A possible deficiency of cell-mediated immunity in the opossum, Trichosurus vulpecula, in relation to tuberculosis

Authors: Moriarty KM
Publication: New Zealand Veterinary Journal, Volume 21, Issue 8, pp 167-169, Aug 1973
Publisher: Taylor and Francis

Animal type: Possum, Wildlife
Subject Terms: Bacterial, Immune system/immunology, Mycobacterial, Disease/defect, Zoonosis, Infectious disease, Public health
Article class: Scientific Article

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Abstract: The Australian opossum, Trichosrus vulpecula, is susceptible to experimental infection with both human and bovine strains of Mycobacterium tuberculosis (Bollinger and Bollinger, 1948). Naturally occurring infections of M. bovis have been reported in opossums in New Zealand (Ekdahl et al 1970). Smith (1972) has described the lesions seen in such infections as being generalized, suppurative and associated with sinus formation and has mentioned the epidemiological significance of the disease in these animals. The mechanism of resistance to tuberculosis is not fully understood. While antibodies to tubercle bacilli occur in both tuberculous and normal individuals (Bardana et al 1973) immunity to the disease is considered to be associated with cell-mediated, rather than antibody-mediated, mechanisms (Anon., 1969). Several in vitro correlates of cell-mediated immunity are recognized (Bloom and Glade, 1971), one of which is lymphocyte transformation (see Ling, 1968). Lymphocyte transformation refers to the morohological and biochemical changes which occur in lymphocytes either specifically in response to antigens, or nonsnecifically in response to certain mitogens. The non-specific mitogens used are generally of slant origin, the most common being phytohaemagglutinin (PHA), an extract of the seeds of the jack bean, Phaseolus vulgaris. Transformation is measured by incubating cells with PHA for various periods before adding a suitable radioactive substrate. If cells are transforming, the substrate is used in nucleic acid synthesis and the amount incorporated by the cells is determined bv liquid scintillation counting. The extent to which cells in a lymphocyte culture transform provides an index of the cell population`s ability to engage in cell- mediated immunity reactions (Bloom, 1971). The present study compares the degree of transformation occurring in cultures of opossum and rabbit spleen cells in response to PHA.

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