Respiratory syncytial virus-induced chronic bronchiolitis in experimentally infected calves

Abstract

Human (RSV) and bovine (BRSV) respiratory syncytial virus cause similar infections of the lower respiratory tract. Therefore, experimentally infected calves are suited to the study of RSV-induced chronic bronchiolitis. Colostrum-fed calves aged 17-24 days were successfully infected with BRSV. BRSV strain 375 was applied as an aerosol on 4 consecutive days. Clinical symptoms were already evident on the 1st day after infection. The calves were necropsied 12 weeks after the first infection. Focal severe chronic bronchiolitis with atelectasis and focal bronchiolitis obliterans were demonstrated. The bronchiolar lumina were filled with secretion. Transmission electron microscopy revealed an alteration of the ciliogenesis and partial loss of cilia. Immunhistochemically virus P protein could still be detected, mainly in the epithelial cells of the inflamed bronchioli.

The histopathology of fatal untreated human respiratory syncytial virus infection

“…This is consistent with the distribution of virus-infected cells in reports of the pathology of bovine RSV in calves, 11 and indicates that lower respiratory disease from RSV infection is not just an indirect effect of infection in the bronchiolar epithelium, but reflects direct virus infection of the alveolar epithelium. The finding of extensive virus infection in both the small airways and the alveolar epithelium in patient 3 who was recently diagnosed and being managed as an outpatient is particularly enlightening.…”

Animal Pneumoviruses: Molecular Genetics and Pathogenesis

“…In the study performed by Philippou et al (287), lungs from animals sacrificed at 12 weeks postinoculation were atelectatic with evidence of bronchiolar obstruction and profound inflammatory infiltration. Disease progression has been associated with increased expression of IL-2, IL-4, and/or gamma interferon in cells drained from pulmonary lymph (139,214) and in peripheral blood mononuclear cells (257), detection of tumor necrosis factor alpha and leukotriene B4 in respiratory secretions (302,308), and elevations in levels of serum acute-phase response proteins (171).…”

“…Experimental models of bRSV infection in calves involve aerosol administration of virions, resulting in early-onset cough and nasal discharge and progressing to signs and symptoms of lower respiratory tract infection (287,350,367,380). In the study performed by Philippou et al (287), lungs from animals sacrificed at 12 weeks postinoculation were atelectatic with evidence of bronchiolar obstruction and profound inflammatory infiltration.…”

Intranasal Immunization of Mice with a Bovine Respiratory Syncytial Virus Vaccine Induces Superior Immunity and Protection Compared to Those by Subcutaneous Delivery or Combinations of Intranasal and Subcutaneous Prime-Boost Strategies

“…It has been estimated that BRSV is responsible for more than 60% of epizootic respiratory disease in dairy herds and up to 70% in beef herds, with typical mortality levels ranging from 2 to 3% but reaching 20% in some cases (38). HRSV and BRSV have similar clinical outcomes in their respective host species, ranging from asymptomatic infection to bronchiolitis and pneumonia, and sometimes death (46), and the pathogeneses of both viruses are directly related to the host immune response (19).…”