Conventional and enhanced plaque neutralization assay for polio antibody.

HEp-2 cells were more suitable as a cell substrate than Vero cells for plaque assay of wild or attenuated strains of poliovirus. Polio antibody titration by plaque neutralization was on the average 3.4 to 4.8 times more sensitive than antibody titration by virus CPE assay. The most pronounced effect on virus neutralization was achieved by extending the time of serum-virus interaction. Incubating the virus-antiserum mixture for 20 h instead of 1 h at 36 degrees C increased antibody titer to all three poliovirus types about 11- to 28-fold. Potentiation of poliovirus neutralization by heterologous antiglobulin was considerably less effective than with other virus-antibody systems. The virus plaque neutralization technique described should be capable of measuring minute amounts of antibody as required in special circumstances.