[Various mechanisms of formation of chronic tularemia in highly-sensitive animal species (Microtus rossiae-meridionalis)].

Experiments on voles belonging to the tularemia-sensitive species Microtus rossiae-Meridionalis, infected with Francisella tularensis highly virulent strain 503, have been carried out with the aim of studying the pathogenesis of chronic tularemia. The experiments have been made with the use of live and killed microbial cells. The significance of the multiple oral administration of killed bacteria to voles for the development of the atypical form of infection has been shown.

[Possible atypical course of tularemia (persistence) in the common vole Microtus arvalis Pall].

The possibility of the atypical course of tularemia with the prolonged persistence of Francisella tularensis in common voles (M. arvalis), the twin species of East European voles (M. rossiaemeridionalis), was studied.

Persistence of Francisella tularensis McCoy et Chapin tularemia agent in the organism of highly sensitive rodents after oral infection.

In the literature there are no data on the possibility of obtaining in experiment non-fatal tularemia infection (persistence) in rodents highly sensitive to it (Group I) when using highly virulent strains circulating in nature for infection by natural routes. Our detailed experiments on 1483 adult voles Microtus rossiaemeridionalis Ogn. (syn.

[Processes of bacterial L transformation and L form reversion in the body of argasid ticks].

The experimental infection of tampan ticks (Ornithodoros moubata) with the bacterial cultures of Listeria monocytogenes and Salmonella typhimurium, as well as with their L-forms, was carried out. These experiments demonstrated that both the L-transformation of bacteria and the reversion of their L-forms into the initial bacterial culture could occur in the body of the ticks.

[Experimental latent tularemia in common voles].

Common voles (Microtus subarvalis) were infected with tularemia by feeding them with the corpses of the animals which had been infected with Francisella tularensis strain having somewhat decreased virulence. This resulted in nonlethal infection in 14 out of 433 voles used in the experiment. A considerable part of the animals having had the infection developed bacterial carriership (11 out of 13 animals) with bacteriuria (8 out of 11 animals) lasting up to 2 months.

[Mechanism of the changes in the animal reactivity to tularemia in mixed infection].

Experiments were conducted on albino rats infected with listeria or salmonelloses, and then with tularemia; differences were revealed in the duration of manifestation of nonspecific resistance associated with peculiarities of pathogenesis and immunogenesis of the background infections. One of the significant factors causing an increase of albino rats resistance to tularemia in mixed infection was activation of the immunomorphological reaction promoting accelerated development of specific immunity reactions to this infection.

[Change in phagocytic activity toward the agent of tularemia in highly sensitive animals with mixed infections].

An increase of the ingestive and digestive capacity of neutrophils to the homologous causative agent and tularemia microbe was revealed by the opsonophagocytic test in Microtus arvalis, albino mice and guinea pigs infected with sublethal Yersinia pseudotuberculosis and Salmonella typhimurium doses. In subsequent tularemia infection some of the animals displayed a reduction of the septicemia intensity, prolongation of the disease and elevation of the susceptibility threshold. Period of manifestation of the inhibitory action on tularemia coincided with that of the increase in phagocytic activity

[Further study of the antibody adsorption test for the purpose of increasing the specificity of listeriosis serodiagnosis].

In testing the specificity of interaction in the agglutination reaction with listeria antigens of 191 sera of healthy persons with the aid of adsorption with staphylococcus, enterococcus and listeria a positive result was obtained in 56.5% of cases (108 sera); the higher the serum titres--the more of them reacted specifically (31.7% at the 1 : 40 titre; 83.

[Phagocytic activity of the neutrophils in tularemia in animals with varying infective sensitivity].

A study was made of the ingestive capacity of blood neutrophils; there were revealed no significant differences in the intact animals with a different infectious sensitivity to tularemia. With the development of infection the ingestive activity of leukocytes increased in the infected highly sensitive animals, but the digestive function was not manifest. In albino rats (with a low sensitivity to tularemia) the disease induced an intensification of the ingestive and the manifestation of the digestive function of neutrophils dynamically developing together with the specific immunity reactions.