Age-dependent replication of respiratory syncytial virus in the cotton rat

Despite the documented disease burden of respiratory syncytial virus (RSV) in the elderly, little is known about the underlying risk factors or pathogenesis of RSV in a geriatric population. This report describes an age-dependent change of RSV clearance in the lung and nose of the cotton rat. Six days postinfection with RSV, lung and nose viral titers were significantly higher in all older age groups as compared with 4- to 6-week old cotton rats (P < 0.05). When comparing the 4- to 6-week old animals to the 15- to 16-month old animals 6 days postinfection, there was over an 800- and 100-fold increase in lung and nose viral titers, respectively. The cotton rat may prove to be a useful model in eliciting mechanisms of severe RSV disease in the elderly.

Quantities of infectious virus and viral RNA recovered from sheep and cattle experimentally infected with foot-and-mouth disease virus O UK 2001

The profiles of virus production and excretion have been established for sheep experimentally infected with the UK 2001 strain of foot-and-mouth disease (FMD) virus by inoculation and by direct and intensive contact. Virus replicated rapidly in the inoculated sheep, from which a peak infectivity of airborne virus of 10(4.3) TCID(50) per sheep per 24 h was recovered. Around 24 h later, contact-infected sheep excreted airborne virus maximally. Similar amounts of airborne virus were recovered from cattle. The excretion of virus by the sheep under these conditions fell into three phases. First, a highly infectious period of around 7-8 days. Second, a period of 1-3 days soon afterwards when trace amounts of viral RNA were recovered in nasal and rectal swabs. Third, at 4 weeks after exposure, the demonstration, by tests on oesophageal-pharyngeal samples, that 50% of the sheep were carriers. The implications of the results and the variable role that sheep may play in the epidemiology of FMD are discussed.

The vaccinia virus N1L protein is an intracellular homodimer that promotes virulence

The vaccinia virus (VV) N1L gene encodes a protein of 14 kDa that was identified previously in the concentrated supernatant of virus-infected cells. Here we show that the protein is present predominantly (>90%) within cells rather than in the culture supernatant and it exists as a non-glycosylated, non-covalent homodimer. The N1L protein present in the culture supernatant was uncleaved at the N terminus and was released from cells more slowly than the VV A41L gene product, a secreted glycoprotein that has a conventional signal peptide. Bioinformatic analyses predict that the N1L protein is largely alpha-helical and show that it is conserved in many VV strains, in other orthopoxviruses and in members of other chordopoxvirus genera. However, database searches found no non-poxvirus proteins with significant amino acid similarity to N1L. A deletion mutant lacking the N1L gene replicated normally in cell culture, but was attenuated in intranasal and intradermal murine models compared to wild-type and revertant controls. The conservation of the N1L protein and the attenuated phenotype of the deletion mutant indicate an important role in the virus life-cycle.

Prevalence of swine influenza virus subtypes on swine farms in the United States

Serologic and virologic prevalence of infection with different swine influenza virus (SIV) subtypes was investigated using swine sera, nasal swabs and lung samples that had been submitted for a diagnosis to the Minnesota Veterinary Diagnostic Laboratory. A total of 111,418 pig sera were tested for SIV antibody between 1998 and 2000, and 25,348 sera (22.8%) were found to be positive by the hemagglutination inhibition (HI) test. Of the positive samples, 16,807 (66.7%) and 8,541 (33.7%) had antibody to H1 and H3 subtypes, respectively. Between January 1998 and May of 2001, a total of 3,561 nasal swabs or lung samples were examined for the presence of SIV, and SIV was isolated from 1,124 samples (31.7%). Of these isolates, 869 (77.3%) and 255 (22.7%) were subtyped as H1 and H3, respectively, by the HI method. For further characterization, 120 SIV isolates each from 1998 to 2001 were randomly selected from a culture collection and their hemagglutinin (HA) and neuraminidase genes examined by reverse transcription-PCR and sequencing. Of the 480 isolates, 322 (67.1%), 22 (4.6%) and 129 (26.9%) were subtyped as H1N1, H1N2 and H3N2, respectively. The remaining 7 samples (1.5%) were found to contain both H1N1 and H3N2 viruses. The SIV H1N2 subtype was isolated from 1, 8, and 13 samples in 1999, 2000, and 2001, respectively. The 22 H1N2 isolates originated from 9 different states of the United States. Genetic screening of the HA genes of 12 selected H1N2 isolates showed that 8 of them had a close phylogenetic relationship with the Indiana isolate of H1N2 (A/Swine/Indiana/9K035/99), while 4 isolates were closely related to classical SIV H1N1.

Evaluation of the portable Cepheid SmartCycler real-time PCR machine for the rapid diagnosis of foot-and-mouth disease

The ability of the portable Cepheid SmartCycler real-time PCR machine to detect foot-and-mouth disease (FMD) virus sensitively and accurately was evaluated by comparing the results of the analyses of nasal swab and serum samples from experimentally infected animals with those obtained from the real-time PCR assay currently in use in the laboratory. The results indicated that the ability of the machine to detect viral RNA is greatly affected by the PCR reagents used for the assay. When it was used with PCR beads it was unable to detect weakly positive samples, but when TaqMan core reagents were used for the assay, its sensitivity was significantly increased. The machine could be used for the laboratory-based detection of FMD; however, as with all assays, significant optimisation of assay conditions as well as solid validation of the technique is required.

