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Structure of the uncleaved ectodomain of the paramyxovirus (hPIV3) fusion protein.

Class I viral fusion proteins share common mechanistic and structural features but little sequence similarity. Structural insights into the protein conformational changes associated with membrane fusion are based largely on studies of the influenza virus hemagglutinin in pre- and postfusion conformations. Here, we present the crystal structure of the secreted, uncleaved ectodomain of the paramyxovirus, human parainfluenza virus 3 fusion (F) protein, a member of the class I viral fusion protein group. The secreted human parainfluenza virus 3 F forms a trimer with distinct head, neck, and stalk regions. Unexpectedly, the structure reveals a six-helix bundle associated with the postfusion form of F, suggesting that the anchor-minus ectodomain adopts a conformation largely similar to the postfusion state. The transmembrane anchor domains of F may therefore profoundly influence the folding energetics that establish and maintain a metastable, prefusion state.

Animals↗

Clinical and epidemiologic characteristics of viral infections in a neonatal intensive care unit during a 12-year period.

BACKGROUND: The incidence of viral infections in patients treated in the neonatal intensive care unit (NICU) is not well-known. We summarized the data of all patients with laboratory-confirmed viral infections admitted at the NICU of our hospital during the period of 1992-2003. OBJECTIVES: To determine the incidence of viral infections among infants hospitalized in a NICU, the associated clinical manifestations and their outcome. METHODS: Retrospective analysis of epidemiologic, virologic and clinical data from infants with proven viral infection. The diagnosis viral infection was confirmed by positive viral culture and/or polymerase chain reaction from clinical samples. RESULTS: Viral infection was confirmed in 51 of 5396 infants (1%) admitted to the NICU; 20 (39%) had an enterovirus and parechovirus (EV/PEV) infection, 15 (29%) a respiratory syncytial virus (RSV) infection, 5 (10%) a rotavirus infection, 3 (6%) a cytomegalovirus (CMV) infection, 2 (4%) an adenovirus infection, 2 (4%) a parainfluenza virus infection, 2 (4%) a herpes simplex virus infection, 1 (2%) a rhinovirus infection and 1 (2%) a rubella virus infection. Three of the infants presented at birth with symptomatic rubella virus, CMV or herpes simplex virus infection. RSV infection developed mostly in hospitalized infants (60%), and 93% of infections occurred during the winter (November-March). The clinical presentations of EV/PEV disease were sepsis-like illness, prolonged seizures in term infants and gastrointestinal disease in preterm infants. RSV, parainfluenza virus, rhinovirus and CMV caused respiratory disease, predominantly in preterm infants. Gastrointestinal disease was seen only in preterm infants with adenovirus, rotavirus or EV/PEV infection. Mortality and serious sequelae were high in patients infected with EV/PEV (10 and 15%, respectively). CONCLUSIONS: The incidence of viral infection in the NICU was 1%. Enteroviral infections were the most frequently diagnosed infections, occurred often in term infants born at home and presented with sepsis-like illness or seizures. Preterm infants hospitalized from birth mainly developed gastrointestinal disease caused by rotavirus and adenovirus infection or respiratory disease caused by RSV, parainfluenza and CMV infection. Enteroviruses were responsible for the highest mortality and development of serious sequelae.

Enterovirus↗

Prevalence of parainfluenza type 1 virus in Lucknow (India).

A total of 568 children suffering from acute respiratory infections were studied from September, 1986 to June, 1988 using indirect immunofluorescence technique to know the frequency of infections caused by parainfluenza viruses 1 and 3. Though sporadic cases of parainfluenza 1 (2.5%) and parainfluenza 3 (3.2%) were seen round the year, and increase in cases of parainfluenza virus type 1 infection was observed only in October, 1987 in Lucknow.

Age Factors↗

Different binding capacities of influenza A and Sendai viruses to gangliosides from human granulocytes.

