Characterization of the Antibody Response in Vaccinated Mice Protected Against Coxsackievirus B3-Induced Myocarditis

Adolescent male CD-1 mice can be rendered resistant to coxsackievirus B3 (CVB3 m )-induced myocarditis following inoculation as neonates with a single dose of a temperature-sensitive mutant virus (ts1), derived from the prototype parent virus (CVB3 m ). Previously, anti-CVB3 m neutralizing antibodies were not detected in sera of adolescent ts1 vaccinees by a standard plaque-reduction assay (Gauntt et al 1983. Infect. Immun. 39 :851). However, a more sensitive cytopathic effects-reduction assay permitted detection of low titers of anti-CVB3 m neutralizing antibodies of the IgG class prior to challenge with CVB3 m . Following CVB3 m challenge, serum anti-CVB3 m neutralizing antibody titers of tsl vaccinees declined on days 1-2 post-inoculation (p.i.) then increased over the next 6 days. The neutralizing antibodies were of both the IgG and IgM classes. Normal mice challenged with CVB3 m did not produce detectable serum anti-CVB3 m neutralizing antibody until day 4 p.i. and by 8 days p.i. the neutralizing antibody was only of the IgM class. Thus, adolescent murine ts1 vaccinees mount a secondary antibody response to CVB3 m in both neutralizing IgG and IgM, but resistance to CVB3 m -induced myocarditis is due to the presence of low levels of anti-CVB3 m IgG neutralizing antibody in serum at the time of challenge with CVB3 m .