The in vitro culture of Onchocerca spp.: II. The excretory/secretory products of the first and third stage larvae of Onchocerca lienalis and O. ochengi.

The developing first and third larval stages of two bovine Onchocerca species were maintained in vitro in the presence of 35S-methionine, following their initial development in the vector species Simulium ornatum s.1. to characterise the expression and secretion of their metabolites. The first larval stages of O. lienalis and O. ochengi did not release any E/S products. In contrast the supernatants of the third stage larvae of both species contained a double band of 21 and 20 kDa for O. ochengi and 23 and 22 kDa bands for O. lienalis when kept at room temperature. A temperature shift to 37 degrees C led to the increased expression of the 23 kDa protein with the infective larvae of O. lienalis. The possible role of these molecules is discussed.