The structures of gangliosides from human granulocytes were elucidated by fast atom bombardment mass spectrometry and by gas chromatography/mass spectrometry as their partially methylated alditol acetates. In human granulocytes besides GM3 (II3Neu5Ac-LacCer), neolacto-series gangliosides (IV3Neu5Ac-nLcOse4Cer, IV6Neu5Ac-nLcOse4Cer and VI3Neu5Ac-nLcOse6Cer) containing C24:1, and to some extent C22:0; and C16:0 fatty acid in their respective ceramide portions, were identified as major components. In this study we demonstrate that gangliosides from human granulocytes, the second most abundant cells in peripheral blood, can serve as receptors for influenza viruses A/PR/8/34 (H1N1), A/X-31 (H3N2), and a parainfluenza virus Sendai virus (HNF1, Z-strain). Viruses were found to exhibit specific adhesion to terminal Neu5Ac alpha 2-3Gal and/or Neu5Ac alpha 2-6Gal sequences as well as depending on the chain length of ganglioside carbohydrate backbones from human granulocytes, these important effector cells which represent the first line of defence in immunologically mediated reactions.

Carbohydrate Sequence↗

Fluorescence anisotropy of UV-irradiated viruses.

The steady-state fluorescence anisotropy measurements on influenza and parainfluenza viruses, showed no changes in the microviscosity of the viral membranes after exposure to UV-irradiation, when a fluorescent probe was used, but the intrinsic fluorescence of viral proteins presented, under the same experimental conditions, a significant difference of anisotropy behaviour in the two viruses used.

Fluorescence Polarization↗

Role of respiratory viral infection in SIDS: detection of viral nucleic acid by in situ hybridization.

There is considerable evidence suggesting that respiratory viral infection is involved in the genesis of the sudden infant death syndrome (SIDS), with rates of about 20 per cent of SIDS victims compared to about 13 per cent of controls. Since the techniques used previously are prone to under-reporting from autopsy material, non-isotopic in situ hybridization (NISH) has been used to detect viral nucleic acid in lung in SIDS. Forty-five SIDS cases (30 males) were examined (age range 3 weeks-14 months, mean age 3.9 months). Thirty non-SIDS cases (15 males) were also examined (age range 5 weeks-24 months, mean age 9.0 months). Eleven of 45 (24.4 per cent) SIDS cases were positive by NISH compared to 1 of 30 (3.3 per cent) non-SIDS cases (P = 0.012). There were eight cases of adenovirus type 5, two cases of respiratory syncytial virus (RSV), and one case of parainfluenza virus type 2. The one positive control case was adenovirus type 5. Only lung parenchyma was examined here. Additional examination of the upper respiratory tract may increase the number of positive cases.

Adenoviruses, Human↗

Neuraminidase inhibitors as antiviral agents.

The enzyme neuraminidase (NA) is an attractive target for antiviral strategy because of its essential role in the pathogenicity of many respiratory viruses. NA removes sialic acid from the surface of infected cells and virus particles, thereby preventing viral self-aggregation and promoting efficient viral spread; NA also plays a role in the initial penetration of the mucosal lining of the respiratory tract. Random screening for inhibitors has identified only low-affinity and nonselective viral NA inhibitors. Selective, high-affinity inhibitors of influenza virus neuraminidase, zanamivir and oseltamivir, were developed using computer-aided design techniques on the basis of the three-dimensional structure of the influenza virus NA. These drugs were highly efficient in inhibiting replication of both influenza A and B viruses in vitro and in vivo and were approved for human use in 1999. Subsequently, the same structure-based design approach was used for the rational design of inhibitors of the parainfluenza virus hemagglutinin-neuraminidase (HN). One of these compounds, BCX 2798, effectively inhibited NA activity, cell binding, and growth of parainfluenza viruses in tissue culture and in the lungs of infected mice. Clinical reports indicate high efficiency of NA inhibitors for prophylaxis and treatment of influenza virus infection, good tolerance, and a low rate of emergence of drug-resistant mutants. Future experimental and clinical studies should establish the viability of NA inhibitors for the treatment of other respiratory virus infections.

Acetamides↗

Respiratory syncytial virus G and/or SH glycoproteins modify CC and CXC chemokine mRNA expression in the BALB/c mouse.

Chemokine mRNA expression by pulmonary leukocytes following infection of BALB/c mice with two strains of respiratory syncytial virus (RSV) and one strain of parainfluenza virus type 3 (PIV-3) was determined. The results suggest that RSV G and/or SH proteins inhibit early MIP-1alpha, MIP-1beta, MIP-2, MCP-1, and IP-10 mRNA expression. TCA-3 mRNA expression was found to be increased during PIV-3 infection.