A randomized, double-blind, placebo-controlled trial of dexamethasone in severe respiratory syncytial virus (RSV) infection: effects on RSV quantity and clinical outcome

Forty-one previously healthy children <2 years of age who required mechanical ventilation for respiratory syncytial virus (RSV) infection were randomized to receive dexamethasone (0.5 mg/kg; n=22) or saline placebo (n=19) intravenously every 12 h for 4 days. RSV quantity was measured by quantitative plaque assay in fresh tracheal and nasal aspirates obtained at intervals of 24+/-3 h on days 0, 1, 2, 5, and 7 following entry. Analysis by linear mixed-effects modeling demonstrated a significantly greater decline in mean tracheal RSV quantity in the placebo group than in the dexamethasone group from day 0 to day 1 (0.82 vs. 0.21 log pfu/mL; P=.01) and from day 0 to day 2 (1.45 vs. 0.53 log pfu/mL; P=.03). No differences were found between groups in nasal RSV quantity, white blood cell counts in tracheal or nasal aspirates, serum neutralizing antibody titers during convalescence, or duration of mechanical ventilation, intensive care unit stay, or hospital stay.

First evidence of porcine circovirus type 2 (PCV-2) infection of pigs in the Czech Republic by semi-nested PCR

Three oligonucleotide primers for semi-nested polymerase chain reaction (PCR) were designed according to already published sequences of porcine circovirus types 1 (PCV-1) and 2 (PCV-2) isolates. These primers were used to detect PCV-2 DNA. A positive amplification reaction was visualized from a DNA suspension containing as few as 10 copies of virus DNA. In total. 77 samples of inguinal lymph nodes and nasal swabs from pigs in the Czech Republic were used to detect the virus. Thirty-seven of them were positive for PCV-2 DNA. In order to confirm specificity of the PCR reaction, seven DNA fragments were sequenced. Czech PCV sequences were found to have a 92-97% homology with other known PCV-2 strains and only 80-83% homology with PCV-1 strains.

Cultures of equine respiratory epithelial cells and organ explants as tools for the study of equine influenza virus infection

Equine nasal turbinate epithelial cells and tracheal rafts were maintained with sustained viability in culture. Both types of culture supported productive replication of equine influenza virus (equine-2, subtype H3N8) and cell death occurred through apoptosis following viral infection. Thus, primary respiratory epithelial cell and organ cultures of equine origin may be valuable as alternatives to the intact animal for studying the virus-host interaction of equine respiratory viruses including influenza.

Contribution of the human parainfluenza virus type 3 HN-receptor interaction to pathogenesis in vivo

The envelope of human parainfluenza virus type 3 (HPF3) contains two viral glycoproteins, the hemagglutinin-neuraminidase (HN) protein and the fusion (F) protein. In a previous study, highly fusogenic variant HPF3 viruses were isolated, including two, C-0 and C-22, that exhibit increased avidity for sialic acid receptors due to single amino acid changes in the HN protein and one, C-28, that has decreased neuraminidase activity relative to that of the wild type (wt) and is delayed in the release of virus particles into the supernatant fluid. These variants form very large plaques and destroy a cell monolayer more rapidly than does wt HPF3 in cell culture. These variant viruses allowed us to formulate hypotheses about the roles of HN in pathogenesis. We investigated the behavior of wt HPF3 and the three variant viruses in the cotton rat model. In the cotton rat, there was no delayed clearance of any of the variant viruses compared to that of the wt. The variant plaque morphology was preserved in vivo, and there was no reversion to the wt phenotype in the infected animals. In spite of a slight advantage of wt virus in viral titer, there were no differences in the severities of peribronchiolitis between wt viruses and the variants. However, there were marked differences in severities in alveolitis and interstitial pneumonitis when each of the three variants was compared to the wt, with the variants causing enhanced disease. Thus, despite similar or lower viral titers and similar clearance rates, the variants caused more extensive disease in the lung. The results show that mutations in HN conferring altered fusion properties in cell culture also confer striking differences in the ability of HPF3 to cause extensive disease in the cotton rat lung and that this effect is dissociated from any effect on viral replication.

Effect of experimental influenza A infection on systemic immune and inflammatory parameters in allergic and nonallergic adult subjects

BACKGROUND

The economic impact and medical complication rate of viral upper respiratory infections are well documented, but many of the physiologic, inflammatory, and immune responses to respiratory viruses have only recently been investigated. A previous study demonstrated differential systemic immune and inflammatory responses in allergic rhinitis (AR) and nonallergic rhinitis (NAR) subjects during experimental infection with rhinovirus-39.

OBJECTIVE

The purpose of this study was to compare selected systemic immune and inflammatory responses to experimental influenza A virus (FLU) challenge in seronegative AR and NAR subjects.

METHODS

Peripheral blood was obtained at baseline (study day 0) and 3, 6, 18, and 31 days after intranasal FLU challenge and assayed for leukocyte histamine release, serum immunoglobulins, and plasma histamine.

RESULTS

All subjects were infected, as manifested by viral shedding in nasal secretions and/or seroconversion. FLU infection induced decreases in spontaneous leukocyte histamine release and increases in anti-immunoglobulin E-induced leukocyte histamine release, which were evident at least 1 month after infection, but caused no significant changes in serum immunoglobulins or plasma histamine. There were no differences between AR and NAR subjects for any of the study parameters.

