A comparative study of acetylcholinesterase activity in bovine (S. cervi) and human (B. malayi, W. bancrofti) filaria.

Setaria cervi, a bovine filarial parasite, contains a significant amount of acetylcholinesterase (AChE) activity with microfilaria having five to ten times more AChE activity than female and male adult worms, respectively. Because AChE shows substrate specificity and hydrolyzes acetylthiocholine but not butrylthiocholine, this parasitic enzyme is likely a true acetylcholinesterase. The latter also resembles an AChE enzyme in the human filarial parasite B. malayi which hydrolyzes acetylthiocholine iodide three times faster than butrylthiocholine iodide. The S. cervi AChE, like its counterpart, also exhibit inhibition with eserine, a specific inhibitor of this enzyme. Subcellular localization of AChE in adult female worms shows enzyme activity both in the mitochondrial and post-mitochondrial fraction. However, enzyme activity in the soluble fraction is twenty-seven times greater than in the mitochondrial fraction.