ROTAVIRUS INHIBITOR AND RECOVERY IN RAW BOVINE-MILK

Milk could be a vector for viruses contaminating the human gut, but de tection of rotavirus in raw bovine milk is prevented by the presence o f a very active antiviral substance. Rotavirus inhibition by various m ilk samples and the nature of the inhibitor were examined, and an impr oved method for rotavirus detection in raw bovine milk was designed. M ost milk samples from cows near Toulouse, France, could inhibit 5 x 10 (6) PFU/ml of rotavirus, with wide variations among individuals and wi th time. The rotavirus inhibitor was bound on a protein G affinity col umn, and corresponded to the immunoglobulin G fraction (IgG) as shown by enzymatic immunoassay. The proposed method for rotavirus detection requires the action of HCl (pH 3) and dithiothreitol(0.01 M) for 10 mi n before PFU counts on cell cultures. This treatment improved the dete ction threshold 1,000-fold, and the recovery of rotavirus in raw bovin e milk 300-fold.