Objective: To understand the characterization and levels of antibody isotype responses to soluble egg antigen (SEA) and adult worm antigen (AWA) of Schistosoma japonicum in schistosomiasis patients in Poyang Lake region.
Methods: Antibody isotype IgG, IgG1, IgG2, IgG3, IgG4, IgE, IgM and IgA responses to SEA and AWA in the sera of individuals from endemic and non-endemic areas were determined by indirect ELISA.
Results: The levels of antigen-specific antibody isotypes in the sera of patients with egg positive were significantly higher than those of people with egg negative and normal control population from non-endemic area (P < 0.001), and except for anti-SEA IgG2 and anti-AWA IgG4 and IgE antibodies, the levels of antibody isotypes in the sera of people with egg negative in endemic area were significantly higher than those of normal control population from non-endemic area (P < 0.05). In the population with egg positive, children had higher levels of anti-SEA IgM and IgG1 and anti-AWA IgM antibody, and lower AWA specific IgG than adults. There was no significant difference between the male and female except for the male had higher levels of IgG (F = 4.677, P = 0.032) and IgG1 (F = 5.55, P = 0.020)against AWA. Three months post-treatment, the levels of IgG1, IgG3, IgG4 antibody responses to SEA deceased significantly (P < 0.001, P = 0.029, P = 0.044), and almost all the antibody levels decreased significantly (P < 0.05) twelve months post-treatment, except for SEA specific IgE and IgM and AWA specific IgG4 and IgM antibodies.
Conclusions: The levels of antigen-specific antibody isotypes in the sera of patients with egg positive are significantly higher than those of people with egg negative and normal control population from non-endemic area. Almost all of antibody levels decrease significantly twelve months post-treatment. The levels of antibody isotypes in the sera of people with egg negative in endemic area are significantly higher than those of population from non-endemic area, giving a clue that the selection of negative control of schistosomiasis diagnostic kit should be noticed.