Enhancement by diethylamineothyl-dextran of the plaque-forming activity of foot-and-mouth disease virus-antibody complexes in pig kidney IB-RS-2 cells.

Mixtures of foot-and-mouth disease (FMD) virus and homologous antibody, assayed for surviving plaque-forming units (PFU) in pig kidney IB-RS-2 cells, demonstrated an average ten-fold greater recovery of infectivity when diethylaminoethyl-dextran (DEAE-dextran) was included in the overlay medium. This enhancement, which was not detected in baby hamster kidney BHK21 cells, was due to the ability of the polycation to potentiate attachment of virus-antibody complexes to the IB-RS-2 cells. In some instances the effect was so pronounced that the plaque-forming activity of virus in the presence of homologous antibody exceeded that of virus alone.