for a mean of 27 months. Swabs were taken during stable periods (n=1909), at URTI onset (n=391), 10 days after the URTI (n=356) and during an AECOPD (n=177) and tested using a multiplex nucleic acid amplification test.Evidence of at least one respiratory virus was significantly higher at URTI onset (52.7%), 10 days after the URTI (15.2%) and during an AECOPD (38.4%), compared with the stable period (5.3%, p<0.001). During stable visits, rhinovirus accounted for 54.2% of all viral infections, followed by coronavirus (20.5%). None of the viruses were identified in two consecutive stable visits. Patients with a viral infection at URTI onset did not have a higher incidence of exacerbation than patients without viral infection (p=0.993). Τhe incidence of any viral infection during an AECOPD was similar between URTI-related AECOPD and non-URTI-related AECOPD (p=0.359). Only 24% of the patients that had a URTI-related AECOPD had the same virus at URTI onset and during an AECOPD. Detection of parainfluenza 3 at URTI onset was associated with a higher risk of an AECOPD (p=0.003). Rhinovirus and coronavirus were the most frequently detected viruses during AECOPD visits, accounting for 35.7% and 25.9% of all viral infections, respectively.The prevalence of viral infection during the stable period of COPD was low. The risk of exacerbation following the onset of URTI symptoms depends on the particular virus associated with the event and was significant only for parainfluenza 3.

Human metapneumovirus infection of airway epithelial cells is associated with changes in core metabolic pathways.

Human metapneumovirus (hMPV) is an important cause of acute lower respiratory tract infections in infants, elderly and immunocompromised individuals. Ingenuity pathway analysis of microarrays data showed that 20% of genes affected by hMPV infection of airway epithelial cells (AECs) were related to metabolism. We found that levels of the glycolytic pathway enzymes hexokinase 2, pyruvate kinase M2, and lactate dehydrogenase A were significantly upregulated in normal human AECs upon hMPV infection, as well as levels of enzymes belonging to the hexosamine biosynthetic and glycosylation pathways. On the other hand, expression of the majority of the enzymes belonging to the tricarboxylic acid cycle was significantly diminished. Inhibition of hexokinase 2 and of the glycosylating enzyme O-linked N-acetylglucosamine transferase led to a significant reduction in hMPV titer, indicating that metabolic changes induced by hMPV infection play a major role during the virus life cycle, and could be explored as potential antiviral targets.

The role of human Metapneumovirus genetic diversity and nasopharyngeal viral load on symptom severity in adults.

BACKGROUND: Human metapneumovirus (HMPV) is established as one of the causative agents of respiratory tract infections. To date, there are limited reports that describe the effect of HMPV genotypes and/or viral load on disease pathogenesis in adults. This study aims to determine the role of HMPV genetic diversity and nasopharyngeal viral load on symptom severity in outpatient adults with acute respiratory tract infections. METHODS: Severity of common cold symptoms of patients from a teaching hospital was assessed by a four-category scale and summed to obtain the total symptom severity score (TSSS). Association between the fusion and glycoprotein genes diversity, viral load (quantified using an improved RT-qPCR assay), and symptom severity were analyzed using bivariate and linear regression analyses. RESULTS: Among 81/3706 HMPV-positive patients, there were no significant differences in terms of demographics, number of days elapsed between symptom onset and clinic visit, respiratory symptoms manifestation and severity between different HMPV genotypes/sub-lineages. Surprisingly, elderly patients (≥65 years old) had lower severity of symptoms (indicated by TSSS) than young and middle age adults (p = 0.008). Nasopharyngeal viral load did not correlate with nor predict symptom severity of HMPV infection. Interestingly, at 3-5 days after symptom onset, genotype A-infected patients had higher viral load compared to genotype B (4.4 vs. 3.3 log10 RNA copies/µl) (p = 0.003). CONCLUSIONS: Overall, HMPV genetic diversity and viral load did not impact symptom severity in adults with acute respiratory tract infections. Differences in viral load dynamics over time between genotypes may have important implications on viral transmission.

Human Metapneumovirus Infections Following Hematopoietic Cell Transplantation: Factors Associated With Disease Progression.