CONCLUSIONS

The results show that intranasal challenge with FLU induces changes in leukocyte histamine release, but not other systemic immune and inflammatory responses.

The discovery of RFI-641 as a potent and selective inhibitor of the respiratory syncytial virus

The design and synthesis of a new potent and selective inhibitor of the respiratory syncytial virus are described. This compound, RFI-641, emerged from analysis of the structure-activity relationship in a series of biphenyl triazine anionic compounds possessing specific anti-RSV activity. The key synthetic step involves coupling of diaminobiphenyl 11 with two equivalents of chlorotriazine 10 under microwave conditions. RFI-641 inhibited RSV in vitro and in vivo models.

Effectiveness of oseltamivir in preventing influenza in household contacts: a randomized controlled trial

CONTEXT

Influenza virus is easily spread among the household contacts of an infected person, and prevention of influenza in household contacts can control spread of influenza in the community.

OBJECTIVE

To investigate the efficacy of oseltamivir in preventing spread of influenza to household contacts of influenza-infected index cases (ICs).

DESIGN AND SETTING

Randomized, double-blind, placebo-controlled study conducted at 76 centers in North America and Europe during the winter of 1998-1999.

PARTICIPANTS

Three hundred seventy-seven ICs, 163 (43%) of whom had laboratory-confirmed influenza infection, and 955 household contacts (aged >/=12 years) of all ICs (415 contacts of influenza-positive ICs).

INTERVENTIONS

Household contacts were randomly assigned by household cluster to take 75 mg of oseltamivir (n = 493) or placebo (n = 462) once daily for 7 days within 48 hours of symptom onset in the IC. The ICs did not receive antiviral treatment.

MAIN OUTCOME MEASURE

Clinical influenza in contacts of influenza-positive ICs, confirmed in a laboratory by detection of virus shedding in nose and throat swabs or a 4-fold or greater increase in influenza-specific serum antibody titer between baseline and convalescent serum samples.

RESULTS

In contacts of an influenza-positive IC, the overall protective efficacy of oseltamivir against clinical influenza was 89% for individuals (95% confidence interval [CI], 67%-97%; P<.001) and 84% for households (95% CI, 49%-95%; P<.001). In contacts of all ICs, oseltamivir also significantly reduced incidence of clinical influenza, with 89% protective efficacy (95% CI, 71%-96%; P<.001). Viral shedding was inhibited in contacts taking oseltamivir, with 84% protective efficacy (95% CI, 57%-95%; P<.001). All virus isolates from oseltamivir recipients retained sensitivity to the active metabolite. Oseltamivir was well tolerated; gastrointestinal tract effects were reported with similar frequency in oseltamivir (9.3%) and placebo (7.2%) recipients.

CONCLUSION

In our sample, postexposure prophylaxis with oseltamivir, 75 mg once daily for 7 days, protected close contacts of influenza-infected persons against influenza illness, prevented outbreaks within households, and was well tolerated.

Treatment of lethal vaccinia virus respiratory infections in mice with cidofovir

Intranasal infection of BALB/c mice with the WR strain of vaccinia virus leads to pneumonia, profound weight loss and death. Five days after intranasal inoculation, virus from untreated mice was recovered from 11 organs, tissues and whole blood. The highest titres [>10(8) plaque forming units (pfu)/g] were in lungs and nose/sinus tissue, with about 10(7) pfu/g in spleen and blood. Seven other organs contained 30- to > or = 50-fold lower amounts of virus. Mice infected with the related cowpox virus (for comparative purposes) had the majority of virus located in the respiratory tract. The vaccinia mouse model was used to study the efficacy of cidofovir treatments on the infection. Subcutaneous injections of 30 or 100 mg/kg/day, given on days 1 and 4 after virus challenge, reduced mortality by 60-100%. However, lung virus titres on days 2-5 were reduced no more than 10-fold by these treatments. A moderate improvement in drug efficacy occurred with daily treatments for 5 days. The efficacy of cidofovir also increased as the virus challenge dose decreased, where subcutaneous or intraperitoneal treatment routes showed similar degrees of protection. Although it has been known for many years that the WR strain of vaccinia virus can cause lethal infections by intranasal route, its application to antiviral therapy represents a new model for studying anti-orthopoxvirus agents.

Cross-protection studies between respiratory and calf diarrhea and winter dysentery coronavirus strains in calves and RT-PCR and nested PCR for their detection

