Herpes virus infection of pigeons

Cornwell, Harold J.C (1968) Herpes virus infection of pigeons. PhD thesis, University of Glasgow.

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The thesis reports the isolation of a herpesvirus from two outbreaks of disease among racing pigeons in the West of Scotland. In both outbreaks the infection seemed to be enzootic and was probably maintained by healthy adult carriers. Thus, although each flock was self-contained, the disease recurred annually in both lofts over several years and only involved birds of five to six weeks of age. Clinical signs included serious conjunctivitis and rhinitis, weakness and general malaise. Some birds were dyspnoeic, probably due to the presence of small diphtheritic patches on the mucous membrane of the larynx. The most constant post-mortem finding was focal hepatic necrosis, but renal necrosis was also noted in some birds. Basophilic or slightly eosinophilic intranuclear inclusions were found in parenchymal cells adjacent to the necrotic foci and were also noted occasionally in epithelial cells adjacent to exudate-coated ulcers in the pharynx and larynx. Examinations for the ornithosis agent proved negative, but small whitish-cream pocks were produced on the chorio-allantoic membranes of ten-day embryonated hens' eggs inoculated with tissue suspensions from six birds and with a throat swab from a seventh. Embryos became sluggish and often died about the fifth day. The pocks produced by all isolates generally attained a maximum diameter of 1 mm. on the fourth day, but dendritic extensions were sometimes present. Intranuclear inclusions, typical of those produced by herpesviruses, were prominent in ectodermal cells on the second day, but diminished in number thereafter and, by the fifth day, were almost entirely absent. Foci of necrosis in the embryonic liver could often be appreciated macroscopically by the fourth day. Intranuclear inclusions were present in hepatic cells adjacent to those food. Hepatic necrosis was a regular finding in embryos inoculated by the yolk-sac route and also sometimes occurred in embryos infected amniotically, but the virus could not be propagated by allantoic inoculation. All isolates were cytopathogenic in whole chick-embryo cultures, the cytopathogenic effect (C.P.C.) being characterized by the appearances of foci of round, refractive cells, some of which were considerably swollen. With concentrated inocula, the C.P.E. appeared within 24 hours and the monolayer was completely destroyed by the fourth or fifth day with release of virus into the culture-fluids. The agent was cytopathogenic in cultures of chick-embryo kidney, chick-embryo liver, chicken kidney and pigeon kidney but did not multiply in HeLa cells, in Strain L cells on in primary cultures of dog or calf kidney. The C.P.E. was essentially the same in all avain cultures employed. In contrast to the above findings, a strain of infectious laryngo-tracheitis (I.L.T.) virus was found to produce small syncytia in the epithelial component of whole-embryo cultures but no C.P.E. in fibroblasts. Intermediate in its effects was the P-5 strain of pigoon I.N.I. virus isolated by Smadel et al. in 1945. This strain, kindly supplied to the writer, produced small syncytia in the epithelial component of whole-embryo cultures and rounding of the fibroblasts. All isolates produced plaques in whole-embryo cultures maintained under an agar overlay. These appeared on the second or third day and by the fourth day; varied in diameter from 0.5 mm. to 2 mm. though the largest did not increase in size thereafter. Although "small-plaque" variants were found to be present, much of the variations in plaque-diameter was shown to be non-genetic in character. A linear relationship was found to exist between plaque-count and virus input and evidence was obtained to indicate that the distribution of plaques follows the Poisson equation. Replicate assays of stock virus gave approximately the same titre in cultures of different batches. The ratio of plaque-forming to pock-forming was found to be around 1.5 to 1. Plaques were also formed under methylcellulose, the relationship between plaque-count and relative virus concentration again being linear. The plating-efficiency under methylcellulose was approximately double that under agar. About 50 percent of the virus attached to monolayers of whole-embryo cells in 95 minutes but absorption was not complete before the end of the sixth hour. The DNA nature of the virus was demonstrated by inhibition with bromo- and iodo-deoxyuridines. By means of the negative staining techniques of electron microscopy, the virion was shown to be typical of that of the herpesvirus group. The virus was other-sensitive and was destroyed by exposure to a pH of 4.0. It was quickly destroyed at 56

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: J W Emslie
Keywords: Veterinary science, Animal diseases
Date of Award: 1968
Depositing User: Enlighten Team
Unique ID: glathesis:1968-72012
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 17 May 2019 13:25
Last Modified: 17 May 2019 13:25
URI: http://theses.gla.ac.uk/id/eprint/72012

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