TABLE 3.

IFN-γ responses by reindeer from a TB-free herd in Wisconsin^a

Stimulant	IFN-γ, OD (mean ± SEM)	No. of responses of >0.1 ΔOD
None	0.092 ± 0.010	Not applicable
M. avium PPD	0.086 ± 0.003	0
M. bovis PPD	0.091 ± 0.006	1
rESAT-6-CFP-10	0.098 ± 0.005	0
PWM	1.526 ± 0.128	38

^aHeparinized blood samples were obtained from 38 reindeer in a TB-free herd in Milltown, WI, and shipped to NADC, Ames, IA, overnight (24-h delay prior to setup). Blood was dispensed in 1.5-ml aliquots into individual wells of a 24-well plate. Treatments included no stimulation (PBS), M. avium PPD (40 μg/ml), M. bovis PPD (40 μg/ml), rESAT-6-CFP-10 (10 μg/ml), or PWM (20 μg/ml). Blood cultures were incubated for 48 h, plasma was harvested, and IFN-γ concentrations were determined using an ELISA-based kit (Cervigam; Pfizer Animal Health). Absorbencies of standards and test samples were read at 450 nm using an ELISA plate reader. Duplicate samples for individual treatments were analyzed. ΔOD is calculated as response to antigen or mitogen stimulation minus response to no stimulation.