Functional and antigenic maturation of Brugia malayi microfilariae.

Brugia malayi microfilariae of specified ages were obtained from gerbils implanted with fertile adult worms. Such microfilariae were tested for their capacity to infect mosquitoes. A strong age dependence was found for the microfilariae's capacity to: penetrate the mosquito midgut, exsheath in response to 20 mM calcium, and develop to third stage larvae in the mosquito. In addition, differences were found between 2-day-old microfilariae and controls (from larva-infected gerbils) in their reactivities with a series of monoclonal antibodies. Thus, defined immunochemical changes occur in microfilariae as they assume functional maturity.