Role of Yersinia pseudotuberculosis outer proteins (Yops) in murine humoral immune response

Abstract

The infection of mice with the wild-type (WT) strain of Y. pseudotuberculosis did not induce polyclonal activation of B lymphocytes. Suppression in the production of certain isotypes of Ig was observed, provoked mainly by YopH, YopJ and YpkA. The WT strain induced a progressive increase in the serum-specific IgG, which peaked after 4 weeks after infection, IgM being produced only after 1 week. Autoantibodies against phosphorylcholine, myelin, thyroglobulin and cardiolipin could be detected in the serum of mice infected with the WT strain. The infection of mice provoked suppression in the production of immunoglobulins by splenic B cells and that YopH, YopJ and YpkA must be involved here.

YopJ-Promoted Cytotoxicity and Systemic Colonization Are Associated with High Levels of Murine Interleukin-18, Gamma Interferon, and Neutrophils in a Live Vaccine Model ofYersinia pseudotuberculosisInfection

“…Results of previous studies have suggested that YopJ/P activity can inhibit the development of adaptive immune responses in mice infected with Yersinia (32,37,65,67). However, a caveat of these previous studies is that immune responses in mice infected with yopJ or yopP mutant strains were compared to those of mice infected with other attenuated Yersinia strains but not to those infected with wild-type strains (32,37,65,67).…”

“…Thus, although YopJ/P plays a reproducible role in systemic colonization following bacterial spread from the intestinal tract, its role in virulence remains variable and likely will depend heavily on the conditions of the experiment, including, most critically, the strains of Yersinia and mice used. On the other hand, evidence is accumulating that YopJ activity is not required for virulence or tissue colonization by Y. pestis in bubonic, pneumonic, or septicemic plague models (33,63,73,74) or Y. pseudotuberculosis when mice are infected by a route (e.g., intraperitoneal or intravenous) that bypasses the intestinal phase (2,37). Why YopJ/P specifically promotes systemic colonization following intestinal Yersinia infection is unclear.…”

“…However, a caveat of these previous studies is that immune responses in mice infected with yopJ or yopP mutant strains were compared to those of mice infected with other attenuated Yersinia strains but not to those infected with wild-type strains (32,37,65,67). By establishing a sublethal infection model, we overcame the problem encountered in previous studies, namely, that doses used for infection of mice would be lethal for mice infected with wild-type strains.…”