VALIDITY OF SEROLOGICAL METHODS (ELISA) FOR DETECTING INFECTIOUS VIRUSES IN WATER

Detection of cultivable enteric viruses in environmental water samples in tissue culture is time consuming and expensive. Moreover, some imp ortant enteric viruses grow very slowly (Hepatitis A virus) or do not grow as yet (Norwalk) in tissue culture. Therefore, sensitive serologi cal and molecular methods have been developed to simplify and speed th e detection of viruses in environmental samples. This study was conduc ted-to test the reliability of serological methods to monitor the pres ence of viable viruses in natural waters. The study was performed with poliovirus purified in cscl gradients and impure virus. Poliovirus 1 either purified or impure was seeded in raw wastewater, groundwater an d phosphate buffered saline (PBS) and incubated for 20 days at 4 degre es C, 20 degrees C and 30 degrees C. Virus survival was monitored by a nylon filter A-ELISA and plaque-assay in BGM cells. In all water samp les at 4 degrees C, no die-off was observed neither by A-ELISA nor pla que-assay. In wastewater and groundwater at 20 degrees C and 30 degree s C, greater die-off was observed with A-ELISA than with plaque-assay. Purified poliovirus was undetectable by the A-ELISA after two days of incubation at 20 degrees C in wastewater and groundwater, whereas und er the same conditions, only 2log(10) reduction were observed in the t iter of poliovirus 1. The data of this study have shown that in all ca ses, a positive test by A-ELISA was also positive by the plaque-assay. Therefore, a positive result of A-ELISA indicates the presence of via ble virus in natural waters.