Performance of a Johne's disease enzyme-linked immunosorbent assay adapted for milk samples from goats.

Antibody detection-based tests for paratuberculosis offer speed and economy, 2 diagnostic test attributes important to animal industries with narrow profit margins. Application of such tests to individual milk samples instead of serum samples can further improve testing efficiency and decrease testing cost. Accuracy of a commercial bovine paratuberculosis enzyme-linked immunosorbent assay (ELISA) adapted for use on goat serum and milk samples was determined. Fecal, blood, and milk samples were collected from 159 goats belonging to 2 Wisconsin goat herds with a prior history of paratuberculosis and 1 herd of 50 goats from a paratuberculosis-free Wisconsin herd. Fecal samples were cultured using the modified BACTEC 12B media. Sera were tested according to the manufacturer's instructions for bovine samples. Milk samples were centrifuged and mixed with the ELISA kit's Mycobacterium phlei-containing diluent at a ratio of 1:2. Using fecal culture as the "gold standard," the sensitivity of the ELISA on goat serum was 64% and the sensitivity of the ELISA on goat milk was 48%. The milk ELISA had higher agreement with fecal culture results (kappa = 0.525) than the serum ELISA (kappa = 0.425). ELISA specificity was 100% on both serum and milk. Regression analysis also showed good correlation between serum and milk S/P values (r2 = 0.67). Although less sensitive, the ELISA on goat milk samples appears to offer a useful, low-cost alternative for detection of goats with paratuberculosis that have progressed to the stage of shedding M. paratuberculosis in their feces.     

The effect of active immunization against adrenocorticotropic hormone on cortisol, beta-endorphin, vocalization, and growth in pigs

Because the poor growth performance of intensively housed pigs is associated with increased circulating glucocorticoid concentrations, we investigated the effects of glucocorticoid suppression by inducing a humoral immune response to ACTH on physiological and production variables in growing pigs. Grower pigs (28.6 +/- 0.9 kg) were immunized with amino acids 1 through 24 of ACTH conjugated to ovalbumin and suspended in diethylaminoethyl (DEAE) dextran-adjuvant or adjuvant alone (control) on d 1, 28, and 56. The ACTH-specific antibody titers generated suppressed increases in cortisol concentrations on d 63 in response to an acute stressor (P = 0.002; control = 71 +/- 8.2 ng/mL; ACTH-immune = 43 +/- 4.9 ng/mL) without altering basal concentrations. Plasma beta-endorphin concentrations were also increased (P < 0.001) on d 63 (control = 18 +/- 2.1 ng/mL; ACTH-immune = 63 +/- 7.3 ng/mL), presumably because of a release from negative feedback on the expression of proopiomelanocortin in pituitary corticotropes. Immunization against ACTH did not alter ADG (P = 0.120; control = 1,077 +/- 25; ACTH-immune = 1,143 +/- 25 g) or ADFI (P = 0.64; control = 2,719 +/- 42; ACTH-immune = 2,749 +/- 42 g) and did not modify behavior (P = 0.681) assessed by measuring vocalization in response to acute restraint. In summary, suppression of stress-induced cortisol responses through ACTH immunization increased beta-endorphin concentrations, but it did not modify ADG, ADFI, or restraint vocalization score in growing pigs.     

Testing meningeal strains of Streptococcus suis to detect M protein genes.

Previous reports have suggested that the surface proteins found in meningeal strains of Streptococcus suis might be similar to the M protein of group A streptococci. Fifty-five strains of S suis, including human and swine meningeal and pneumonic isolates, were tested for M protein genes by DNA probes representing the constant domain of the 3' end of the group A, M protein gene. None of the S suis strains examined was positive, indicating that these organisms either lack M protein genes or harbour different genes, not expressing the constant domains of protein M from group A.     

Decreased sensitivity of Sphaerotheca fuliginea to fenarimol and other ergosterol-biosynthesis inhibitors

Decreased sensitivity of Sphaerotheca fuliginea (Schlecht.) Poll. (powdery mildew of cucurbits) to ergosterol-biosynthesis inhibitors (EBIs) which inhibit 14C-demethylation, has been found in areas where these fungicides have been used frequently for several seasons. Relatively low sensitivity was associated with poor disease control in some cases, especially in field-grown cucurbits. Isolates less sensitive to EBIs which inhibit 14C-demethylation were sensitive to fungicides with different modes of action. In order to ensure their continued usefulness it is recommended to reduce selection pressure by using EBIs inhibiting 14C-demethylation during only a part of the growing season.     

Rapid detection of canine parvovirus in feces using monoclonal antibodies and enzyme-linked immunosorbent assay

Monoclonal antibodies were used to develop a double antibody enzyme-linked immunosorbent assay for the detection of canine parvovirus (CPV) antigen in fecal samples. The assay was specific for the hemagglutinating protein of CPV and detected as little as 1.5 ng of virus within a 15-minute incubation period. The use of monoclonal antibodies against 2 epitopes on the CPV antigen permitted the simultaneous addition of test sample and enzyme-conjugated antibody, thus considerably simplifying the manipulations required for the assay. Results were visually determined without special instrumentation. Clinical studies revealed greater than 95% correlation between enzyme-linked immunosorbent assay results and hemagglutination titers.