BACKGROUND: Human metapneumovirus (HMPV) is a newly identified pulmonary pathogen that can cause fatal lower respiratory tract disease (LRD) in hematopoietic cell transplantation (HCT) recipients. Little is known about progression rates from upper respiratory tract infection (URI) to LRD and risk factors associated with progression. METHODS: A total of 118 HCT recipients receiving transplantation between 2004 and 2014 who had HMPV detected in nasopharyngeal, bronchoalveolar lavage, or lung biopsy samples by real-time reverse transcription polymerase chain reaction were retrospectively analyzed. RESULTS: More than 90% of the cases were identified between December and May. Among the 118 HCT patients, 88 and 30 had URI alone and LRD, respectively. Among 30 patients with LRD, 17 patients progressed from URI to LRD after a median of 7 days (range, 2-63 days). The probability of progression to LRD within 40 days after URI was 16%. In Cox regression analysis, steroid use ≥1 mg/kg prior to URI diagnosis (hazard ratio [HR], 5.10; P = .004), low lymphocyte count (HR, 3.43; P = .011), and early onset of HMPV infection after HCT (before day 30 after HCT; HR, 3.54; P = .013) were associated with higher progression to LRD. The median viral load in nasal wash samples was 1.1 × 10(6) copies/mL (range, 3.3 × 10(2)-1.7 × 10(9)) with no correlation between the viral load and progression. CONCLUSIONS: Progression from URI to LRD occurred in up to 60% of HCT recipients with risk factors such as systemic corticosteroid use or low lymphocyte counts. Further studies are needed to define the role of viral load in the pathogenesis of progressive disease.

Integrin αvß1 Modulation Affects Subtype B Avian Metapneumovirus Fusion Protein-mediated Cell-Cell Fusion and Virus Infection.

Avian metapneumovirus (aMPV) fusion (F) protein mediates virus-cell membrane fusion to initiate viral infection, which requires F protein binding to its receptor(s) on the host cell surface. However, the receptor(s) for aMPV F protein is still not identified. All known subtype B aMPV (aMPV/B) F proteins contain a conserved Arg-Asp-Asp (RDD) motif, suggesting that the aMPV/B F protein may mediate membrane fusion via the binding of RDD to integrin. When blocked with integrin-specific peptides, aMPV/B F protein fusogenicity and viral replication were significantly reduced. Specifically we identified integrin αv and/or ß1-mediated F protein fusogenicity and viral replication using antibody blocking, small interfering RNAs (siRNAs) knockdown, and overexpression. Additionally, overexpression of integrin αv and ß1 in aMPV/B non-permissive cells conferred aMPV/B F protein binding and aMPV/B infection. When RDD was altered to RAE (Arg-Ala-Glu), aMPV/B F protein binding and fusogenic activity were profoundly impaired. These results suggest that integrin αvß1 is a functional receptor for aMPV/B F protein-mediated membrane fusion and virus infection, which will provide new insights on the fusogenic mechanism and pathogenesis of aMPV.

Incidence and Clinical Course of Respiratory Viral Coinfections in Children Aged 0-59 Months.

Clinical data available on coinfections are contradictory concerning both the number of viruses involved and the severity of the condition. A total of 114 patients aged 0-59 months with symptoms of respiratory tract infection were enrolled into the study. Nasal and pharyngeal swabs were tested using the PCR method for the following 12 viruses: influenza A, influenza B, respiratory syncytial virus A (RSV A), respiratory syncytial virus B (RSV B), adenovirus, metapneumovirus, coronavirus 229E/NL63 (hCoV229), coronavirus OC43 (hCoVOC43), parainfluenza virus 1 (PIV-1), parainfluenza virus 2 (PIV-2), parainfluenza virus 3 (PIV-3), and rhinovirus A/B. Coinfections were detected in nine (8 %) patients. Five of the coinfections were related to influenza A (H3N2) virus associated with the following other, single or combined, respiratory viruses: influenza B in one case, hCoV229 in two cases, hCoV229, RSV A, and PIV-2 in one case, and PIV-1, PIV-2, RSV A, RSV B, and adenovirus in one case. The other four coinfections were caused by: adenovirus and hCoVOC43, adenovirus, and rhinovirus, RSV A and PIV-1, influenza B, and RSV B. We did not observe any significant differences in the clinical course of infections caused either by a single or multiple viral factors.

