FIG. 2.

Effects of various formaldehyde concentrations on IgG binding to M. avium subsp. paratuberculosis antigens by SELISA. After formaldehyde treatment, whole M. avium subsp. paratuberculosis bacilli were sonicated for 2 s and the supernatant was used for the SELISA. Solid circles, pool of serum from five cattle that previously tested M. avium subsp. paratuberculosis positive by the FCM; open circles, a pool of serum from five cattle previously tested M. avium subsp. paratuberculosis negative by the FCM; open triangles, no serum. Each data point represents the mean of duplicate experiments. The greatest difference between M. avium subsp. paratuberculosis-positive and -negative serum occurred with the highest concentration of formaldehyde (37%) tested.