A 1-step RT-PCR assay, targeting a 730 bp fragment of the nucleocapsid (N) gene of bovine coronavirus (BCV), and a nested PCR assay, targeting a 407 bp fragment of the N gene, were developed to detect BCV in nasal swab and fecal samples of calves experimentally exposed to BCV. Both 1-step RT-PCR and nested PCR recognized cell culture passaged isolates of 10 bovine respiratory coronavirus (BRCV), 5 calf diarrhea (CD) and 8 winter dysentery (WD) strains of BCV, but not transmissible gastroenteritis coronavirus or bovine rotavirus. The sensitivity of the 1-step RT-PCR and nested PCR was compared to that of an antigen-capture ELISA. The lowest detection limit of the 1-step RT-PCR and nested PCR as determined by using tenfold serial dilutions of the BRCV 255 and 440 strains in BCV negative nasal swab suspensions from preexposure gnotobiotic calves was 2 x 10(4) and 2 x 10(2) TCID50/0.1 ml for each strain, respectively. The lowest detection limit of the antigen-capture ELISA as determined by using the same serially diluted samples was 1 x 10(6) TCID50/0.1 ml for each strain. Therefore, the 1-step RT-PCR and nested PCR assays were 50 and 5000 times, respectively more sensitive than the antigen-capture ELISA to detect BRCV in nasal swab suspensions. To investigate in vivo cross-protection between the BRCV and CD or WD strains of BCV and to detect nasal and fecal shedding of BCV using the 1-step RT-PCR, nested PCR and antigen-capture ELISA, 6 colostrum-deprived and two gnotobiotic calves were inoculated with a BRCV, a CD or a WD strain of BCV and then challenged 3-4 weeks later with either BRCV, CD or WD strains of BCV. All calves developed diarrhea after inoculation and BCV antigen (ELISA) or RNA (RT-PCR) was detected in the diarrheic fecal samples or the corresponding nasal swab samples. In addition, low amounts of BCV were also detected only by nested PCR in the fecal and nasal swab samples before and after diarrhea. No respiratory clinical signs were observed during the entire experimental period, but elevated rectal temperatures were detected during diarrhea in the BCV-inoculated calves. All calves recovered from infection with the BRCV, CD, or WD strains of BCV were protected from BCV-associated diarrhea after challenge exposure with either a heterologous or homologous strain of BCV. However, all calves challenged with heterologous BCV strains showed subclinical BCV infection evident by detection of nasal and fecal shedding of BCV RNA detected only by nested PCR. Such results confirm field and experimental data documenting reinfection of the respiratory and enteric tracts of cattle, suggesting that, in closed herds, respiratory or enteric tract reinfections may constitute a source of BCV transmissible to cows (WD) or neonatal or feedlot calves. In addition, the present 1-step RT-PCR and nested PCR assays were highly sensitive to detect BCV in nasal swab and fecal specimens. Therefore, these assays should be useful to diagnose BCV infections in calves and adult cows.

Evaluation of BioStar FLU OIA assay for rapid detection of influenza A and B viruses in respiratory specimens

BACKGROUND

Demand for the rapid diagnosis of influenza infections has increased with the advent of the availability of neuraminidase antiviral therapy for influenza A and B. Several rapid assays that detect both influenza A and B are now available.

OBJECTIVES

In this study we compared the performance of the BioStar FLU OIA assay to Bartels Viral Respiratory Screening and Identification Kit (Bartels Inc., Issaquah, WA), and cell culture.

STUDY DESIGN

A total of 145 patient specimens for influenza virus detection submitted in either viral transport medium or in sterile containers were evaluated by the three methods. Specimen types included nasal washings, nasal swabs, sputum, throat swabs, and bronchial alveolar lavage (BAL) fluids.

RESULTS

Fifty six positive specimens were identified based on culture and/or DFA. Of these, 30 specimens were positive by the OIA assay for an overall sensitivity of 54%. The OIA assay detected 48% (n = 21) of the 44 culture positive specimens and 81% (n = 29) of the 36 DFA positive specimens. Eighty six of the 89 culture/DFA negative samples were negative by the OIA assay (97% specificity). Analysis of the OIA assay sensitivity from samples submitted in M4 transport medium or in sterile containers revealed that M4 transport medium does not reduce the sensitivity of the OIA assay. Fifteen of the 27 positive samples submitted in M4 transport medium were positive by the OIA assay (56% sensitivity) compared to 15 of 29 positive samples transported in sterile containers (52% sensitivity). Twelve specimens were either culture and/or DFA positive for viruses other than influenza, but negative by the OIA assay, suggesting that there was no cross reactivity of the OIA assay with the other virus types recovered in this study.

CONCLUSIONS

The overall excellent specificity of the BioStar FLU OIA allows for treatment of positive patients for influenza, however, a negative result should be confirmed by DFA and culture.

Genotypic stability of cold-adapted influenza virus vaccine in an efficacy clinical trial

An investigational live influenza virus vaccine, FluMist, contains three cold-adapted H1N1, H3N2, and B influenza viruses. The vaccine viruses are 6/2 reassortants, in which the hemagglutinin (HA) and neuraminidase (NA) genes are derived from the circulating wild-type viruses and the remaining six genes are derived from the cold-adapted master donor strains. The six genes from the cold-adapted master donor strains ensure the attenuation, and the HA and NA genes from the wild-type viruses confer the ability to induce protective immunity against contemporary influenza strains. The genotypic stability of this vaccine was studied by employing clinical samples collected during an efficacy trial. Viruses present in the nasal and throat swab specimens and in supernatants after culturing the specimens were detected and subtyped by multiplex reverse transcriptase (RT)-PCR. Complete genotypes of these detected viruses were determined by a combination of RT-PCR and restriction fragment length polymorphism, multiplex RT-PCR and fluorescent single-strand conformation polymorphism, and nucleic acid sequencing analysis. The FluMist vaccine appeared to be genotypically stable after replication in the human host. All viruses detected during the 2-week postvaccination period were shed vaccine viruses and had maintained the 6/2 genotype.

