A simple planimetric method to quantify cytotoxicity in cell culture monolayers.

Planimetry was shown to be a rapid, simple and reproducible method to quantify gross cytotoxicity in cell culture monolayers. A shellfish extract prepared from blue mussels (Mytilus edulis) was cytotoxic to Buffalo green monkey kidney cells. Exposure of cells to mussel extracts for 1, 2 and greater than or equal to 4 h followed by agar (plaque assay) overlays produced 34, 87, and 100% destruction of the monolayers, respectively, within 72 h. Planigraphs, prepared from tracing areas of cytotoxicity onto sheets of paper, served as permanent records of toxicity which were easily measured by planimeter experienced and nonexperienced scientists. Planimetric procedures may have utility in measuring biological and chemical toxicity as well as physiological stress in cell monolayers.

A method for the enumeration of poliovirus in selected molluscan shellfish.

A virus extraction procedure was developed and evaluated on five commercially important molluscan shellfish species: Crassostrea virginica (Eastern oyster), Mya arenaria (softshell clam), Mytilus edulis (blue mussel), Mercenaria mercenaria (hardshell clam), and Crassostrea gigas, (Pacific oyster). Shellfish tissue homogenates were spiked with poliovirus, extracted, and plaque assayed. Mean virus recoveries were: C. virginica, 63.8%; M. arenaria, 42.1%; M. edulis, 67.3%; M. mercenaria, 48.3%; and C. gigas 10.1%. Shellfish were also allowed to accumulate poliovirus from spiked seawater (10 to 20 PFU/ml of water) over 48 to 72 h. The results indicate that poliovirus could be extracted from four shellfish species exposed to near environmental levels of virus. Virus recoveries per gram of tissue were: M. arenaria, 11.7 PFU; M. mercenaria, 26.0 PFU; M. edulis, 21.5 PFU; and C. virginica, 2.0 PFU. The results of this study indicate that the procedure is effective in extracting ingested viruses from several shellfish species. This procedure may have practical application for enumeration of enteric viruses in environmental samples.