Use of non-neutralizing monoclonal antibodies in an ELISA for intratypic differentiation of 28 echovirus type 25 clinical isolates.

Three non-neutralizing monoclonal antibodies were produced and selected against echovirus type 25 JV-4 prototype strain. They were used in an ELISA to investigate the intratypic differentiation of 28 wild isolates. Clinical isolates fell into seven different groups according to their reactivity patterns in ELISA. Two of the non-neutralizing monoclonal antibodies, 9E4 and 6D3, were highly specific, while the third, 6C9, may recognize an epitope common to other types of echoviruses. In contrast, mouse polyclonal antiserum exhibited large cross-reactivities among echovirus serotypes. The reactivity patterns and the geographical origin of the isolates were generally not correlated and, in the same area, four major antigenic variants sometimes coexisted, especially in the south of France. Moreover, reactivity patterns found with ELISA were hardly ever correlated with those observed in a previous study when neutralization tests were used. These results again underline the non-correlation between structure and biological function in the Picornavirus family.