ABSTRACT
Antibody-mediated immune response (AMIR) to ovalbumin (OVA) or hen-egg white lysozyme (HEWL) and cell-mediated immune response (CMIR) such as delayed-type hypersensitivity (DTH) to mycobacteria have been proposed as quantitative traits for selective breeding to improve animal health. However, DTH to mycobacteria may confound diagnosis of tuberculosis in cattle. Candida albicans, a yeast also known to induce DTH, was tested as an alternative for DTH induction and testing since it is not a target of regulatory diagnostic tests. Other objectives were to determine if both AMIR and CMIR in cattle receiving Quil A as adjuvant were equivalent to corresponding responses induced by Freund's complete adjuvant (FCA). Forty lactating Holstein cows were randomly assigned to two treatment groups, which received ovalbumin (OVA) and C. albicans adjuvanted with FCA and Freund's incomplete adjuvant (FIA) on days 0 and 14, respectively, or Quil A on days 0 and 14. The FCA was used as adjuvant and as a source of Mycobacterium tuberculosis-induced DTH. Testing for DTH was performed on day 21 with killed C. albicans whole cell (CaWC), a purified extract from C. albicans (candin) and M. phlei purified protein (phlein). Both primary and secondary antibody responses to OVA were statistically significant and similar in both FCA and Quil A treatment groups. No significant differences were detected in immunoglobulin G (IgG) isotypic-mediated responses to OVA or candin between groups. C. albicans adjuvanted with Quil A induced DTH reaction similar to those induced by C. albicans and mycobacteria in FCA.
