Quantitative method of measuring anti-viral activity of peritoneal dialysis effluent

We have previously documented the presence of anti-viral activity in the peritoneal effluent of uremic patients treated by peritoneal dialysis. Anti-viral activity was determined by recording the inhibition of the cytopathic effect (CPE) of various viruses on Vero cells in a semi-quantitative manner based on observer's subjective judgment of the degree of inhibition of CPE. This degree of inhibition is a measure of the anti-viral activity. Although peritoneal dialysis effluent (PDE) was consistently seen to inhibit CPE we sought a quantitative method to accurately assess such anti-viral activity. To this end, the CPE of Parainfluenza virus (Para-3) on human kidney (Hu-K) cells was evaluated. The CPE of this virus is manifested by distinct plaques which can be easily counted after staining the tissue culture plate. Eighty-three (83) samples of PDE (0.5 ml) were added to Hu-K cells after which Para-3 was added. As control para-3 on Hu-K was used. The number of plaques obtained by virus control was taken as 100% CPE. The anti-viral activity of PDE was then recorded as the percentage of the CPE shown by virus control and averaged 20.9 +/- 28.6% (p less than 0.001 vs virus control). In addition PDE was diluted down to 1/64 concentration and the inhibitory effect again determined. Percent CPE of undiluted, 1/2, 1/64 PDE samples were 18.11 +/- 24.2, 33.57 +/- 18.16 and 77.93 +/- 17.4% respectively (p less than 0.01 between undiluted and 1/64 PDE). These data reaffirm that PDE possesses an inherent anti-viral activity which can now be quantitatively assessed using Para-3 on Hu-K cells.(ABSTRACT TRUNCATED AT 250 WORDS)