Role Of Respiratory Syncytial Virus Research Articles

The Role of Respiratory Syncytial Virus (RSV) in the Etiology of Atopy and Asthma

The Role of Respiratory Syncytial Virus (RSV) in the Etiology of Atopy and Asthma

Effect of respiratory syncytial virus on subsequent allergic sensitization to ovalbumin in guinea-pigs.

Children with acute respiratory syncytial virus (RSV) bronchiolitis often develop recurrent wheezing, asthma and allergic sensitization, but the role of RSV in the pathogenesis of these sequelae is unclear. This study examined whether RSV infection potentiates subsequent allergic sensitization, airway hyperresponsiveness (AHR) and airway inflammation induced by repeated exposures to aerosolized ovalbumin (OA) in guinea-pigs. Guinea-pigs received either RSV or sham inoculum, followed by exposures to OA- or saline-containing aerosols to form the following groups: 1) noninfected, nonsensitized controls (sham/saline group); 2) RSV-infected, nonsensitized animals (RSV/ saline group); 3) noninfected, OA-sensitized animals (sham/OA group); 4) RSV infection and first OA exposure on the same day (RSV/OA group), and 5) RSV infection six days prior to first OA exposure (RSV6/OA group). Three days after the final aerosol exposure, circulating OA-specific immunoglobulin (Ig)G1 antibody titres and AHR to inhalation acetylcholine challenge were measured and morphometry performed to evaluate allergic inflammation of the airways. OA-exposed animals developed OA-specific IgG1 antibodies, AHR and airway eosinophilia (sham/OA, RSV/OA and RSV6/OA groups. RSV infection alone induced significant AHR and airway eosinophilia (RSV/saline group). RSV infection, and concomitant exposure to OA (RSV/OA group) enhanced OA-specific IgG1 antibodies, but not airway eosinophilia or AHR. Such increases were not observed in the RSV6/OA group. In conclusion, respiratory syncytial virus potentiates the production of ovalbumin-specific immunoglobulin G1 antibodies in guinea-pigs, but circulating titres of these antibodies do not reflect the extent of airway hyperresponsiveness or airway inflammation. In addition, respiratory syncytial virus infection alone can produce slight increases in airway hyperresponsiveness that are associated with increased numbers of eosinophils in the airways.

Respiratory syncytial virus infections in children in a desert country.

The role of respiratory syncytial virus (RSV) in acute lower respiratory infection in infants and young children in Kuwait was investigated in a prospective study. Of the 523 children under 13 years of age admitted to Mubarak Al-Kabeer Hospital between August 1993 and June 1994 209 (40%) had RSV infection. 170 (81%) of these children had no underlying symptoms 25 (12%) had asthma 6 (3%) had neurologic diseases 3 (1.4%) had congenital heart disease and 2 (1%) were preterm. The median age of RSV-positive children was 7.2 months. 89% of RSV cases occurred during the winter months. Acute bronchiolitis was the most frequent clinical feature followed by pneumonia and croup. The median duration of hospitalization was 6 days. In most cases treatment was supportive (e.g. oxygen administration in 90% and intravenous fluids in 65%); 30% of children received antibiotics. There were 3 deaths in this series for a case fatality rate of 1.4%. The 3 children who died had underlying conditions and were not treated with ribavirin.

幼若乳児の気道感染症とRespiratory Syncytial Virus

We investigated the role of respiratory syncytial virus (RSV) in respiratory tract infections of up-to-3-months old infants. This prospective study was carried out from April 1993 to March 1994. Detection of RSV antigen in nasopharyngeal specimens was done by enzyme immunoassay using TESTPACK RSV at our out patient clinic. During this study period, 65 young infants with respiratory tract infection visited our clinic. Seventeen patients (26%) were diagnosed as having RSV infection. Fifteen out of the 17 infants with RSV infection were observed in spring and winter. Fourteen out of the 17 infants with RSV infection had acute bronchiolitis or pneumonia. In contrast to RSV infection, only three patients out of the 48 infants with non-RSV infection had lower respiratory tract infection. In conclusion, the majority of young infants infected with RSV suffered from bronchiolitis or pneumonia.

The role of respiratory syncytial virus in acute bronchiolitis in small children in northern Japan.

