Three doses of 100 l of vaccine (test groups containing 5 g of Bm86) were sub-cutaneously injected at 0, 10 and 20 days. the efficacy of formulations in cattle. Good correlation was established between the level of antibodies in mice and cattle, and between the amount of anti -Bm86 IgG1 in mice and the degree of protection in cattle. == Conclusion == Mouse model have the potential to predict immunogenicity and efficacy of formulations in cattle. These results also support the use of the yeast expression system for recombinant vaccine formulations, enabling the prediction of more cost – effective formulations. == Background == In the last seven decades, a great number of studies have been devoted to the use of adjuvants to potentiate the immune response to antigens. These efforts have been particularly important in recent years with the development of synthetic, purified subunit and recombinant vaccines, which are generally WYC-209 poor immunogens. Recent studies describe the advantages of using saponin over oil emulsions, even though latter still constitutes the most commercially available adjuvant for veterinary vaccines. Recently, theB. microplusBm86 antigen was isolated and expressed in the yeastP. pastoristo prepare the recombinant vaccine Gavac (Heber Biotec S.A., Havana, Cuba) [1,2]. This vaccine against cattle ticks contains 100 g Bm86 per dose in 2 ml of a Montanide 888 / mineral oil in water emulsion and has proven its efficacy in a large number of controlled and field experiments [2,3,4,5]. However, this vaccine could be further improved by searching for new alternative adjuvants that WYC-209 would induce a stronger long -lasting immune response, and a reduction in production cost. The immunostimulating properties of some components of certain species of yeast have been previously reported [6,7]. The recombinant Bm86 antigen expressed inP. pastorisremains associated to the plasma membrane [1], that surrounds the protein WYC-209 with a hydrophobic environment comparable to that of oil emulsion or liposomes. Taking advantage of this fact, we made several experiments to test the adjuvant effect of fractions of the recombinant yeast in mice [8]. Here, we statement the results obtained when we use yeast derivatives as adjuvants for the immune response in cattle, the analysis of the predictive potential of the mouse model, and the effect of the quality of the immune response on the degree of protection. The membrane of the yeastP. pastoriswas shown to serve as an adjuvant for the humoral immune response in both animal species, adding new advantages to the yeast expression system for the production of recombinant vaccine formulations. == Results == == Experiment I == == Kinetics of the antibody response == Table1shows the results obtained in the quantification by ELISA of the WYC-209 level of anti-Bm86 antibodies in the serum samples from immunized mice [8]. Control groups kept a basal level of Bm86-specific reactivity equal to WYC-209 that of preimmune sera, indicating the specificity of the assays. Mice injected with Bm86 in the membrane plus saponin produced the highest serological response, reaching an immunological peak on day 30. Animals from your Bm86 / cell group showed practically no immunological response against the Bm86 antigen (Table1). == Table 1. == Experiment I. Anti-Bm86 levels in mice immunized according to the experimental groupsa. aTen mice per group were immunized with 5 g Bm86 adjuvated as indicated (Garcia – Garciaet al., 1995). ELISA was used to determine total antibody response against Bm86.Briefly, 100 l of antiserum diluted 1: 100 in PBS were added to the wells, incubated for 2 h at 37C, washed four time with PBST and developed with HRP-conjugated goat anti-mouse IgG as describe in material and methods. Antibody titres were expressed as Ankrd1 the imply absorbance value (O.D.492nm) per group SD (N = 10). == Quality of the immune response.