Virus passage through track-etch membranes modified by salinity and a nonionic surfactant.

Why do viruses sometimes not pass through larger pores in track-etch filters? Increasing the salinity (0.8 to 160 mM Na+) decreased phiX174 and PRD1 passage through track-etch polycarbonate membranes (sodium dodecyl sulfate coated but not polyvinylpyrrolidone coated) and PRD1 passage through polyester membranes. Undiminished passage when 0.1% Tween 80 was added implied that nonionic virus adsorption occurred and indicated that high levels of salinity decreased virus passage by decreasing electrostatic repulsion that prevented adsorption.