Virus distribution and detection in corn snakes (Pantherophis guttatus) after experimental infection with three different ferlavirus strains.

Ferlaviruses are important pathogens of snakes. However, factors influencing the pathogenicity of individual isolates as well as optimal protocols for virus detection in tissues of infected snakes have been insufficiently studied. The objectives of this study were to compare virus detection using previously described PCR and cell culture protocols following infection with three genetically distinct ferlaviruses in corn snakes (Pantherophis guttatus) as a model species. Groups of 12 corn snakes were each inoculated intratracheally with a genogroup A, B, or C ferlavirus. Tracheal washes and cloacal swabs were tested for virus shedding on days 16 and 28. Three animals were each euthanized on days 4, 16, 28, and 49. Beside immunohistochemistry of lung tissue, several organs (lung, intestine, pancreas, kidney, brain) were tested for the presence of ferlavirus. Distinct differences were noted in the pathogenicity of the three viruses, with a genotype B isolate causing the greatest pathology. PCR was more sensitive in comparison to cell culture, but results varied depending on the tissues. Ferlaviruses spread rapidly into the tissues, including the brain. Overall average detection rate was 72%, and was highest on day 16. There were differences between the groups, with the most virulent strain causing 100% positive samples at the end of the study. Some snakes were able to clear the infection. Shedding via cloaca was seen only on day 28. For ante-mortem sampling, a tracheal wash sample is recommended, for post mortem diagnosis, a pooled organ sample should be tested.

Isolation & molecular characterization of human parainfluenza virus in Chennai, India.

BACKGROUND & OBJECTIVES: Human parainfluenza virus (HPIV) accounts for a significant proportion of lower respiratory tract infections in children as well as adults. This study was done to detect the presence of different subtypes of HPIV from patients having influenza like illness (ILI). METHODS: Throat and nasal swabs from 232 patients with ILI who were negative for influenza viruses were tested by multiplex reverse transcription polymerase chain reaction(mRT-PCR) for the detection of human parainfluenza virus. All samples were inoculated in rhesus monkey kidney (LLC-MK2) cell line. RESULTS: Of the 232 samples, 26(11.2%) were positive by mRT-PCR and nine (34.6%) showed cytopathic effect with syncytium formation for HPIV and all were HPIV-3 serotype, other serotypes like 1,2,4 were negative. The HPIV-3 strains (HN gene) were sequenced and analysed. Two novel mutations were identified at amino acid residues 295 and 297. INTERPRETATION & CONCLUSIONS: The mRT-PCR assay offers a rapid, sensitive and accurate diagnostic method for detection of HPIV which enables early detection and control. In our study there was a predominance of HPIV among 1-5 yr age group and the school going age group was less affected. Further studies need to be done to characterize HPIV isolated from different parts of the country.

Interleukin-1ß mediates virus-induced m2 muscarinic receptor dysfunction and airway hyperreactivity.

Respiratory viral infections are associated with the majority of asthma attacks. Inhibitory M2 receptors on parasympathetic nerves, which normally limit acetylcholine (ACh) release, are dysfunctional after respiratory viral infection. Because IL-1ß is up-regulated during respiratory viral infections, we investigated whether IL-1ß mediates M2 receptor dysfunction during parainfluenza virus infection. Virus-infected guinea pigs were pretreated with the IL-1ß antagonist anakinra. In the absence of anakinra, viral infection increased bronchoconstriction in response to vagal stimulation but not to intravenous ACh, and neuronal M2 muscarinic receptors were dysfunctional. Pretreatment with anakinra prevented virus-induced increased bronchoconstriction and M2 receptor dysfunction. Anakinra did not change smooth muscle M3 muscarinic receptor response to ACh, lung viral loads, or blood and bronchoalveolar lavage leukocyte populations. Respiratory virus infection decreased M2 receptor mRNA expression in parasympathetic ganglia extracted from infected animals, and this was prevented by blocking IL-1ß or TNF-α. Treatment of SK-N-SH neuroblastoma cells or primary cultures of guinea pig parasympathetic neurons with IL-1ß directly decreased M2 receptor mRNA, and this was not synergistic with TNF-α treatment. Treating guinea pig trachea segment with TNF-α or IL-1ß in vitro increased tracheal contractions in response to activation of airway nerves by electrical field stimulation. Blocking IL-1ß during TNF-α treatment prevented this hyperresponsiveness. These data show that virus-induced hyperreactivity and M2 dysfunction involves IL-1ß and TNF-α, likely in sequence with TNF-α causing production of IL-1ß.

