Respiratory syncytial virus and parainfluenza type 3 virus infections in cattle

Watt, Neil J (1983) Respiratory syncytial virus and parainfluenza type 3 virus infections in cattle. PhD thesis, University of Glasgow.

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Respiratory diseases are economically important in the U.K. Those which affect young, immature, housed calves have been difficult to define in aetiological terms despite many years of research. Many viruses, bacteria and mycoplasmas have been associated with these diseases but in recent years the pathogenic roles of respiratory syncytial virus and parainfluenza type 3 virus have demanded particular attention. The aim of this thesis was to investigate the part played by these two viruses in the respiratory diseases of cattle with particular reference to the pathogenesis, diagnosis and differential diagnosis of these two infections in naturally occurring outbreaks of disease. These primary aims were to be accompanied by attempts to produce viral infection in experimental calves using isolates of the viruses obtained during the field investigations. A multidisciplinary investigation into 22 outbreaks of acute respiratory disease in immature cattle was carried out using clinical, microbiological and pathological techniques. Eight outbreaks were detected in which there was unequivocal evidence of infection with either RS virus or PIS virus. In addition 16 individual cases of RS viral infection and one case of PIS viral infection v/ere detected in material referred from Veterinary Investigation Centres in England. Common clinical findings in RS viral cases were hyperpnoea, tachypnoea and, in severe cases, dyspnoea. On pathological examination there v/as pneumonia involving the cranial parts of the lung lobes and, in fatal cases, severe interstitial emphysema with the formation of gas-filled bullae in the caudal lobes. Microscopically syncytium formation in the epithelia of the bronchioles, the alveoli and, very occasionally, the bronchi was found. Virus-infected cells sometimes contained eosinophilic intracytoplasmic inclusion bodies. Three new strains of RS virus were recovered during these investigations. Relatively few individual cases of PIS viral infection were discovered, however, in these there was also inclusion body formation in the cytoplasm of respiratory epithelial cells and, occasionally, epithelial syncytia were present. Secondary bacterial infection was common with Pasteurella multocida and Pasteurella haemolytica types A1 and A2 involved, Due to the similar nature of the specific pathological changes due to RS viral and PIS viral infections it was found necessary to develop a technique which could distinguish between these two infections in the lung. Immunofluorescent staining of viral antigens in either acetone-fixed or formalin-fixed sections of pneumonic lung was developed for this. The detection of antigens in lung which was been fixed for conventional histopathology was a significant advance on previous techniques as it enabled the relationship between the viral antigens and the histopathological changes to be assessed more fully. Experimental infections were carried out using RS virus and PIS virus. Unfortunately it was not possible to use the isolates of RS virus which had been recovered during the field investigations. Using an RS virus isolate obtained from a another laboratory calves were successfully infected. Combined infection with the cattle lungworm Dictyocaulus viviparus was attempted in order to potentiate the effects of the viral infection. Although viral infection was established there was no unequivocal evidence that this was increased in severity by concomitant D.viviparus Infection. Two groups of calves, one aged two weeks and the other four months, were infected with a recent field isolate of PIS virus. In both groups viral infection was associated with clinical signs of respiratory disease and pathological lesions, specifically recognisable as being due to PIS viral infection, were produced in the lower respiratory tract.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: H M Pirie
Keywords: Animal diseases
Date of Award: 1983
Depositing User: Enlighten Team
Unique ID: glathesis:1983-72334
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 24 May 2019 15:12
Last Modified: 24 May 2019 15:12

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