Humoral defense of the nematode Ascaris suum: antibacterial, bacteriolytic and agglutinating activities in the body fluid.

Three humoral defense activities (antibacterial, bacteriolytic and agglutinating) were detected in the body fluid of the nematode Ascaris suum. Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) were more sensitive to the antibacterial activity than the Gram-negative bacteria (Escherichia coli). The antibacterial activity was heat stable and was lost by trypsin digestion. The molecular mass of the factor responsible for antibacterial activity was estimated as 6 kDa. The bacteriolytic activity against dried Micrococcus luteus was also detected. The bacteriolytic factor was 6-9 kDa in molecular mass, heat sensitive and trypsin sensitive. Both E. coli and glutaraldehyde-fixed trypsin-treated human A-type red blood cells were agglutinated in the body fluid. An analytical gel permeation HPLC revealed the agglutinating activity consists of at least two factors. Activities of both agglutinating factors were lost by heat treatment or trypsin digestion. The molecular masses estimated for the two agglutinating factors were 500 kDa and 25 kDa. Under experimental conditions, microbe-injection was not a prerequisite for the appearance of these defense activities.