Specific IgG4 response directed against the 45-kDa glycoprotein in trichinellosis: a re-evaluation of patients 15 years after infection.

The aim of this study was to evaluate the humoral immune response in late human trichinellosis with particular attention to the presence of IgG4 antibodies directed against the Trichinella-45-kDa glycoprotein (gp). This study re-evaluates subjects 15 years after they were involved in a trichinellosis outbreak that occurred in Central Italy following the consumption of raw boar meat infected with Trichinella britovi. The results show that ELISA tests using the E/S antigen identified five IgM- and eight IgG-positive patients and no IgA-positive patients. Tests using immunoblot (IB) with E/S antigens identified three IgM-, five IgA-, seven- IgG1- and three IgG4-positive sera. When the purified 45-kDa gp was used as an antigen, the IB revealed that six of the ten sera tested were positive for IgG4. Sera were also evaluated with a commercial kit, revealing that 11 of 12 patients had a highly sensitive reactivity against Trichinella proteins (64 and 44-43 kDa). In conclusion, humoral immune response against Trichinella is still present in these patients 15 years after the initial infection, including an IgG4 response directed to the 45-kDa gp.