Anaplasma marginale-infectivity in splenectomized and radiated rabbits : a dissertation /
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
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[College Station, Tex.] :
[Texas A&M University],
[1968]
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| Abstract: | ABSTRACT: The purpose of this study was to determine if an A. marginale infection was possible in rabbits and if any changes in the etiologic agent could be detected. To alter their receptivity intact and splenectomized rabbits were subjected to different amounts of Co⁶⁰ gamma radiation. The inoculum consisted of anaplasma infected bovine whole blood, freshly drawn, containing intact erythrocytes. There was no A. marginale development detectable by laboratory means neither in intact radiated rabbits, nor in splenectomized, nor in splenectomized and radiated rabbits. A single intravenous injection of virulent A. marginale in these rabbits did not elicit a detectable CF antibody response. These results excluded that an antigenic response had taken place even as a result of an inapparent A. marginale multiplication in the rabbits. There was no A. marginale infectivity, biologically demonstrable, in the blood of splenectomized and radiated rabbits neither after 10, 20, 40 nor 60 days. When this rabbit blood was injected into splenectomized susceptible calves it did not reproduce the disease. None of the calves inoculated with rabbit blood showed a detectable CF antibodies response. When these calves were challenged with anaplasma carrier blood all died of acute anaplasmosis. This excluded the hypothesis that rabbits were "asymptomatic carriers." This also proved that the blood of anaplasma injected rabbits was neither pathogenic, antigenic nor had any premunizing properties for susceptible calves within the 60 days period tested. If there were an A. marginale infection taking place in the rabbits, after a period of adaptation and multiplication of the etiologic agent, the incubation period should have been beyond the 60 days tested. The survival of A. marginale injected into rabbits was biologically detected by time lapse sub-inoculations into splenectomized calves. The calves sub-inoculated within 24 hours had a shorter incubation period than those sub-inoculated at 48 hours. This was probably due to a numerical progressive reduction of the etiologic agent. All calves inoculated within 48 hours had an acute lethal anaplasmosis. These results led to the conclusion that within this period A. marginale did not undergo any detectable change in virulence while exposed in vivo to the rabbit tissue enzymes. However calves sub-inoculated at 120, 240 and 480 hours remained negative and when challenged proved to be fully susceptible. It was concluded that rabbits neither allowed a detectable multiplicaion of the A. marginale organism in their blood nor underwent a "negative phase" nor that they were "asymptomatic carriers" of the disease. A. marginale survived in rabbits without a detectable change in virulence for mroe than 48 hours and less than 120 hours. |
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| Item Description: | Vita. "Major Subject: Veterinary Microbiology". "Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements for the degree of Doctor of Philosophy January 1968." |
| Physical Description: | ix, 66 leaves : tables ; 28 cm |
| Bibliography: | Includes bibliographical references. |