Alveolar macrophages contribute to the pathogenesis of human metapneumovirus infection while protecting against respiratory syncytial virus infection.

Human metapneumovirus (hMPV) and respiratory syncytial virus (RSV) are leading causes of upper and lower respiratory tract infections in young children and among elderly and immunocompromised patients. The pathogenesis of hMPV-induced lung disease is poorly understood. The lung macrophage population consists of alveolar macrophages (AMs) residing at the luminal surface of alveoli and interstitial macrophages present within the parenchymal lung interstitium. The involvement of AMs in innate immune responses to virus infections remains elusive. In this study, BALB/c mice depleted of AMs by intranasal instillation of dichloromethylene bisphosphonate (L-CL2MBP) liposomes were examined for disease, lung inflammation, and viral replication after infection with hMPV or RSV. hMPV-infected mice lacking AMs exhibited improved disease in terms of body weight loss, lung inflammation, airway obstruction, and hyperresponsiveness compared with AM-competent mice. AM depletion was associated with significantly reduced hMPV titers in the lungs, suggesting that hMPV required AMs for early entry and replication in the lung. In contrast, AM depletion in the context of RSV infection was characterized by an increase in viral replication, worsened disease, and inflammation, with increased airway neutrophils and inflammatory dendritic cells. Overall, lack of AMs resulted in a broad-spectrum disruption in type I IFN and certain inflammatory cytokine production, including TNF and IL-6, while causing a virus-specific alteration in the profile of several immunomodulatory cytokines, chemokines, and growth factors. Our study demonstrates that AMs have distinct roles in the context of human infections caused by members of the Paramyxoviridae family.

Ten years of human metapneumovirus research.

Described for the first time in 2001, human metapneumovirus (hMPV) has become one of the main viral pathogens responsible for acute respiratory tract infections in children but also in the elderly and immuno-compromised patients. The pathogen most closely related to hMPV is human respiratory syncytial virus (hRSV), the most common cause of bronchiolitis and pneumonia in young children. hMPV has been classified into two main viral groups A and B and has a seasonal distribution in temperate countries with most cases occurring in winter and spring. Given the difficulties encountered in culturing hMPV in vitro, diagnosis is generally achieved using real-time polymerase chain reaction. Like other Paramyxoviridae, hMPV has a negative-sense single-stranded RNA genome that includes 8 genes coding for 9 different proteins. The genomic organization and functions of surface attachment and fusion glycoproteins are relatively similar to those of hRSV. Although many groups have studied the viral life cycle of hMPV, many questions remain unanswered concerning the exact roles of the viral proteins in the attachment, fusion and replication of hMPV. To date, there remains no approved modality to combat hMPV infections. The majority of treatments that have been tested on hMPV have already demonstrated activity against hRSV infections. Some innovative approaches based on RNA interference and on fusion inhibitors have shown efficacy in vitro and in animal studies and could be beneficial in treating human hMPV disease. Difficulties faced inducing a durable immune response represent the biggest challenge in the development of an effective hMPV vaccine. Several strategies, such as the use of live-attenuated viruses generated by reverse genetics or recombinant proteins, have been tested in animals with encouraging results.

An outbreak of severe respiratory tract infection due to human metapneumovirus in a long-term care facility for the elderly in Oregon.

