IgG antibody binding to the outer surface of infective larvae of Ancylostoma caninum

Applying the indirect fluorescent antibody technique to the infective stages of the hookworm Ancylostoma caninum, it appeared that they do not show IgG antibody binding when serum from dogs infected with A. caninum was used in the test (antiserum). However, inhibiting these stages metabolically with azide or with low temperatures, IgG antibody binding to the outer surface was observed. When the inhibitory factors were removed, shedding of fluorescent substances was seen, which were obviously coming from the outer surface of the larvae. This suggests that shedding of the antigen might occur.