Comparison of four clinical specimen types for detection of influenza A and B viruses by optical immunoassay (FLU OIA test) and cell culture methods

Although laboratory diagnosis of respiratory viruses has been widely studied, there is a relative insufficiency of literature examining the impact of specimen type on the laboratory diagnosis of influenza A and B. In a clinical study comparing the FLU OIA test with 14-day cell culture, clinical specimens from nasopharyngeal swabs, throat swabs, nasal aspirates, and sputum were obtained from patients experiencing influenza-like symptoms. A total of 404 clinical specimens were collected from 184 patients. Patients were defined as influenza positive if the viral culture of a specimen from any sample site was positive. Patients were defined as influenza negative if the viral cultures of specimens from all sample sites were negative. By this gold standard, culture and FLU OIA test results for each sample type were compared. For each of the four specimen types, the viral culture and FLU OIA test demonstrated equal abilities to detect the presence of influenza A or B virus or viral antigen. Sputum and nasal aspirate samples were the most predictive of influenza virus infection. Throat swabs were the least predictive of influenza virus infection, with both tests failing to detect influenza virus in nearly 50% of the throat samples studied.

Clinical activity of pleconaril in an experimentally induced coxsackievirus A21 respiratory infection

A randomized, double-blind study assessed the efficacy and safety of pleconaril, a novel antiviral drug with broad-spectrum activity against picornaviruses, in the treatment of 33 adults with an experimentally induced viral respiratory infection. Subjects received either pleconaril 200 mg twice daily (initial dose of 400 mg) or placebo for 7 days. Fourteen hours after receiving the initial dose of either pleconaril or placebo, subjects were inoculated intranasally with 100 plaque-forming units of coxsackievirus A21. Results revealed statistically significant reductions in viral shedding in nasal secretions (P<.001), nasal mucus production (P=.004), and total respiratory illness symptom scores (P=.013) in pleconaril-treated as compared with placebo-treated subjects. The most common adverse events were nausea and abdominal pain. These data support the safety and efficacy of pleconaril in decreasing the signs and symptoms and viral shedding associated with a viral respiratory infection.

Use of the oral neuraminidase inhibitor oseltamivir in experimental human influenza: randomized controlled trials for prevention and treatment

CONTEXT

Influenza virus neuraminidase is thought to be essential for virus replication in humans; however, to date, available neuraminidase inhibitors are limited to zanamivir, which is topically administered.

OBJECTIVE

To determine the safety, tolerability, and antiviral activity of oral neuraminidase inhibitor oseltamivir (GS4104/Ro64-0796) for prevention and the early treatment of influenza in experimentally infected humans.

DESIGN

Two randomized, double-blind, placebo-controlled trials conducted between June and July 1997.

SETTING

Individual hotel rooms; 2 large US university medical schools.

PARTICIPANTS

A total of 117 healthy adult volunteers (aged 18-40 years; median age, 21 years) who were susceptible (hemagglutination-inhibition antibody titer < or =1:8).

INTERVENTIONS

All subjects were inoculated intranasally with influenza A/Texas/36/91 (H1N1) virus. For the prophylaxis study, oral oseltamivir (100 mg once daily [n = 12], 100 mg twice daily [n = 12], or matching placebo [n = 13], starting 26 hours before virus inoculation) was administered. For the treatment study, the same drug was given (20 mg, 100 mg, or 200 mg twice daily, 200 mg once daily, or matching placebo [n = 16], in each group starting 28 hours after inoculation). All regimens were continued for 5 days.

MAIN OUTCOME MEASURES

Comparing placebo groups with pooled treatment groups, for prophylaxis, outcomes included frequency of infection and viral shedding; for treatment, viral shedding in titers.

RESULTS

In the prophylaxis study, 8 (67%) of 12 placebo and 8 (38%) of 21 oseltamivir recipients became infected (P = .16; efficacy, 61%); 6 (50%) placebo compared with 0 oseltamivir recipients shed virus (P<.001; efficacy, 100%), and 33% of placebo but no oseltamivir recipient had infection-related respiratory illness (P<.01). Among infected subjects in the treatment study (n = 69), the viral titer area under the curve of the combined oseltamivir groups (n = 56) was lower (median [interquartile range [IQR]], 80 [23-151] vs 273 [79-306] log10 tissue culture-infective doses50 per milliliter x hour; P = .02) than the placebo group (n = 13), and the median (IQR) duration of viral shedding with therapy was reduced from 107 (83-131) to 58 (35-59) hours (P = .003). Oseltamivir treatment also reduced symptom scores (median [IQR] score-hours, 225 [97-349] vs 400 [189-645]; P = .05), and nasal proinflammatory cytokine levels. Transient mild to moderate nausea after dosing was observed in 15 (17%) of 88 oseltamivir and 2 (7%) of 29 placebo recipients (95% confidence interval for difference, -11% to 68%), which was largely prevented by ingestion with food.

CONCLUSIONS

In these trials, prophylaxis and early treatment with oral oseltamivir were both associated with significant antiviral and clinical effects in experimental human influenza.