Human metapneumovirus (hMPV) was demonstrated to be responsible for an outbreak of acute respiratory tract infection with high morbidity and mortality among residents of a long-term care facility for the elderly during the late spring-summer in Oregon. Respiratory virus infections are a common cause of death in the elderly and the burden of human metapneumovirus may be underestimated. This case report stresses the importance of hMPV in causing outbreaks in long-term care facilities for the elderly. Cough and elevated temperature were common to all the resident patient cases. Six resident patient cases had hMPV laboratory confirmation of which 5 had the diagnosis of pneumonia and 4 were hospitalized. The fatality rate was 33.3% among laboratory confirmed cases and 31.3.0% among probable resident patient cases. The signs and symptoms observed in the elderly with acute respiratory infection caused by hMPV are difficult to distinguish from those associated with other respiratory viruses and direct testing for hMPV with molecular methods should be routinely pursued to prevent nosocomial infections.

The human metapneumovirus: a case series and review of the literature.

Human metapneumovirus (hMPV) is an emerging human pulmonary pathogen that is genetically related to respiratory syncytial virus. It has been increasingly associated with respiratory illnesses over the last few decades. Immunocompromised patients are particularly susceptible with resultant morbidity and mortality. We describe our experience with 9 immunocompromised patients diagnosed with pneumonia secondary to hMPV, 2 of whom were successfully treated with aerosolized and oral ribavirin along with intravenous immunoglobulin (IVIG). We suggest that hMPV should be considered in the differential diagnosis of immunocompromised patients with acute respiratory illness. Ribavirin (oral and aerosolized) with IVIG is potentially an effective treatment option for those with severe disease.

Comparison of human metapneumovirus and respiratory syncytial virus in children admitted to a paediatric intensive care unit.

AIM: To describe the clinical presentation and course of children admitted to the paediatric intensive care unit (PICU) with human metapneumovirus (hMPV) infection, and compare them with children admitted to the PICU with respiratory syncytial virus (RSV) infection. METHODS: hMPV was identified by immunofluorescence in 22 children admitted to the PICU over a 16-month period. The medical records of these children were reviewed retrospectively, and their clinical and laboratory data were compared with 66 children admitted to the PICU with positive tests for RSV over the same period. RESULTS: Children admitted to the PICU with hMPV were significantly older than children with RSV (P= 0.003). Children with hMPV presented more commonly with pneumonia or pneumonitis (29% vs. 16%), and less commonly with bronchiolitis (43% vs. 68%) than RSV (P= 0.13). Invasive ventilation was required in 10 patients (48%) with hMPV, and non-invasive ventilation was required in a further 5 (28%), similar to patients with RSV. Children with hMPV were more likely to have an underlying co-morbidity (P= 0.11). CONCLUSIONS: Children admitted to the PICU with hMPV have a similar disease presentation and severity as children admitted with RSV, including some with extremely severe disease who require additional ventilatory or cardiovascular support. Children with hMPV are likely to be older than those with RSV, and more likely to present with pneumonia and less likely to present with bronchiolitis.

Clinical and epidemiological comparison of human metapneumovirus and respiratory syncytial virus in seoul, Korea, 2003-2008.

Human metapneumovirus (HMPV) shares clinical and epidemiological characteristics with well-known respiratory syncytial virus (RSV). The aim of this study was to investigate the clinical and epidemiological differences between HMPV- and RSV-induced wheezing illnesses. A total of 1,008 nasopharyngeal aspirate specimens was collected from 1,008 pediatric patients hospitalized with acute respiratory tract infection at Inje University Sanggye Paik Hospital from December 2003 to April 2008, and tested for seven common respiratory viruses. Conditions classified as wheezing illness were bronchiolitis, reactive airways disease, and bronchial asthma. HMPV caused a significantly lower proportion of wheezing illness when compared to RSV (48.1% vs. 82.2%, P<0.05). HMPV-induced wheezing illness occurred predominantly in older patients when compared to RSV patients (P<0.001). RSV infections peaked in the fall and winter followed by peaks of HMPV infection in winter and spring. Eosinophil counts were significantly higher (P<0.01) in RSV patients when compared to HMPV patients. These results show that human metapneumovirus patients exhibit several different clinical and epidemiological characteristics, such as higher proportion of wheezing illness, age and seasonal incidence, and eosinophil counts, when compared to RSV patients.

