TERMINAL STAGE OF TUBERCULOUS PROCESS IN GUINEA PIGS

Heterogeneous cultures of Mycobacterium tuberculosis in their nominal cellular form induce a specific infectious process in genetically and immunologically heterogeneous populations of guinea pigs, with variations in symptomatic manifestations and in the severity of pathognomonic pathological changes. The most characteristic indicators of the tbc genotype in guinea pigs include tuberculous phthisis and severe lesions of the spleen and liver, with death occurring within 4 to 12 weeks. Antigenic activity of cultures can vary significantly, and lethality may occur as a delayed biological event. L-transformed variants of the pathogen can cause atypical tuberculosis progression, even in the most sensitive laboratory models – up to non-pathogenicity and antigenic are activity in the first passages through guinea pigs – resulting in false-negative diagnoses and facilitating the spread of the emergent infection over time and space. Among physiologically randomized guinea pigs, the tuberculosis process induced by a pathogenic field strain of bovine mycobacteria followed a typical subacute course. This included a strong cutaneous allergic reaction to tuberculin, tuberculous phthisis, severe pathological lesions in the spleen and liver, and irregular miliary tuberculosis changes in the lungs. Morpho-biochemical indicators showed a complete depletion of the body’s defense and compensatory mechanisms and a pathological state incompatible with continued life. Despite the progression of the tuberculosis process, guinea pigs did not exhibit outward clinical signs of a fatal infection until 3–5 days before death caused by tuberculous intoxication, exhaustion, and degenerative-inflammatory destruction of internal organs. They remained fairly active, responsive, and had a good appetite until the terminal stage, consuming all food and showing interest in dietary feed until the last moments. Emaciation became noticeable by the 3rd or 4th week of the pathological process. Notably, cell-mediated immune responses were not dependent on the animals’ physiological state and remained informative.