An electron microscopic study of feline lymphosarcoma

Laird, Helen M (1968) An electron microscopic study of feline lymphosarcoma. PhD thesis, University of Glasgow.

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Lymphosarcoma, leukaemia or malignant lymphoma is a well recognised disease of the cat; its true incidence is not known. The aetiology of the disease has not been established hue some experiments have suggested that a virus is involved. This study is concerned with electron micros-copic examinations of material from field eases of feline lymphosarcoma and from animals and tissue cultures infected with feline leukemic tissue extracts. In Section 1 the examination of tissues from 9 randomly collected cats with spontaneous lymphosarcoma is described. particles: morphologically similar to the murine leukamia viruses, were found to be present in of these cats. The particles, approximately 100mum in diameter were of 2 types. The structure of Typo 1 particles consisted of the outer hounding membrane within which there was an electron-dense membrane with a diameter of approximately 50 60mum and an intermediate membrane with a diameter of approximately 80mum. The structure of Type 2 particles consisted of the outer bounding membrane within which there was an electron-denae nuoieoid with a diameter of approximately 60 mum. Some particles appeared to have a "coating layer" on the outer surface of the bounding membrane. The particles were found in one or more of the following tissues, spleen, bone marrow, thymus, periphera lymph nodes, and were found associated with lymphoid cells and megakaryocytes. Fully-formed particles were seen extracellularly and in intracellular vacuoles; budding particles were observed at plasma membrane and vacuolar membranes and the various stages of particle replication at these surfaces were seen. In material from each of the other 3 eases of Spontaneous lympbosarcoma a few virus-like particles were noted. No correlation was established between the classification of a case according to the anatomical distribution of the lesions or the histopachological findings and the presence or absence of large numbers of particles. No particles were seen in tissues from a series of normal cats. In Section 2 are described experiments with leukaemia tissue extracts from 3 of the particle-positive cases described in Section 1 and from 1 of the cases in which only a few virus-like particles were observed. Newborn kittens were infected with these inocula. Blood samples were taken from the kittens at various time, from 28 days to 1 year after inoculation, and tissue samples taken from kittens killed or dying at various times during the same period. It was found that particles could be demonstrated in the blood platelets and tissues, The inocula derived from the field ease classified as moat particle-positive induced particle replication in all of the kittens infected and both fully formed and budding particles were seen. Lymphosarcoma was histologically con-firmed in some of the inoculated kittens. The second inoculum induced replication in some kittens but fewer particles Were found associated with the platelets and fewer tissues were found to contain particles, The third inoculum induced replication to a lesser extent. No particles were found in the kittens infected with the inoculum derived from the particle-negative case. Normal kittens and kittens infected with a normal lymph node extract were examined; in one kitten from each group a few virus-like structures were observed. Section 3 describes further transmission experiments. It was found that: a filtrate inoculum induced in kittens particle replication similar to that induced by the presumed cell-free extracts. It was also shown that particle replication could be induced in adult cats which had been inoculated with a leukaemic tissue extract. Further, it was demonstrated that an inoculum from an infected kitten with no evidence of lymphosarcoma but with particles present in platelets could induce particle replication in kittens; this method of passage was successfully carried out through 4 passage generations. Section 4 deals with the growth of the particles in tissue cultures. Two feline cell cultures were examined and inocula derived from 3 of the particle-positive field cases were tested in these Cultures. It was shown that particle replication could take place in both types of cultures and that 2 of the 3 inocula investigated were effective in this respect. The 2 inocula which induced replication in tissue cultures were those which had been shown to be most active in inducing replication in newborn kittens and which had been derived from the field cases classified as the most particle-positive. Section 5 describes attempts to isolate particles from leukaemic tissues from a field ease, from plasma from inoculated kittens and from tissue culture fluid from cultures infected with leukaemia tissue entreats. Most preparations contained no particles; a few virus-like structures were seen in some tissue extracts and in a subsequent study, particles were found in tissue culture fluid. Attempts to induce leukaemia in rats and mice, using feline leukaemic tissue extracts are described in Section 6. No evidence of particle replication could be detected in blood platelets or tissue and in a 10 month period of observation, no animal developed leukaemia.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: William Weipers
Keywords: Veterinary science
Date of Award: 1968
Depositing User: Enlighten Team
Unique ID: glathesis:1968-72117
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 17 May 2019 12:55
Last Modified: 17 May 2019 12:55

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