FIG. 6.

Western blot analysis of serum and fecal supernatants from C57BL/6 (wild-type [WT]) and IgA^−/− mice collected 21 days after oral reovirus inoculation. Serum and fecal supernatants of two representative mice from each group are shown. Lanes 1 and 2, sera from naive control mice showed no anti-ς1 immunoreactivity although nonspecific binding of IgG to other reovirus proteins was seen. Lanes 3 and 4, anti-ς1 IgG antibodies were consistently present in the sera of reovirus-exposed WT mice. IgG binding to other proteins was variable. Lanes 5 and 6, sera from naive IgA^−/− mice showed some nonspecific IgG binding to some reovirus proteins but not to ς1. Lanes 7 and 8, sera from IgA^−/− mice orally inoculated with reovirus contained anti-ς1 IgG antibodies. Lanes 9 and 10, fecal supernatants of naive control WT mice did not contain detectable anti-ς1 IgA antibodies, although nonspecific IgA binding to other reovirus proteins was observed. Lanes 11 and 12, anti-ς1 IgA antibodies were detected in fecal supernatants of reovirus-exposed WT mice. Lanes 13 to 16, no reovirus-specific or nonspecific IgA was detected in fecal supernatants of naive or reovirus-exposed IgA^−/− mice. Lanes 17 and 18, control strips exposed to secondary goat anti-mouse IgG and to IgA, respectively.