Immunological responses of Gallus domesticus to infection with Trypanosoma brucei

Joshua, Richard Adekunle (1979) Immunological responses of Gallus domesticus to infection with Trypanosoma brucei. PhD thesis, University of Glasgow.

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Birds have long Been reported to be among the possible hosts of T. brucei (Durham, 1908); however, the use of birds for the elucidation of the immune response to trypanosome infection has had relatively little investigation. This thesis has examined the nature of T. brucei brucei infections in birds as well as the significance of the parasite in the development of the very numerous germinal centres which appear in the spleen during the course of a chronic infection. Three lines of salivarian trypanosomes were tested for infectivity to birds; only organisms derived from the primary isolation Lugala/55/EATRO/-459 were found to produce an infection. This persisted for over one year. A comparison of current diagnostic methods showed that mouse inoculation, DEAE column chromatography and development in the serum of heterophile agglutinins (against rabbit, guinea-pig and rat erythrocytes) were of value for detection of infection in chickens. Parasitaemia was maintained at a low level (<105.4 per ml, of blood) in all of the infected birds; infectivity titration of chicken blood in mice revealed the presence of 3-100 viable organisms per ml, of blood. Quantitative estimation of toe number of organisms required to infect chickens showed that trypanosomiasis can follow the inoculation inoculation of one hundred mouse infective doses (ID63); the intravenous route was the most efficient route for initiating infection. Advances and remissions of parasitaemia were detected during the course of the infection in chickens and seven variable antigen types were isolated, thus suggesting that, as in mammals, T. brucei undergoes antigenic variation during a chronic infection. Starting with a well authenticated stock of T. brucei brucei and after a long passage in chickens a clone of trypanosomes which was resistant to normal human serum and therefore of potential infectivity for man was isolated. This observation implies that T.b. brucei which was devoid of pathogenicity for man could transform by passage in the bird to acquire the ability to infect man. The infection persisted much longer in cockerels than in pullets. Chronic trypanosomiasis produced no obvious impairment of health in the birds; their growth rate was indistinguishable from normal, but neonatally infected pullets laid fewer eggs than controls. Histological examination showed an increase of over ten fold in the number of germinal centres in the spleen. Hypotheses are discussed which might account for this increase. It is argued that the development of such a large large number of germinal centres reflects the bird's response to the elaboration of a succession of trypanosome antigens. Injection of an unrelated antigen (Human serum albumin) into infected birds led to the formation of a limited number of germinal centres each containing H.S.A. bearing dendritic cells. The results of these experiments imply that germinal centres of trypanosome infected birds were specific for trypanosome antigen and attempts were made to demonstrate this by the fluorescent antibody technique. The kinetics of formation of germinal centres during trypanosome infection and the kinetics of their decrease after treatment with a trypanocide were explored. It was observed that chickens which spontaneously cured themselves of their infection with trypanosomes showed immunity against challenge with variants from the same stock. This demonstration of specifically acquired immunity implies that the use of trypanosome vaccines could lead to the successful induction of immunity.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: R G White
Keywords: Animal diseases, Parasitology
Date of Award: 1979
Depositing User: Enlighten Team
Unique ID: glathesis:1979-73811
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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