Animals↗

Rapid and sensitive detection of respiratory virus infections for directed antiviral treatment using R-Mix cultures.

BACKGROUND: The development of new anti-influenza drugs has led to concerns regarding the impact on healthcare costs if they are used indiscriminately. Restricting their use to proven influenza virus infections has the potential to overcome costly inappropriate therapy. However, conventional culture (CC) does not generate results quickly enough to facilitate the timely initiation of treatment, and rapid detection tests have suboptimal sensitivity. We therefore investigated a new rapid culture system (R-Mix) that contains a mixture of two cell lines and detects respiratory viruses within 24 h. OBJECTIVES: To compare the analytical sensitivity of R-Mix with CC and rapid detection methods, for the detection of influenza and other respiratory viruses. To compare the clinical sensitivity of R-Mix with CC and direct antigen detection for the detection of respiratory viruses in primary and acute care settings. STUDY DESIGN: Stock cultures of influenza virus were titrated and tested by R-Mix, ZstatFlu and FLU OIA. Stock cultures of adenovirus and parainfluenza virus type 3 were titrated and tested by R-Mix and CC. Specimens, which had previously tested positive for influenza viruses, were titrated and tested by R-Mix and CC. In symptomatic patients, the majority of whom were from primary care settings, 124 sequential specimens were tested for influenza viruses by immunofluorescent direct antigen detection and R-Mix. A separate set of 111 sequential specimens, from various symptomatic patient groups, were tested for influenza viruses by CC and R-Mix. Additionally, in acute care patients being surveillance tested during periods of immunosuppression, 155 specimens were tested for respiratory viruses (influenza A and B, parainfluenza 1-3, adenovirus and respiratory syncytial virus (RSV)) by CC and R-Mix. RESULTS: With titrated stock cultures, R-Mix showed an analytical limit of detection of ten infectious virus particles per vial for influenza A, compared with 100,000 particles per test for FLU OIA and 1,000,000 for ZstatFlu. R-Mix also showed a 100-fold greater sensitivity for the detection of influenza A and equivalent sensitivity for the detection of influenza B when compared with CC in titrated known positive specimens. Further, it showed equivalent sensitivity to CC for the detection of adenovirus and parainfluenza virus type 3 in titrated stock cultures. Among prospective specimens from symptomatic patients, the sensitivity of R-Mix, CC and direct antigen detection tests (DAT) for influenza virus detection, was 100, 67 and 66%, respectively, and the specificity was 100, 100 and 98%, respectively. In surveillance specimens from immunosuppressed patients, the sensitivities of R-Mix and CC for respiratory virus detection were equivalent. Moreover, R-Mix results were available within 24 h, and by altering the antibody staining reagents either influenza viruses, or all seven major respiratory viruses, could be detected and distinguished in a single test. CONCLUSIONS: R-Mix is a simple, rapid and sensitive system for the detection of influenza viruses that facilitates the restriction of antiviral drugs to patients with culture-confirmed infections.

Adenoviridae↗

Simian virus 5 is a poor inducer of chemokine secretion from human lung epithelial cells: identification of viral mutants that activate interleukin-8 secretion by distinct mechanisms.

We have compared chemokine secretion from human lung A549 cells infected with simian virus 5 (SV5) with other members of the Rubulavirus genus of paramyxoviruses. High levels of the chemokines interleukin-8 (IL-8) and macrophage chemoattractant protein-1 (MCP-1) were secreted from A549 cells infected with Human parainfluenza virus type 2 (HPIV-2) but not from cells infected with wild-type (WT) SV5. The lack of IL-8 secretion from SV5-infected cells was not due to a global block in all signal transduction pathways leading to IL-8 secretion, since SV5-infected A549 cells secreted IL-8 after stimulation with exogenously added tumor necrosis factor alpha or by coinfection with HPIV-2. A previously described, recombinant SV5 containing substitutions in the shared region of the P/V gene (rSV5-P/V-CPI-) induced IL-8 secretion by a mechanism that was dependent on viral gene expression. By contrast, an SV5 variant isolated from persistently infected cells (Wake Forest strain of Canine parainfluenza virus) induced IL-8 secretion by a mechanism that was largely not affected by inhibitors of viral gene expression. Together, these data demonstrate that SV5 is unusual compared to other closely related paramyxoviruses, since SV5 is a very poor inducer of the cytokines IL-8 and MCP-1. The isolation of two recombinant SV5 mutants that are defective in preventing chemokine induction will allow an identification of mechanisms utilized by WT SV5 to avoid activation of host cell innate immune responses to infection.

