Presence of an anti-viral factor in peritoneal dialysis effluent

Viral peritonitis is an exceptionally rare occurrence in peritoneal dialysis. In fact, up to now, only one case report has been documented in the literature. In a prospective study, peritoneal dialysis effluent (PDE) was specifically cultured for the following viruses: the herpes group of viruses, including herpes simplex types I (HSV) and II, cytomegalovirus (CMV) and varicella-zoster (V-Z), and the enteroviruses group including coxsackie B-5 (Cox B), echo, enterovirus and polio. Cultures were performed under both basal conditions and in the presence of peritonitis. No viral growth was demonstrated. The possible existence of an anti-viral factor in the PDE was therefore raised. In order to investigate this hypothesis, the PDE of 16 patients undergoing intermittent peritoneal dialysis and of 24 patients on continuous ambulatory peritoneal dialysis were examined for anti-viral activity. The method used was analogous to that employed for testing the anti-viral effect of interferon (IFN). The inhibition of the cytopathic effect (CPE) of various viruses was examined in the following tissue cultures: Vero cells (a line of monkey kidney cells) incubated with HSV, vesicular stomatitis virus (VSV) and Cox B; human kidney cells incubated with parainfluenza 3 (Para-3); human foreskin fibroblasts incubated with CMV, HSV and VSV and L-929 (a line of mouse cells) incubated with VSV. As control, unused Dianeal (Travenol, Ashod, Israel) 1.5 and 4.25 g/dl, normal saline and 5 g/dl dextrose solutions were tested under the same conditions using VSV on Vero. The PDE was also examined for the presence of specific anti-viral antibodies by microneutralization and ELISA tests. The presence of human IFN (β and γ) was evaluated by radioimmunoassay using anti IFN monoclonal antibodies. Human IFN α was tested by a bioassay using MBDK cells with VSV. PDE from both patients on intermittent peritoneal dialysis and continuous ambulatory peritoneal dialysis inhibited the cytopathic activity of all the viruses tested in the various tissue cultures, except for the mouse line of cells. No such inhibition was seen with the control solutions. Only antibodies to HSV were detected in the PDE and their titer did not correlate with the inhibition of cytopathic effect. Human IFN α, β and γ were not detected. These studies suggest that PDE contains an anti-viral factor which is not a known IFN or an anti-viral antibody. This factor is active against both RNA and DNA viruses in both human and monkey cell cultures.