Experimental Infection with Yersinia Pseudotuberculosis of Ground Squirrels (Citellus Citellus)

Abstract

Summary An experimental infection was induced in the European ground squirrel (Citellus citellus) by intraperitoneally injecting of 1 ml. of microbial suspension, containing 1 times 109 CFU (colony forming units) of Yersinia pseudotuberculosis, serotypes I and III. The infectious process was dynamically followed up from the 1st up to the 30th day, respectively. Account was rendered to the general condition, the internal body temperature and the mortality rate. The phagocytic activity of alveolar macrophages (aMa) and polymorphonuclear leucocytes (PMNL), isolated from the experimental animals, was also determined, as well as the degree of bacterial dissemination into the viscera and the histomorphological changes that found in the parenchymal organs. These investigations confirm the fact that the bacterial agent has a broad spectrum of alaterations in the organism of the host ‐ the European ground squirrel (Citellus citellus) in which the pseudotuberculosis developes as a generalized infection, especially pronounced in the animals that were infected with the serotype III.

Attenuation and Preserved Immunogenic Potential of Yersinia pseudotuberculosis Mutant Strains Evidenced in Oral Pig Model

“…Other studies (Logsdon and Mecsas, 2003) revealed that a yopH mutant of Y. pseudotuberculosis also fails to colonize the MLN at orogastrical murine model. Moreover, Balada‐Llasat and Mecsas (2006) reported lymphadenitis with multiple necrotic foci in MLN at intragastral infection of mice, similarly to our previous investigation on ground squirrels (Veljanov et al., 1993), where small necrotic and necrobiotic foci were found in liver, spleen and MLN. Surprisingly, no morphological changes were detected 2–4 weeks after intraperitoneal infection of ground squirrels with Y. pseudotuberculosis serotype O:1.…”

Isolation of Pathogenic Yersiniae from Wild Animals in Bulgaria

“…All animals were killed during winter hunting and probably our ®ndings represent latent infections, when bacterial cells are disseminated by the blood and lymph routes to the viscera. Bacterial dissemination to the viscera was shown in our earlier investigations of experimental Yersinia infection (Veljanov et al, 1993;Markova et al, 1994;Nikolova and Vesselinova, 1995;Nikolova et al, 1997;Najdenski et al, 1998).…”

Experimental Infections with Wild and Mutant Yersinia pseudotuberculosis Strains in Rabbits

“…Evidently, rats are quite resistant to Y. pseudotuberculosis infection, in contrast to European ground squirrels which are more sensitive and i.p. challenge of 1.0 · 10 9 CFU caused lethal infection within a week (Veljanov et al, 1993). Histological examinations of rabbits infected with both wild-type and mutant Y. pseudotuberculosis strains showed the same changes in viscera as to those found in the ground squirrel model (Veljanov et al, 1993).…”

“…Evidently, rats are quite resistant to Y. pseudotuberculosis infection, in contrast to European ground squirrels which are more sensitive and i.p. challenge of 1.0 × 10 9 CFU caused lethal infection within a week (Veljanov et al., 1993).…”

“…Histological examinations of rabbits infected with both wild‐type and mutant Y. pseudotuberculosis strains showed the same changes in viscera as to those found in the ground squirrel model (Veljanov et al., 1993). We observed after infection with Y. pseudotuberculosis serotype O:3 catarrhal pneumonia and necrotic changes in the liver and spleen in contrast to the rabbit model where no necrotic foci were observed.…”