Animals↗

Seasonal trends of human parainfluenza viral infections: United States, 1990-2004.

BACKGROUND: Human parainfluenza viruses (HPIVs) are important causes of upper and lower respiratory tract illness among children and adults. METHODS: We describe seasonal trends for individual HPIV serotypes and respiratory syncytial virus in the United States using data on the percentage of specimens with positive test results reported to the National Respiratory and Enteric Viruses Surveillance System during the period 1990-2004. Onset and conclusion dates for peaks in activity were determined with the Early Aberration Reporting System's cumulative sum method C2 by detecting periods when the number of positive HPIV test results was significantly greater than that observed for preceding weeks for each serotype. RESULTS: During the study period, increases in the percentage of positive HPIV-3 and HPIV-2 test results occurred annually during April-June and October-November, respectively. Increases in the percentage of positive HPIV-1 test results occurred biennially during September-December during odd-numbered years. During years when HPIV-1 was not circulating, more HPIV-3 activity was reported, either as a longer spring season or as a second smaller period of increased activity noted in the fall. Seasonal peaks in respiratory syncytial virus activity occurred annually during November-April. CONCLUSIONS: We provide a national perspective for HPIV activity during the 15-year study period and demonstrate distinct seasonal peaks in activity for HPIV-1, HPIV-2, and HPIV-3. In addition, our data suggest that there is an interaction between HPIV-3 and HPIV-1 activity, which may have implications in future prevention strategies.

Adult↗

Evaluation of R-Mix shell vials for the diagnosis of viral respiratory tract infections.

Respiratory viruses cause significant morbidity and mortality. The management of these infections can be improved by a rapid diagnosis and administration of available virus-specific therapy. The goal of this study was to compare R-Mix, an engineered tissue monolayer for rapid shell vial (SV) diagnosis of viral respiratory infections, with conventional tissue culture (TC) and conventional respiratory SV (primary rhesus monkey kidney (RhMK) and Hep2 monolayers). The primary outcome measure was sensitivity for detection of influenza A and B, respiratory syncytial virus, parainfluenza 1-3, and adenovirus. The study was performed in two phases: (1) the three methods were compared using 250 nasal washes from children with lower respiratory tract infections; (2) a modified R-Mix SV harvesting schedule (SV were harvested at 24 and 120 h) was compared with TC and conventional RhMK/Hep2 SV using 311 respiratory specimens. A total of 110 viruses were identified in the first and 55 in the second phase. Diagnostic accuracies of R-Mix harvested at 24, 48, and 120 h were 98%, whereas for TC varied between 99 and 100%, and for RhMK/Hep2 SV between 98 and 99%. Sensitivities of R-Mix harvested at 24, 48, and 120 h were 26, 75, and 47%, respectively, whereas for TC varied between 60 and 94%, and for RhMK/Hep2 SV between 62 and 85%. R-Mix harvested at 48 h represent a valuable substitute for RhMK/Hep2 SV because they have comparable sensitivities and diagnostic accuracies, but R-Mix offers several technical advantages. In contrast, R-Mix harvested at 24h did not seem a very useful diagnostic tool. The utility of R-Mix harvested at 120 h, which accelerated the diagnosis of 16% of positive specimens in study phase 2, needs further investigation.

Adenoviruses, Human↗

WHO respiratory disease survey in children: a serological study.