Local production of inflammatory mediators during childhood parainfluenza virus infection.

OBJECTIVE: To describe the clinical manifestations of parainfluenza virus (PIV) infection and to characterize biochemical markers of PIV disease severity. PATIENTS AND METHODS: We reviewed the medical records of 165 children who had a nasal wash culture positive for PIV at our institution between 1998 and 2008. Nasal wash samples were assayed for 26 inflammatory mediators using Luminex bead proteomics. RESULTS: A total of 153 patients, ages 2 weeks to 12 years, with single virus infection were included in our final analysis. Fifty-two patients were infected with PIV1, 19 with PIV2, 74 with PIV3, and 8 with PIV4. Lower respiratory tract infection (LRTI) was diagnosed in 67 (44%) patients, 21 (14%) had laryngotracheobronchitis, and 49 (32%) had an upper respiratory infection other than laryngotracheobronchitis. LRTI was diagnosed in 54% of patients infected with PIV3, 35% of those infected with PIV1, 26% of those with PIV2, and 50% of those with PIV4. Compared with uninfected control patients, PIV-infected patients had higher nasal wash concentrations of interleukin-6, CX-chemokine ligand 8 (CXCL8 or interleukin-8), CCL3 (macrophage inflammatory protein-1alpha), CCL4 (macrophage inflammatory protein-1beta), CXCL9 (monokine induced by interferon gamma), and CCL5 (regulated upon activation, normal T cell expressed and secreted (RANTES). Patients with LRTI, moderate or severe illness, and PIV 1 or 3 (respirovirus) infection had higher nasal wash concentrations of CXCL8 when compared with patients with upper respiratory infection, mild illness, or PIV 2 and 4 (rubulavirus) infection (P < 0.05). CONCLUSIONS: PIV infection causes a spectrum of illnesses associated with the expression and release of several proinflammatory mediators. Of note, elevated concentrations of CXCL8 in nasal wash samples are associated with more severe forms of PIV disease.

[A guinea pig model of parainfluenza virus type 3 infection-induced acute and postinfectious cough].

OBJECTIVE: To establish a guinea pig model of cough induced by human parainfluenza virus type 3 (PIV3) infection, and to investigate the change of the cough reflex sensitivity (CRS). METHODS: Sixty male SPF guinea pigs were divided into 6 groups (n=10, each), namely, a normal control group, an asthma group and 4 groups of PIV3 inoculation which included post-infection day (PID) 6, 12, 28, and 42. Infected animals were inoculated by intranasal instillation of PIV3 suspension. Control animals were inoculated by uninfected cell culture medium. Asthma animals were sensitized and challenged by ovalbumin. The Buxco system was used to assess cough reflex sensitivity (CRS) elicited by capsaicin and airway hyper-reaction (AHR). Airway inflammation was studied by bronchoalveolar lavage (BAL) cytology and lung histopathology. RESULTS: The CRS of PID 6, 12, 28 and 42 groups was 7.50 (5.25), 7.30 (7.25), 8.40 (9.75) and 8.20 (5.50) Cough counts (CCnt). Compared with 2.50 (3.00) CCnt of the vehicle group, the CRS to capsaicin increased significantly in all the animals with PIV3 inoculation (P value were 0.024, 0.03, 0.011 and 0.008) and peaked in PID 42. There was no significant difference (P=0.18) between 3.90 (1.75) CCnt of the asthma animals and the normal control. Animals of PID 6 showed significantly greater AHR to 2 highest concentrations of methacholine than the normal controls. BAL total cell counts of both the PIV3-inoculated and the asthma animals were significantly higher than those of the normal control, with the number of lymphocytes increased significantly within first 2 weeks after PIV3 inoculation. The lung pathology of PIV3-inoculated animals showed airway inflammation without pneumonia in acute infectious phase. CONCLUSIONS: An animal model of cough induced by PIV3 was created. The CRS of infected guinea pigs increased significantly in both acute and subacute phases of cough. Elevation of CRS may be characteristic of cough caused by virus.