A cold precipitable fibrinogen complex in the plasma of cattle dying from infection with Babesia argentina.

Plasma from cattle dying from infection with Babesia argentina formed a cold precipitable gel when stored at 4 degrees C. Immunodiffusion and electrophoresis showed the soluble phase of the gel to consist mainly of a fibrinogen-like protein with small amounts of other plasma proteins. Gel filtration and specific clotting assays demonstrated a wide molecular weight spectrum of fibrinogen-like proteins, most of which appeared to be soluble fibrin in either monomer or complex forms. The possibility that proteolytic enzymes might be responsible for the formation of the gel is discussed.