This paper is a report on the first (serological) phase of a study organized by WHO in collaboration with the WHO International Reference Centre for Respiratory Virus Diseases other than Influenza in Bethesda, Md., USA, to define the viral etiology of severe respiratory infections in children, particularly in tropical areas. Paired sera from 528 children up to 5 years old admitted to hospital with severe respiratory illness of probable viral etiology were collected in 10 countries and sent frozen to the International Reference Centre, where standard complement-fixation tests were made for the following agents: parainfluenza virus types 1, 2 and 3, influenza virus types A and B, adenoviruses, respiratory syncytial virus, Mycoplasma pneumoniae, Coxiella burneti and psittacosis-ornithosis.Some 41% of paired sera showed rising antibody titres for one or more of these agents, multiple infections being observed in 8%. In most of the countries the pattern of infection was similar. RS virus was the most important respiratory tract pathogen of early life, particularly in the first year of life and in cases of bronchiolitis and pneumonia; the parainfluenza viruses were next in importance, particularly in cases of croup, but, in contra-distinction to RS virus infections, they were commoner in older children. Influenza, adenoviruses, and M. pneumoniae were of moderate importance, and C. burneti and the psittacosis-ornithosis agents were relatively rare. This pattern is similar to that which has been observed in temperate climates.

Africa↗

An improved method for the recovery of recombinant paramyxovirus vaccine candidates suitable for use in human clinical trials.

We describe a method for the generation of clinical grade, live-attenuated vaccines in Vero cells entirely from cDNA plasmids. The entire electroporation procedure can be completed in less than 15 minutes and this is a significant improvement over previous lipid or electroporation based transfection techniques that also involve a heat-shock step. Importantly, the virus preparations can be generated with a minimal use of animal product derived materials, an important consideration for a vaccine candidate that is to be tested in humans. Since it is likely that all live-attenuated parainfluenza virus and pneumovirus vaccines in the future will be generated using reverse genetics, this simplified method provides guidance on how this can be achieved.

Animals↗

Polarity and fusion of JAR choriocarcinoma cells as assessed by enveloped viral glycoproteins.

Placental trophoblasts are epithelial cells which undergo physiological fusion and generate syncytia. In this study, a placental choriocarcinoma cell line JAR was infected with two enveloped viruses, Parainfluenza type 3 (P3) or vesicular stomatitis virus (VSV). Both viruses possess a fusion glycoprotein known to be able to induce polykaryon formation in nonpolarized cells. The P3 virus fusion protein was localized on the apical as well as on the basal plasma membrane domains of the infected JAR cells. Infection of the JAR cell monolayer with P3 virus, whose fusion protein is active at pH 7.0, resulted in syncytia formation. Furthermore, the actin ring structure surrounding individual cells disappeared during the P3 virus induced cell-cell fusion. On the contrary, the VSV glycoprotein was found preferentially on the apical plasma membrane domain. To activate the VSV fusogen, the cells were subjected to pH 5.0. However, no syncytia formation peculiar to VSV-infected fibroblasts was observed, and the actin ring structures remained intact. We conclude that in JAR cells the VSV fusion protein exhibits a polarized expression while the P3 virus fusion glycoprotein is distributed between the two membrane domains. Our results suggest that an apically situated fusogen is not sufficient to mediate cell-cell fusion of JAR cells.

Animals↗

Antigenic and structural properties of a paramyxovirus simian virus 41 (SV41) reveal a close relationship with human parainfluenza type 2 virus.

Seven structural component proteins of a paramyxovirus simian virus 41 (SV41) were identified with the aid of monoclonal antibodies prepared against SV41 and human parainfluenza type 2 virus (PIV2). The nucleoprotein is antigenically very close to that of PIV2, while it is comparatively far from that of simian virus 5 (SV5). The hemagglutinin-neuraminidase (HN) protein showed no immunological relationship to either of the HN proteins of PIV2 or SV5. The amino acid sequence of the SV41 HN protein was deduced from the nucleotide sequence of its HN gene and revealed that the SV41 HN is unexpectedly close to the PIV2 HN (61.2% identity in amino acid sequence), while the SV5 HN showed only 48.3% identity with the PIV2 HN. The SV41 HN is also related to the SV5 HN (51.3% identity); thus, the SV41 HN is phylogenetically situated between the PIV2 and SV5 HNs. These results indicate that SV41 is the virus closest to PIV2 at present.

Amino Acid Sequence↗