| Mechanisms of resistance in Pasteurella tularensis infections. | |
Abstract/OtherAbstract
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Host mechanisms of resistance in infectious diseases are not completely understood at the present time. In an effort to gain insight into the relationships between humoral and cellular factors in natural and acquired resistance to Pasteurella tularensis infections, several different aspects of the host-parasite relationships were investigated. These studies were made in rabbits, mice and guinea pigs using four strains of the organism with virulence variations ranging from avirulent to fully virulent (LD100 = one organism) for the three animal species. The studies included: 1) Susceptibilities of normal and immunized animals to the strains of the organism; 2) determination of susceptibility after x-irradiation; 3) in vitro phagocytosis using a standard bacteriological plate count and a radioisotope labeling method; 4) in vivo phagocytosis by the reticuloendothelial system; 5) bactericidal activities in vitro of normal and immune sera; 6) passive transfer of phagocytic cells; 7) passive transfer of serum; and 8) effects of age in acquired immunity. Animals were found to be able to withstand an organism challenge of all strains ranging from 10(4) to 10(5) times that of normal animals after being immunized with strains of lesser virulence. Immunized animals when infected with virulent strains reacted as though the strains were of attenuated virulence. It was found that specific immunization protected x-irradiated animals against P. tularensis challenge. The degree of resistance elicited could be related to the viability of the phagocytes of the irradiated animals as determined by challenging the animals at various times pre- and post-irradiation. Phagocytic studies conducted in vitro, using both methods listed above, indicated that immune macrophages from mouse, guinea pig and rabbit peritoneal cavities, and macrophages from the lungs of the latter two Species had markedly increased intracellular destructive capacities for all strains of the bacterium as compared to cells from normal animals. Increased ingestive rates for the immune cells were also noted in these studies. Extracellular specific antibodies were not found to affect phagocytosis in any of the cells. Autologous, homologous and heterologous sera had little, if any effects on phagocytosis, either the ingestive or the digestive phase. Streptomycin did not affect intracellular organisms. The phagocytes of the reticuloendothelial systems of mice and rabbits were found to have measurably enhanced destructive capacities for the ingested bacteria after immunization. Further, passive cellular transfer using homologous and heterologous immune macrophages, both alveolar and peritoneal, protected all three animal species against challenge with all strains of P. tularensis. In contrast, passive immune serum therapy, while increasing the average time of survival of the treated animals, did not protect against death. Specific antibodies in immune sera were not found to exert any increased in vitro bactericidal activities on P. tularensis. It was concluded from these studies that cellular factors probably constitute the principal mechanism of host resistance in both normal and immunized animals infected with P. tularensis. Extracellular specific antibodies appear to contribute to resistance to a lesser extent in acquired immunity, yet the two factors in vivo complement each other and are difficult, if not impossible, to separate., Doctor of Philosophy; |
Authors
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Thorpe, Bert Duane; |
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Contributors
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Pathology;, School of Medicine;, University of Utah |
Publication Detail
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Publisher : University of Utah Type : text, thesis; Format : application/pdf |
Date Detail
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1963-06 |
Subject
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Host-Parasite relations;, Immunity; Francisella; Francisella tularensis; |
Coverage
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- |
Relation
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Digital reproduction of “Mechanisms of resistance in Pasteurella tularensis infections..” Spencer S. Eccles Health Sciences Library. <br><br> Print version of “Mechanisms of resistance in Pasteurella tularensis infections.” available at J. Willard Marriott Library Special Collection. QR6.5 1963 .T47. |
Source
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Original: University of Utah Spencer S. Eccles Health Sciences Library (no longer available). |
Copyright Information
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© Bert Duane Thorpe. |
Other Details
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Languages : eng; |
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