Type-specific and cross-reactive antigenicity of capsid proteins VP1 and VP2 of echovirus type 7

Isolation and preliminary characterization of antigenic variant of echovirus type 11

Nosocomial infection with echovirus type 11 resulting in aseptic meningitis occurred among newborn babies in a hospital neonatal room at Fukui city. The virus was identified as a variant of echovirus type 11 by cross-neutralization tests with antisera against the prototype Gregory strain and the current Fukui isolate. Fukui isolates expressed strain specific antigen(s) in addition to type specific common antigen(s), but lacked a certain antigen(s) which was present in the prototype strain. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of virus polypeptides revealed that the capsid proteins VP2 and VP3 of Fukui strain migrated more rapidly than the Gregory strain, while both strains had the same migration pattern of VP1 protein on which the antigenic determinants responsible for virus neutralization were present. The current strain produced large plaques and was more thermoresistant, suggesting some alterations in the structural proteins of the virus.

Characterization of an echovirus type 30 variant isolated from patients with aseptic meningitis

An outbreak of echovirus type 30 infection associated with aseptic meningitis occurred among newborn babies in a hospital neonatal room at Fukui City in 1983. The isolated virus was identified as an antigenic variant of echovirus type 30 by cross-neutralization tests with antisera against the prototype Bastianni strain and the present isolate. Western blot analysis demonstrated that the antigenic determinants responsible for virus neutralization, some of which were type specific and others strain specific, were present on the capsid protein VP1. The current strain was more thermoresistant than the prototype, suggesting some alterations in virus structural proteins.

Cross-reactions of immunoglobulin M and G antibodies with enterovirus-specific viral structural proteins

We analysed the reactivity of enterovirus-specific human IgM and IgG antibodies with the structural proteins of different enteroviruses by the immunoblot technique. In general, all immunoglobulin G antibodies of the tested sera reacted with capsid polypeptide VP 1 of the viruses tested (echoviruses 9 and 11, coxsackievirus B3 and poliovirus 2). In contrast, enterovirus specific immunoglobulin M antibodies of adults reacted with capsid polypeptides VP 1, VP 2, and/or VP 3 of the viruses mentioned above. The reactions with VP 2 and/or VP 3 were often stronger than with VP 1. IgM antibodies from sera of newborns infected by echovirus 11 reacted with VP 1 and VP 2/3 of echovirus 11 and also with VP 2 and VP 3 of poliovirus 2. Preabsorption experiments indicate that cross-reactive IgG antibodies react with epitopes of VP 1 not present on the surface of intact virus particles. The results from the immunoblot technique were compared to data from microneutralization tests and M-antibody capture radioimmunoassays.