Respiratory syncytial virus (RSV) plays an important role in acute bronchiolitis, which is life threatening in some infants. We investigated the epidemiology of RSV acute bronchiolitis in children less than 3 years old in northern Japan. From April 1991 to March 1993, 162 infants with acute bronchiolitis were hospitalized in our pediatric wards. The diagnosis of RSV acute bronchiolitis was based on the typical clinical manifestations and the presence of RSV antigen in their nasopharyngeal specimens or the rise of the RSV antibody titer. 124 out of 162 patients (76.5%) were diagnosed as having RSV acute bronchiolitis. 43.5% of patients with RSV acute bronchiolitis were 6 months old or less. The epidemic of RSV acute bronchiolitis commenced in October, peaked in December and ended in summer. RSV is quite prevalent in infants with acute bronchiolitis in northern Japan.

Production of acute bronchiolitis in guinea-pigs by human respiratory syncytial virus

Respiratory syncytial virus (RSV) is the most important cause of acute bronchiolitis in young children, and is implicated in the pathogenesis of paediatric asthma. The present studies were designed to develop a model of acute RSV bronchiolitis in young guinea-pigs, that could be used to study the mechanisms of the acute bronchiolitis and its sequelae. Anaesthetized, one month old guinea-pigs received either 4 x 10(3) plaque forming units of Long strain human RSV or uninfected cell culture medium intranasally. Bronchiolar inflammation was assessed 6 days (n = 10 RSV-inoculated; n = 10 controls) and 14 days (n = 10 RSV-inoculated; n = 9 controls) postinoculation using a semiquantitative histological scoring system. Viral replication within the lung was evaluated by culture, and the intrapulmonary distribution of viral antigens was evaluated by immunohistochemistry. The RSV-inoculated group showed histological evidence of acute bronchiolitis 6 days after inoculation, which subsided by Day 14. Replicating virus was cultured from the lungs of 9 out of 10 RSV-inoculated animals on Day 6, and 2 out of 10 animals on Day 14, with no growth from control animals. Viral antigens were identified primarily within airway epithelial cells on Day 6, and within alveolar macrophages on Day 14. Intranasal inoculation of human RSV into guinea-pigs provides a model of acute RSV bronchiolitis that may facilitate the study of both the pathogenesis of acute infection and the possible role of RSV in the subsequent development of nonspecific bronchial hyperresponsiveness in children.

小児しん出性中耳炎へのＲＳウイルスの関与 ＲＳウイルスゲノムの貯留液での検出

The role of respiratory syncytial virus (RS virus) in otitis media with effusion was studied. Reverse transcriptase-polymerase chain reaction (RT-PCR) and nested polymerase chain reaction (Nested PCR) were used to provide accurate methods for detection of RS viral sequences in the otitis media effusion from children. We could find RS viral sequences in 10/12 samples tested which had been collected during and even after natural outbreak of RSV in the community. These observations suggest RS virus as an important factor in the pathogenesis of otitis media with effusion. The disturbance of the local humoral and cell-mediated immune response in the middle ear accompanied with RS virus infection may lead to the development of infection-induced inflammation and ventilatory compromise, development of suppurative and effusion, multiplication of low virulence pathogens and subsequent development of mucosal damage.

432 Role of respiratory syncytial virus (RSV)-induced eosinophil degranulation in bronchiolitis

432 Role of respiratory syncytial virus (RSV)-induced eosinophil degranulation in bronchiolitis

Role of respiratory syncytial virus in early hospitalizations for respiratory distress of young infants with cystic fibrosis

To determine the frequency of respiratory syncytial virus (RSV) as the cause of hospitalization for acute pulmonary exacerbations in young infants with cystic fibrosis (CF), and to assess the clinical effects of RSV infections, we prospectively followed 48 children with a diagnosis of CF after identification by newborn screening. At a mean follow-up age of 28.8 months (range 5 to 59), 18 infants (38%) had been hospitalized a total of 30 times for acute respiratory distress. At the time of admission, 18 infants (60%) were less than 12 months, 8 (27%) between 12 and 24 months, and 4 more than 2 years of age. The RSV was identified in seven hospitalized infants, as determined by fluorescent antibody, immunoassay, or culture. Before admission with RSV infection, one of the seven infants had chronic respiratory signs, none had Brasfield chest x-ray scores below 20, and a previous throat culture was positive for Staphylococcus aureus in one infant. Hospitalizations were prolonged (mean duration 22 days), and were characterized by significant morbidity, with three infants (43%) requiring mechanical ventilation and five infants (71%) requiring home oxygen therapy for persistent hypoxemia at discharge. At a mean follow-up age of 26 months, these infants more frequently have chronic respiratory signs (p less than 0.01) and lower chest radiograph scores (p less than 0.05) than other CF infants. These findings demonstrate that RSV is an important cause of early acute respiratory tract morbidity in young infants with CF, and suggest the need for studying new strategies to implement early and aggressive antiviral therapy in young infants with CF.