Community study using a polymerase chain reaction panel to determine the prevalence of common respiratory viruses in asthmatic and nonasthmatic children

We developed a sensitive polymerase chain reaction (PCR) panel, suitable for the detection of seven common respiratory viruses, to study the prevalence of viruses in nasal swabs obtained from clinically stable asthmatic children (n = 21), non-physician diagnosed asthmatic children with exercise-induced bronchoconstriction (EIB) (n = 16), and nonasthmatic, non-EIB controls (n = 33). The PCR panel detected viruses in 43/70 (61.4%) specimens but there were no significant differences in prevalence of these viruses between the three groups of children. These results indicate that clinically stable asthmatic and nonasthmatic children frequently harbor viruses in the upper respiratory tract.

Effectiveness of RSVIG prophylaxis and therapy of respiratory syncytial virus in an immunosuppressed animal model

Respiratory syncytial virus (RSV) has emerged as a leading cause of pneumonia, with high mortality, in bone marrow transplant (BMT) recipients, as well as in other profoundly immunocompromised patients, such as myelosuppressed adults with leukemia. We tested the efficacy of immunoglobulin with high anti-RSV neutralizing antibody levels (RSVIG) for prophylaxis and therapy of RSV infection in cotton rats undergoing prolonged immunosuppression with cyclophosphamide. These animals experience persistent infection, a model which is similar to the disease seen in post-BMT humans. Both prophylaxis and therapy reduced pulmonary viral replication over 500-fold to nearly undetectable levels. In animals receiving continual immunosuppression, the use of multiple therapeutic doses of RSVIG was able to prevent rebound viral replication, though virus was not completely eliminated.

Comparative analysis of Epstein-Barr virus gene polymorphisms in nasal T/NK-cell lymphomas and normal nasal tissues: implications on virus strain selection in malignancy

Whether particular Epstein-Barr virus (EBV) strains are preferentially selected in malignant diseases remains controversial. Assessment of the importance of strain variation in the pathogenicity of EBV has been hampered principally by the lack of accurate data on the prevalence of virus variants in the normal population. To clarify this issue, a detailed comparative analysis of the EBV genomes contained in normal nasal and nasopharyngeal mucosal tissues and in nasal T/NK-cell lymphoma, which originates at these anatomic sites, was carried out by PCR amplification across the 30-bp deletion and the 33-bp repeat loci in the LMP1 gene and the type-specific polymorphic loci in the EBNA2 and EBNA3C genes and by sequence analysis of the 3' C-terminal region of the LMP1 gene. Whilst the majority of EBV strains in either normal or tumour tissues were type 1 viruses with similar numbers of LMP1 repeats, a marked predominance of LMP1 deletion (del-LMP1) over non-deleted/wild-type LMP1 (wt-LMP1) variants was observed in nasal T/NK-cell lymphoma. Although del-LMP1 variants were also prevalent in the normal carriers of our population, wt-LMP1 was detected at a significantly higher frequency in normal vs. tumour tissues (p = 0.036). More critically, wt-LMP1 variants were found frequently in mixed infection with del-LMP1 variants in the normal carriers. Sequence analysis identified 2 major del-LMP1 (and several wt-LMP1) variants containing signatory nucleotide changes in relation to the prototype B95-8 sequence in both normal and neoplastic nasal tissues. Together, our data provide strong evidence for a selection mechanism for del-LMP1 over the wt-LMP1 variants in tumours.

Investigation of effects of anesthesia and age on aspiration in mice through LacZ gene transfer by recombinant E1-deleted adenovirus vectors

To examine the role of disturbed upper airway reflexes in aspiration, we administered 20 microliters of the adenovirus (Ad) vector Ad-CMV-LacZ or 20 microliters of phosphate buffered saline (PBS) intranasally to C57 black mice. We investigated expression of the LacZ gene by this Ad vector in the nostrils of each mouse, with or without anesthesia. Under anesthesia, LacZ gene expression was detected in the lungs of every mouse given the Ad vector. However, no LacZ gene expression was found in the trachea or lungs of mice given the Ad vector without anesthesia. In mice given PBS or wild-type adenovirus transnasally during anesthesia, there was no LacZ gene expression in the nostrils, trachea, or lungs, suggesting that with 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) staining, blue-stained cells indicated transferred LacZ gene expression. These results suggested that aspiration of intranasal solution into lower airways was caused by disturbed upper airway reflexes during anesthesia. This process can be analyzed by the distribution of LacZ gene expression in airways. We next examined the effect of age on anesthesia-induced aspiration. Twenty-six-mo-old mice exhibited more LacZ gene expression in their lungs than did 6-mo-old mice at a concentration of 0.5 to 4.0% halothane in 100% oxygen. This suggests that light anesthesia may depress upper airway reflexes and cause aspiration in older animals. This novel model of aspiration, generated with the Ad-CMV-LacZ vector, may be useful for elucidating the mechanism of development of aspiration pneumonia in relation to age-related impairment of upper airway reflexes.

Experimental infection in SPF kittens with a particular calicivirus strain originally isolated from lion

Two SPF kittens were experimentally infected via the intranasal route with a strain of calicivirus originally isolated from sick lion suffering from vesicular disease. Fever, 40.3 degrees C and 40.7 degrees C, and vesicular formation in tongue and snout were reproduced in both kittens. The infected virus was recovered from nasal, oral and rectal swabs. A longer duration of virus recovery was proved with oral swab samples taken from 1 to 10 and 12 days post infection. This suggests that tongue and oral tissues are the main tissues for virus multiplication.

