An application of factor analytics on antigenic drift, and chromatographic analysis on intratypic variation of enterovirus type 70.

An attempt was made to reveal the antigenic determinant site of enterovirus (EV) 70 by application of Harman's factor analytics. The normalized neutralization rate constant (NK) values obtained by the kinetic-neutralization tests (NT) with 12 strains of EV70 isolated during the period from 1971 to 1976 were used in the principal factor analysis. From the analytic results, it was suggested that at least two antigenic determinant sites, composing to variable antigenic factor (VAF) and common one (CAF), might be closely related to the antigenic makeup. There were no significant differences in CAF score among the strains, and they were numerically classified into prototype-like and prime-like virus groups from the VAF scores. The drift appeared here could be explained as successive alteration of VAF scores. Chromatographic analyses were carried out on intratypic variable and common particles with two virus strains, i.e. the prototype J 670/71 and prime G-2/74. The intratypic variable and common particles were eluted in low and high ionic concentrations at neutral pH, respectively. It was concluded that the virus populations of two strains were heterogenic in the proportion of variable to common virus particles.