. Immunological findings associated with Argentinean strains of Mycobacterium avium subsp. paratuberculosis in bovine models.

JOLLY, A; COLAVECCHIA, SB.; FERNANDEZ, B; HAJOS S; PAOLICCHI, F.A.; MINATEL, L.; MUNDO, S. L.

VETERINARY IMMUNOLOGY AND IMMUNOPATHOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 176 p. 28 - 33

0165-2427

tMycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of ruminant paratubercu-losis. The aim of this study was to evaluate the biological behavior of different Argentinean strains of MAPin two bovine infection models: macrophage (in vitro) and calf (in vivo) through the evaluation of earlyimmune responses at the peripheral and local levels. Two MAP strains (A and C) were selected taking intoaccount the different patterns of TNF- and IL-10 secretion displayed by infected bovine macrophagesin vitro. Two groups of calves were infected with 250 mg of total wet weight live MAP: strain A infectedgroup (MA, n = 3), strain C infected group (MC, n = 2). Another group of animals was mock-infected (MI,n = 3). Infection was confirmed by MAP culture of feces and microscopic observation of granulomatouslesions in the gut tissue. All infected calves showed positive results in the DTH skin test. A significantincrease in peripheral CD4CD25+cells in MC group on day 150 was detected. The specific cellular immuneresponse developed allowed the identification of the infection as early as 30 days in the MA group. How-ever, the percentage of CD8CD25+cells was significantly increased on day 120 in MC group. Significantdifferences between groups in proliferation and cellular responses were also detected in ileocecal lymphnode samples. In summary, the strains of MAP employed herein induced differential immune responsesin peripheral cells, in the proliferative responses and in cell functionality at the local level. Our findingssupport the hypotheses that the in vitro behavior displayed by macrophages could be a tool to identifydifferences among MAP strains infecting bovines and that the host-pathogen interactions occurring uponinfection are dependent on the strain of MAP involved.