Virological and molecular biological investigations into equine herpes virus type 2 (EHV-2) experimental infections

Two 18-month-old naturally reared ponies were used to investigate the pathogenicity of EHV-2. After dexamethasone treatment, pony 1 was inoculated intranasally with EHV-2 strain T16, which has been isolated from a foal with keratoconjunctivitis superficialis and pony 2 was similarly inoculated with strain LK4 which was originally isolated from a horse with upper respiratory tract disease. Following virus inoculation, pyrexia was not detected in either pony but both developed conjunctivitis, lymphadenopathy, and coughing. EHV-2 was detected in nasal mucus samples up to day 12 post infection (p.i.), in eye swabs up to day 10 p.i., and in buffy coat cells throughout the investigation in both animals. EHV-2-specific antibody titres were raised significantly 18 days p.i. Following the administration of dexamethasone, 3 months p.i., infectious virus was again detected in nasal mucus and conjunctival swabs from both ponies for 7 days. The tissue distribution of EHV-2 genome was studied post mortem, by means of a nested PCR. EHV-2 was detected in lymphoid tissues, lung, conjunctiva, trigeminal ganglia and olfactory lobes of pony 2, whereas in pony 1 only the conjunctiva of the left eye was PCR positive.

Overexpression of interleukin-4 delays virus clearance in mice infected with respiratory syncytial virus

Although interleukin-4 (IL-4) expression has been implicated in vaccine-enhanced respiratory syncytial virus (RSV) disease, its role in mediating the immune response to primary RSV infection remains unclear. To assess the effect of IL-4 production on typical RSV infection, transgenic mice which either overexpress or fail to express IL-4 were challenged intranasally with RSV and their responses were compared to those of the parent strains. IL-4-deficient mice eliminated virus from the lung as quickly as did C57BL/6 controls. In contrast, mice which constitutively overexpress IL-4 showed delayed virus clearance compared with mice of the FVB/N control strain, although peak viral titers did not differ. IL-4 overexpression increased the magnitude of the subsequent antibody response. Lung lymphocytes harvested from IL-4-overexpressing mice post-RSV challenge showed diminished RSV-specific cytolytic activity compared with controls. Both IL-4-deficient and IL-4-overexpressing strains resisted rechallenge. These data imply that constitutive IL-4 expression delays or suppresses the development of a virus-specific cytotoxic lymphocyte population important in clearing primary RSV infection.

Efficacy and safety of the neuraminidase inhibitor zanamivir in the treatment of influenzavirus infections. GG167 Influenza Study Group

BACKGROUND

The sialic acid analogue zanamivir (GG167) is a selective inhibitor of influenza A and B virus neuraminidases. These viral enzymes are essential for the release of virus from infected cells, and they may also reduce the inactivation of virus by respiratory secretions. When administered experimentally directly to the respiratory tract, zanamivir has potent antiviral effects. We assessed the therapeutic activity of zanamivir in adults with acute influenza.

METHODS

We conducted separate randomized, double-blind studies in 38 centers in North America and 32 centers in Europe during the influenza season of 1994-1995. A total of 417 adults with influenza-like illness of < or =48 hours' duration were randomly assigned to one of three treatments: 6.4 mg of zanamivir by intranasal spray plus 10 mg by inhalation, 10 mg of zanamivir by inhalation plus placebo spray, or placebo by both routes. Treatments were self-administered twice daily for five days.

RESULTS

Of 262 patients with confirmed influenza-virus infection (63 percent of all patients), the median length of time to the alleviation of all major symptoms was one day shorter (four days vs. five days) in the 88 patients given inhaled and intranasal zanamivir (P=0.02) and the 85 patients given inhaled zanamivir alone (P=0.05) than in the 89 patients given placebo. Among the infected patients who were febrile at enrollment and among those who began treatment within 30 hours after the onset of symptoms, the median time to the alleviation of major symptoms was four days in both zanamivir groups and seven days in the placebo group (P< or =0.01). Viral titers of nasal washings in the group given inhaled and intranasal zanamivir were significantly lower than those in the placebo group. The topically administered zanamivir was well tolerated.

CONCLUSIONS

In adults with influenza A or B virus infections, direct administration of a selective neuraminidase inhibitor, zanamivir, to the respiratory tract is safe and reduces symptoms if begun early.

A strain of calicivirus isolated from lions with vesicular lesions on tongue and snout

In December 1992, 17 African lions and 7 Siberian tigers in a Safari park in Japan became sick with characteristic clinical symptoms of acute vesicular formations on tongue and snout. The disease was highly contagious since all of these animals showed similar symptoms within two days after the onset of the first case. Swabs were taken from affected animals in rubbing tongues, snouts and some from rectums. Cytopathic viruses were isolated on CRFK cell culture by virological tests. The physicochemical property of a representative virus strain, named Arthur/L, isolated from a male lion was identified as a member of Caliciviridae. However, seroneutralization test indicated that this virus strain was antigenically distinct from Japanese isolates of feline caliciviruses used for comparison. Viral capsid proteins of the present isolate, Arthur/L, and of a feline calicivirus, strain FC7, were compared in an electrophoresis in SDS-PAGE gel. The major viral capsid polypeptide of them were proved to be significantly different in molecular weight. The polypeptide of FC7 was estimated to be ca. 63 KDa whereas that of Arthur/L consisted of 2 components of ca. 65 and 62 KDa. The viral proteins of these two strains were also proved to be distinct by an immunoblotting test.

