Alginate-chitosan microcapsules improve vaccine potential of gamma-irradiated Listeria monocytogenes against listeriosis in murine model.

Listeria monocytogenes is a cause of infectious food-borne disease in humans, characterized by neurological manifestations, abortion, and neonatal septicemia. It is intracellular bacterium, which limits the development of protective inactivated vacines. Adjuvants capable of stimulating cellular immune response are important tools for developing novel vaccines against intracellular bacteria. The aim of this study was to evaluate the vaccine potential of L. monocytogenes inactivated by gamma irradiation (KLM-γ) encapsulated in alginate microcapsules associated or not with chitosan against listeriosis in the murine model. At the fourth day after challenge there was a reduction in bacterial recovery in mice vaccinated with KLM-γ encapsulated with alginate or alginate-chitosan, with lower bacterial loads in the spleen (10 fold) and liver (100 fold) when compared to non-vaccinated mice. In vitro stimulation of splenocytes from mice vaccinated with alginate-chitosan-encapsulated KLM-γ resulted in lymphocyte proliferation, increase of proportion of memory CD4+ and CD8+ T cell and production of IL-10 and IFN-γ. Interestingly, the group vaccinated with alginate-chitosan-encapsulated KLM-γ had increased survival to lethal infection with lower L. monocytogenes-induced hepatic inflammation and necrosis. Therefore, KLM-γ encapsulation with alginate-chitosan proved to have potential for development of novel and safe inactivated vaccine formulations against listeriosis.

Diagnosis of canine brucellosis: comparison of various serologic tests and PCR.

Canine brucellosis is an infectious and contagious disease associated with reproductive losses in breeding kennels. As a zoonotic disease, it poses a risk to human health, especially for veterinarians and breeders who handle materials potentially contaminated with Brucella canis. However, canine brucellosis is a neglected and underestimated disease given the difficulties in establishing a definitive diagnosis. We evaluated the frequency of detection of B. canis in 5 breeding kennels by using various serologic methods and PCR. Circulation of B. canis in these kennels was confirmed by bacterial isolation. The frequency of positive serologic results varied from 6.3% by AGID to 16.5% by dot-ELISA. There was no positive serology for smooth Brucella. PCR testing was positive in 13.9% of samples. The only detection tests with reasonable agreement were PCR and 2ME-MAT. The diagnosis of canine brucellosis remains challenging. The use of a single laboratory method, or even the use of different laboratory methods, may not be sufficient to reach a definitive diagnosis.