Iscom (immunostimulating complex) vaccines containing mono- or polyvalent pili of enterotoxigenic E. coli; immune response of rabbit and swine

Passive immunity in cattle against enterotoxigenic Escherichia coli: serologic evaluation of a bacterin containing K99 and F41 fimbriae in colostrum of vaccinated females and calf serum

A bacterin from enterotoxigenic Escherichia coli (ETEC), containing fimbriae K99 and F41, was produced and its capacity to induce anti-K99 and anti-F41 antibodies in colostrum of vaccinated cows and in calf serum, and the persistence of these antibodies in neonates were determined. Three experiments were performed on two commercial farms. In all experiments animals were allotted randomly to the blocks, each block consisting of two pregnant females (a vaccinated one and a control one) and their respective calves. In experiment A (farm 1), comprised of 18 blocks, the animals received a vaccine dose 30 days before delivery. In experiment B (farm 1), consisted of 26 blocks, the animals received two vaccine doses (60 and 30 days before delivery). In experiment C (farm 2), consisted of 22 blocks, the animals received two vaccine doses (60 and 30 days before delivery). In experiments A and B pregnant cows and heifers were used and colostrum and serum from 24- to 36-hour-old calves were collected. In experiment C, pregnant embryo-recipient heifers were used and colostrum and sera from calves at 7, 14, 28 and 42 days of age were collected. Anti-K99 and anti-F41 antibodies were detected by ELISA using purified K99 and F41 fimbrial antigens. In experiment A no difference between treated and control groups was observed for the concentration of anti-K99 and anti-F41 antibodies in colostrum and calf serum. In experiment B a difference (P<0.001) was observed for colostrum of vaccinated females and for serum of their calves. In experiment C, difference between vaccinated and control animals was observed for colostrum and calf serum at 7, 14, 28 (P<0.001 in all cases) and 42 days of age (P= 0.003). The results showed the efficiency of the bacterin to induce detectable humoral immune response.

Immune stimulating complexes as mucosal vaccines

There is a need for non-living adjuvant vectors that will allow a full range of local and systemic immune responses to orally administered purified antigens. Here we describe our experience with lipophilic immune-stimulating complexes (ISCOMs) containing the saponin adjuvant Quil A. When given orally, ISCOMs containing the model protein antigen ovalbumin (OVA) induce a wide range of systemic immune responses, including Th1 and Th2 CD4-dependent activity, serum IgG antibodies and class I MHC-restricted cytotoxic T cell responses. In addition, there is local production of secretory IgA antibodies in the intestine itself, as well as priming of CD4 and CD8 T cell responses in the draining lymphoid tissues. Preliminary results indicate that the mucosal adjuvant properties of ISCOMs may reflect their ability to deliver antigen combined with the pro-inflammatory properties of Quil A in a particulate form. Of the many inflammatory mediators induced, interleukin-12, derived from dendritic cells and/or macrophages, appears to be of central importance. These results indicate that ISCOMs may prove to be useful mucosal vaccine vectors with functions which are distinct from existing vectors of this type.