Studies on neutralization of Japanese encephalitis virus. IV. Effect of anti-cellular serum on the neutralization of sensitized virus by anti-rabbit IgG serum.

The effect of anti-cellular rabbit serum (ACRS) on the neutralization of sensitized Japanese encephalitis virus (JEV) by anti-rabbit IgG serum was examined to elucidate the interaction between virus-antibody complex and the surface of the host cells during the process of neutralization. ACRS had no effect on the adsorption of either sensitized or non-sensitized virus, but was able to restore the lost infectivity of sensitized virus which occurred during the process of neutralization by anti-rabbit IgG serum. This restoration of infectivity was found to take place not only by the addition of ACRS to the reaction mixtures (virus-antibody, anti-rabbit IgG complex) but also by pretreatment of the host cells with ACRS. Although the restoration of lost infectivity varied in magnitude with the concentration of ACRS used, it never exceeded the infectivity titer of the sensitized virus befor incubatio with anti-rabbit IgG serum. This result suggests that ACRS has no ability to reverse the neutralization by anti-viral serum. Since the ACRS reacted only with anti-rabbit IgG serum treated sensitized virus, resulting in an increase of the number of infectious centers, the restoration of lost infectivity was explained as being due to the enhancement of adsorption of sensitized virus to the host cells by bridge formation of anti-rabbit IgG antibody between them.