A study of respiratory infections in the elderly to assess the role of respiratory syncytial virus.

A prospective study was performed from 1 December 1981 to 31 May 1982 in two departments of geriatric medicine in Edinburgh. This yielded 159 cases of acute respiratory tract infection (RTI). Twelve of these were undoubtedly associated with respiratory syncytial virus (RSV), 14 with influenza A and 18 with influenza B (as established in each case by a fourfold or greater increase in antibody titre). Eighty-five of the 159 patients with RTI and RSV titres of 32 or greater. Their significance is discussed. The undoubted RSV infections all involved the lower respiratory tract and were associated with prolonged illness. This epidemic of RSV infection was confined to one of the two hospitals. It lasted less than four weeks and was probably hospital-acquired.

The role of respiratory syncytial virus and other viral pathogens in acute otitis media

We utilized recently developed enzyme immunoassay techniques to examine the role of selected viruses in the etiology of acute otitis media. Viral pathogens were found in middle ear fluids obtained from 13 (24%) of 53 children with acute otitis media; respiratory syncytial virus accounted for ten of the 13 viral agents identified. In addition, respiratory syncytial viral antigen was found in nasopharyngeal washings obtained from 15 of the 53 children. Seven of these children had RSV identified as the sole middle ear pathogen, whereas six children had otitis caused by Streptococcus pneumoniae as either the sole middle ear pathogen or in combination with RSV. Similarly, all three children with respiratory infections caused by influenza virus had ear infections caused by bacterial pathogens, either alone or in combination with influenza virus. These findings suggest that, in patients with viral respiratory infection, coexisting acute otitis media may be associated with the recovery of either viruses or bacteria from the middle ear exudates.

Respiratory syncytial virus infection: ten-year follow-up.

Studies within the last 20 years have shown that the incidence of asthma is increased in children who have been hospitalized with bronchiolitis due to respiratory syncytial virus. To evaluate such respiratory consequences in an ambulatory population, a follow-up study was done of 37 children who had respiratory syncytial virus infection documented at a community pediatric clinic in 1968 when they were younger than 4 years. This study, done ten years later by chart review and parental interview, showed that asthma had subsequently been diagnosed in three (8%). Thus, an increased risk for the development of asthma after respiratory syncytial virus infection was not found. Comparison of these data with those from previous reviews questions a causative role for respiratory syncytial virus in childhood asthma.

The possible role of respiratory syncytial virus and Pasteurella spp in calf respiratory disease.

In a natural outbreak of respiratory disease during 1976, 31 of 43 calves showed moderately severe clinical signs which included pyrexia (maximum 42 degrees C) and tachypnoea. During the outbreak infection by respiratory syncytial virus (RSV) was demonstrated by isolation from nasopharyngeal swabs or by serology. Pasteurella haemolytica or P multocida were isolated from the blood of four and five calves respectively. In the month before disease 65 per cent of the calves showed significant antibody responses to P haemolytica. However a similar serological response to P haemolytica was demonstrated during 1975 in a comparable group of calves in which no disease and no infection with RSV was detected. No serological response to P multocida was demonstrated in either year. The temporal correlation of RSV infection with respiratory disease in the group of 43 calves was striking but the evidence neither reinforced nor discounted the possibility of interaction between RSV and P haemolytica infection in the pathogenesis of disease.

The role of respiratory syncytial virus in otitis media in children.

Thirty-three children with acute respiratory infection and intratympanic mucus or fluid accumulation were studied during a respiratory syncytial (RS) virus outbreak. Throat swabs and middle ear aspirates were cultured for virus using a direct inoculation technique. RS virus was recovered from the throat swabs of 18, from one or both ears of 7 of these virus-positive subjects, and with about equal frequency from ears showing signs of slight inflammation and ears with injected, reddened and/ or bulging eardrums. It was recovered from two aspirates obtained at subsequent punctures from the same ear, from aspirates also yielding a bacterial pathogen, and from the aspirate of a subject no younger than 3 years old. None of the children with virus-neagtive throat swabs showed virus in their aspirates. “Within this group there was a strikingly high number of subjects displaying evidence of recent RS virus infection (CF antibodies to a high titer in the acute serum). The origin of the mucus, the clinical significa...