Evaluation of a Method for Recovering Poliovirus 1 from 100-Gram Oyster Samples

A method is described that uses commonly available laboratory equipment and materials to detect low numbers of poliovirus 1 in oysters. Thirty 100-g oyster samples inoculated with poliovirus 1 were processed by blending at pH 4.8 in water, centrifuging, extracting the pellet at pH 9 in a mixture of Eagle's medium, nonfat dry milk, MgCl₂·6H₂O, and Freon TF, and centrifuging again. The supernatant fluids were diluted in water, precipitated at pH 4.8 and centrifuged. The pellets were resuspended in Na₂HPO₄ and Cat-Floc, and centrifuged. The final supernatant fluids (~10 ml per sample) were assayed for viral plaque-forming units (PFU) in BGM African monkey green kidney cell monolayers. The average inoculum per sample was 95 PFU, and the average recovery from 30 samples was 53 PFU. The percent recovery with 95 percent confidence intervals was 55.4 ± 2.1.