COMPARISON OF A VARIETY OF ADJUVANTS IN DAIRY CATTLE
This project aimed at identifying adjuvants better or equivalent to the UdeS adjuvant (EmulsigenD + CpG+ Indolicidin) that was used in the previous evaluations of the UdeS vaccine.
Seventy nine cattle (40 dairy cows and 39 heifers) were divided into 8 groups of 10, at the exception of one group of 9. Each group received a different adjuvant: UdeS (positive control), EmulsigenD, EmulsigenD + CpG, EmulsigenD + pDNA Bay98, EmulsigenDL90, Zelnate, Montanide ISA 61VG + QuilA, Montanide ISA 201VG. Animals were immunized twice subcutaneously in the side of the neck 10 weeks apart. Blood samples were collected every week over a 16 week period to monitor total IgG, IgG1 and IgG2 in the serum. Milk samples were collected at the same frequency for the dairy cow to monitor the same immunoglobulins in the skimmed milk. Larger blood samples were collected before the first immunization and 4 weeks after the second immunization to isolate the lymphocytes and then evaluate their antigen specific proliferation in particular for the CD4+ and CD8+ lymphocytes. Every other week, assessment of the inflammation at the injection site was performed by measuring the size of the masses.
To help the comparison of the adjuvants, the different parameters were classified as required or nice-to-have. The required parameters are the antigen specific CD4+ and CD8+ proliferation, the serum antigen specific total IgG, IgG2 IgG1/IgG2 ratio. The nice-to-have parameters are the serum antigen specific IgG1, milk antigen specific total IgG, IgG1, IgG2.
Among the vaccine formulations with new adjuvants tested in this study, four formulations have induced immune responses that were higher or equivalent to that obtained with the original UdeS vaccine composition: Montanide ISA 61VG + QuilA, Montanide ISA 201 VG, EmulsigenD + CpG, and EmulsigenD + pDNA Bay98. Mild local reactions were observed at least in singular animals of all groups, reactions of moderate nature only in one animal of the Zelnate vaccine group, and a strong local inflammation in almost all animals of the Montanide ISA 61 + QuilA group.