ENHANCEMENT OF BACULOVIRUS PLAQUE-ASSAY IN INSECT-CELL MONOLAYERS BY DEAE-DEXTRAN

The presence of DEAE-dextran in the agarose overlay, when titrating wi ld-type or recombinant baculoviruses by plaque assay, resulted in a hi gher definition and contrast of viral plaques and increased the plaque number and mean diameter at least by a factor of 2x on day 5 post inf ection. This increase was related to neither a larger production of in fectious virus nor of recombinant protein and did not occur when the p olycation was only present in the virus inoculum or when insect cell m onolayers were preincubated for 60 min with it. The extension of the o bservations to a number of different recombinant viruses from varied s ources, including several baculoviruses that could not consistently pr oduce plaques in the absence of the polycation, substantiates the use of DEAE-dextran to perform a more reliable, faster and reproducible pl aque assay of recombinant baculoviruses.