Serologic and enzymatic investigations of Trichinella spiralis II. Characterization of larval lactic dehydrogenase

Abstract

A comparison has been made between lactic dehydrogenase (LDH) of extracts of Trinchinella spiralis larvae and pooled sera from normal rabbits and animals 8 weeks postinfection. Polyacrylamide gel electrophoresis demonstrated differences between the LDH isozymes of the parasite and those separated in the sera from normal and infected rabbits. The pH optimum of the parasite LDH was observed at 9.0, while optimal enzymatic activity of the sera enzymes was demonstrated at pH 10.5. It was shown that the larval LDH was considerably more heat stable than the serum enzyme of either the normal or trichina-infected rabbits. Differences in the inhibitory effects of several divalent cations were demonstrated between the enzyme of Trichinella extract and that from sera from normal and infected rabbits. Serological studies did not show cross-reactions between the rabbit and larval LDH by antibodies made by the rabbit. An isozyme found in the larvae was demonstrated in the adult worms. These studies indicate basic differences between physicochemical properties of the LDH of the parasite and the rabbit sera.