Francisco Suárez Güemes

Presencia de aborto y mortinatos en cabras inmunizadas

The presence of abortions was evaluated in brucellosis-vaccinated goats in endemic zones. In total, 243 goats under extensive management conditions were used, 57 goats were vaccinated with RB51 at the dose rate of 1 x 1010 colony-forming units (cfu)/ml, 68 goats received 1 x 109 cfu rfbK, 97 goats received 1 x 105 cfu Rev 1, and 21 goats were kept as non-vaccinated controls. One hundred thirty nine (139) goats were detected pregnant, resulting in the following pregnancy rates: 40.3 % (23/ 57) for RB51, 66.2 % (45/68) rfbK, 46.4 % (45/97) for Rev 1, and 85.7 % (18/21) for the non-vaccinated controls. Abortion rates were as follows: RB51: 74.1 % (23/31), rfbK: 35.5 % (16/45), Rev 1: 22.2 % (0/45), and non-vaccinated controls: 16.6% (3/18). The RB51 strain was isolated from one aborted fetus. The relative risk of abortion was as follows: RB51: 4.45, rfbK: 2.13, and Rev 1: 1.33. In addition, goats in a herd with excellent nutritional conditions were also vaccinated, as follows: 10 with 1 x 1010 cfu RB51, 10 with 1 x 109 cfu rfbK, 10 with 1 x 105 cfu Rev 1, and 9 goats remained as non-vaccinated controls. The RB51 group had one abortion and one stillborn kid. In both cases, the RB51 strain was isolated from the fetuses and vaginal exudates. It was concluded that among the immunogens evaluated in goats, the RB51 strain vaccine is not an adequate option, since it results in abortions and stillbirths.

Producción de interferón gamma en cultivos de sangre completa en respuesta a antígenos de Brucella abortus en bovinos vacunados con RB51

In order to evaluate the interferon gamma (IFN-g) induction ability of different proteic preparations and that of Brucella abortus smooth and rough lipopolysaccharides in whole blood cultures from RB51-immunized cattle, both vaccinated and revaccinated cattle were selected from a herd with high brucellosis prevalence. The assay was validated using a group of serologically-negative cattle from a control herd. Whole blood cultures were stimulated with the different antigens and the mitogen concanavalin A, for 24 h at 37 oC. Plasma supernatants were collected to evaluate the IFN-g released, using a commercially-available sandwich ELISA kit. Results expressed as stimulation indexes showed a higher cytokine-inducing ability for the sonicated extract followed by cytosol proteins and inner membrane protein, for the different groups. Nevertheless, even though boosted, serologically-positive animal showed a significant response lower than that observed in the serologically-negative groups, probably due to a shift in the prevalence of B. abortus antigen-responsive cell subpopulations, indirectly revealed by the presence of high antibody levels. Therefore, the usefulness of estimating IFN-g release after the in vitro stimulation of whole blood cultures with a sonicated B. abortus extract for the evaluation and follow up of cellular immunity in vaccinated cows was demonstrated.