Detection of antibody responses
Antigen-specific IgG, IgG1, IgG2a, IgE, and IgA antibodies in the sera
were detected by indirect ELISA as previously described
(Huber et al., 2006). The absorbance was
measured with an ELISA reader at 490 nm. The data are expressed as the
mean absorbance of the samples minus the mean absorbance of the normal
control.