Tailor-made plasmin substrates as a new parameter for the diagnosis of clinical mastitis in dairy cattle

Abstract

Mastitis in dairy cattle is a major problem worldwide and is known to be one of the most costly diseases. Currently, there are several methodologies on the market to diagnose mastitis, however these are not optimal for the use in practice due to high costs and low sensitivity and specificity. The newly developed plasmin-test could provide a solution as a supplement for the current methodologies. The aims of this study are to develop a new test using plasmin-level determination by (1) identifying the optimal substrate, substrate concentration and buffer of a FRET-based plasmin detection and (2) to assess the effect of a freeze-thaw process on plasmin levels as determined with this technique. From the results it can be concluded that the optimal substrate is the RR substrate in a buffer of Tris and Gelatine. The optimal substrate concentration lies between 10 and 16 µM. With regard to the freeze and thaw process, the results from the correlation test show that there is a positive correlation of 0,142 (p = 0,058) between the fresh and the frozen samples. There is only a small coherence between the fresh and frozen samples. Further research is necessary to make a reliable statement regarding the freeze and thaw process