Differences in the immune responses in lambs and kids vaccinated against paratuberculosis, according to the age of vaccination

In order to evaluate and compare the peripheral immune responses induced by the vaccination against paratuberculosis in relation with the age of immun ization, two groups of lambs and goat kids were vaccinated at 15 days and 5 months old, respectively. A heat-killed commercial vaccine was inoculated subcutaneously and humoral and cellular immune responses were measured by a n ELISA and IFN-gamma assay, respectively, at 0, 30, 90, 180, 270 and 360 d pv in the lambs and 0, 30, 90 and 180 dpv in the caprine. IFN-gamma values did not show statistically significant differences between both groups, but when compared to the unvaccinated controls, this cytokine response tend to disappear earlier in animals vaccinated at 15 days old. The antibody respo nse was always higher and more persistent in animals vaccinated at 5 months . The possibility of the incomplete degree of maturation of the immune syst em in 15 days old animals as the cause of the differences in the immune res ponse to vaccination is suggested. (C) 2000 Elsevier Science B.V. All right s reserved.