Evaluation of four methods for the diagnosis of respiratory syncytial virus infection in older adults

OBJECTIVE

To evaluate four methods of rapid diagnosis of respiratory syncytial virus (RSV) infection in older adults and to compare sensitivities with serologic analysis.

DESIGN

Prospective comparative analysis.

SETTING

Two adult daycenters.

PATIENTS

Frail older persons attending the daycenter who developed signs or symptoms of acute respiratory illness between the months of December and February.

MEASUREMENTS

Viral cultures performed by standard technique and bedside inoculation: antigen detection by indirect immunofluorescence assay (IFA) and Directigen enzyme immunoassay (EIA) on nasal brush samples; serologic analysis of acute and convalescent sera using EIA.

RESULTS

RSV infection was documented by serology in 11 of 54 (20%) subjects during the study period. Bedside viral cultures were the most sensitive assay and were positive in 6/9 infections. Standard viral culture detected 5/11 cases. Both methods of rapid antigen detection were found to be insensitive, with 1/11 detected by IFA and 0/11 detected by EIA.

CONCLUSION

Rapid antigen tests for the diagnosis of RSV in older persons should be used with caution.

Comparative severity of respiratory lesions of sialodacryoadenitis virus and Sendai virus infections in LEW and F344 rats

In several chronic diseases, lesions are more severe in LEW rats than in F344 rats. To determine whether or not acute viral diseases also are more severe in LEW rats than in F344 rats, we inoculated 6-7-week-old LEW and F344 rats with 10(7.2) cell culture infective units of sialodacryoadenitis virus or 10(4.7) infective units of Sendai virus. Twenty-four rats of each strain were given each virus. Lesions in nasal passages, tracheas, intrapulmonary airways, and pulmonary alveoli in 6 or 12 rats inoculated with each virus were assessed by scoring 5, 10, and 14 days after inoculation. Both viruses caused typical patchy necrotizing rhinitis, tracheitis, bronchitis, and bronchiolitis, with multifocal pneumonitis, in rats of both strains. Mean lesion indices for LEW rats given sialodacryoadenitis virus were significantly different from those for F344 rats for nasal passages on days 10 (0.999 vs. 0.680) and 14 (0.736 vs. 0.278), bronchi on day 5 (0.479 vs. 0.361), and alveoli on day 5 (0.677 vs. 0.275). Lesion indices for LEW rats given Sendai virus were significantly different from those for F344 rats for nasal passages on days 10 (1.000 vs. 0.611) and 14 (0.778 vs. 0.583); trachea on day 10 (0.625 vs. 0.028); bronchi on days 5 (0.476 vs. 0.331), 10 (0.123 vs. 0.013), and 14 (0.038 vs. 0); and alveoli on days 5 (0.413 vs. 0.114) and 10 (0.185 vs. 0.020). Thus, at the tested doses, both viruses caused more severe respiratory tract lesions in LEW rats than in F344 rats.

Systemic immunoprophylaxis of nasal respiratory syncytial virus infection in cotton rats

The cotton rat model was used to test whether systemically administered immunoglobulin could protect nasal tissues against low challenge doses of respiratory syncytial virus (RSV). Animals were pretreated by intraperitoneal injection of human immunoglobulin with moderate (1:2226) or high (1:15,000) neutralizing antibody titers to RSV (day 0), challenged intranasally with RSV Long at doses ranging from 10(1) to 10(5) pfu (day 1), and sacrificed for virus titration (day 5). Pretreatment with moderate-titer immunoglobulin effected complete or near complete nasal protection against low to moderate (10(1)-10(3) pfu) RSV challenge doses and a significant reduction in nasal RSV titers at high (10(4)-10(5) pfu) challenge doses. Pretreatment with high-titer immunoglobulin effected near complete nasal protection at an RSV challenge dose of 10(3) pfu and highly significant and significant reductions in nasal RSV titers at challenge doses of 10(4) and 10(5) pfu, respectively. Immunoprophylaxis effected complete or near complete pulmonary protection at all RSV challenge doses.

[Biology of bovine pestivirus infection responsible for mucosal disease]

The virus BVD/MD belongs to the genus pestivirus from the family Flaviviridae, as well as viruses responsible for hog cholera and border disease. BVD/MD virus is responsible for two distinct disease entities in cattle: bovine virus diarrhoea (BVD), which is characterized by high morbidity and low mortality, and mucosal disease (MD) which is sporadic but highly fatal. BFV/MD virus exists under two biotypes among which antigenic pairs: a non cytopathic and a cytopathic biotypes. These biological characters are purely cultural and do not correspond to the in vivo pathogenic behaviour. Recent experiments from our group show that the two biotypes of a same antigenic pair differ by their biological properties in the target animal. The cytopathic strain, contrary to the non cytopathic one, induces belated both humoral and cellular immune responses. Only non-cytopathic strain produces viraemia and nasal excretion. These results confirm the fact that non-cytopathic strains represent an epidemiological dead end. These results also permit to envisage a logical modelisation of the infection at a population level.