Protective antigens in fractions of adult Nematospiroides dubius.

Adult Nematospiroides dubius crude soluble homogenate consistently produced five fractions (F1-5) after filtration through Sephadex G-200 with molecular weights of greater than 300,000, 240,000, 83,000, 31,000 and less than 10,000. The high molecular weight F1 and F2 reacted strongly with serum from previously infected mice in ELISA. Protective immunity was associated with F1 N. dubius immunogens (molecular weight greater than 300,000). Immunization with smaller molecular weight fractions also reduced worm recoveries following challenge infections but to a lesser extent.