Stimulated enrichment of Clostridium difficile specific IgA in mature cow's milk.

Cow milk products enriched with Clostridium difficile (C. diff.) specific IgA are possible alternative therapeutics against C. diff. associated diarrhea. A persistently high level of C. diff. specific IgA in mature milk triggered by continuous immunizations of dairy cows against C. diff. was hypothesized. Nine Brown Swiss cows were repeatedly vaccinated against C. diff. and divided into low responder (LR) and high responder (HR) cows, as measured by their production of anti-C. diff. specific IgA in milk (threshold: 8.0 μg anti-C. diff. specific IgA/mL on average). Total and C. diff. specific IgA were quantified in bovine milk and blood using a sandwich ELISA. Important milk production factors were analyzed per lactation stage. Milk yield, milk fats and proteins were significantly different (P < 0.05) in the early lactation stage when the treated with the untreated cows (n = 30) were compared. In contrast to the "before treatment control" values, the HR's milk anti-C. diff. IgA was approximately 80% higher at any lactation stage, and the HR's total milk IgA increased up to 72% in the late lactation stage. The LR's total milk IgA differed from the baseline by roughly 47% only in the late lactation stage. The total and specific IgA contents in milk were more influenced by the anti-C. diff. immunizations than in blood. The correlations between anti-C. diff. specific IgA, total IgA and the main production factors in milk were classified as weak (I r I < 0.5), except for the close relation of anti-C. diff. specific IgA and total IgA (r = 0.69). To conclude, a sustainable C. diff. specific IgA enrichment in milk can be achieved by continuous immunization of dairy cows, provided a potent and well-formulated anti-C. diff. vaccine is given to dairy cows preselected due to their proven anti-C. diff. receptivity.