Abstract
This investigation was conducted to assess the course of antibody formation against various parts of the worm bodies of adult Brugia pahangi filariae by way of an immunofluorescent antibody method using the IgG-, IgM-, and IgE- monoclonal antibodies and sera from infected rats. The results were compared with previous results of a study using the lung fluke (Ohara et al., 1985b),Êin which differences between nematoda and trematoda in terms of immune response and the mechanism of evading the immune response of the host were investigated.

Two weeks after infection, antigenic sites against IgM and IgE antibodies were identified on the outer surfaces of the inner organ, in the body cavity fluid, in muscle layers, on the surfaces of microfilariae in the uterine and excretory canals of the worms. At the same time, we observed a small number of antigenic sites against the IgG antibody around the outer surfaces of the inner organs and in the body cavity fluid of the worms. Thereafter, serum levels of the antibodies against those sites increased until 12 weeks infection.

Antigenic sites against IgG, IgM, and IgE were almost identical; strong antigenicity was found at the sites which contained large amounts of excretory and secretory products, such as in body cavity fluid, inside the excretory canal. On the contrary, no antibody was observed against the cuticle layer throughout the experiment.

The absence of antigenicity on the surface of worm body (cuticle layer) in B.pahangi suggests a strong evasion of the immune response of host and difference in evasive from trematoda.

Key words

Brugia pahangi, Filaria, Nematoda, Antibody, Immunofluorescent method, Antigenicity