The effect of pasteurization on the amount of Mycobacterium avium subspecies paratuberculosis in colostrum

Abstract

Colostrum plays an important role in the transmission of Johne’s disease to calves. Pasteurization of colostrum is an effective way to reduce this risk. Literature showed that a pasteurization at 60°C for 60 minutes gave the best results of reducing the concentration of Mycobacterium avium subspecies paratuberculosis and keeping IgG concentrations high. Most pasteurization studies use a culturing method for detecting differences in pre and post pasteurization samples. The disadvantage of this method is the duration of culture and the relatively high detection limit. Also PCR is used for detecting MAP in colostrum. The disadvantage of this method is the impossibility of making difference between viable and unviable MAP bacteria. In this research a fundament was established for creating a new diagnostic method, based on the differentiation between the MAP specific F57 gene and MbtA gene, by using a restriction enzyme to cut the MbtA gene. The difference between MbtA/F57 ratio of pre and post pasteurization samples will tell the difference of viable/unviable MAP bacteria. Electrophoresis and rtPCR were used in the experiments. Two restriction enzymes proofed to be useful for cutting the pure MbtA gene: Not-1 and Hinf-1. The best results for cutting the pure MbtA gene were given by the Hinf-1 restriction enzyme. Further experiments are required for the development of a new diagnostic method to make the difference between viable and unviable MAP bacteria after pasteurization.