Concentration of viruses from sewage by adsorption on millipore membranes.

The authors describe a relatively simple membrane-adsorption method for the efficient concentration of viruses from sewage. Sewage, first freed of bacteria by filtration through membranes under conditions that permit virus to pass freely, is then treated with anion resins to remove organic components that adsorb to Millipore membranes and prevent virus adsorption. The salt concentration of the resin filtrates is increased with MgCl(2) to enhance virus adsorption to membranes. The sewage is next adsorbed to a Millipore membrane, from which virus is readily recovered by homogenization in small fluid volumes.The method was tested in Houston, Texas, for 7 months of 1966, during which period 2795 isolates were made from 10 concentrates of 1-US-gallon (3.78-litre) samples and only 4 from unconcentrated sewage. The isolates included types 2 and 3 poliovirus, 9 echovirus types and 2 coxsackieviruses.Examination of these type 2 poliovirus strains isolated over a 4-month period showed that 13 of 19 had d(+) markers (although none was T(+)), indicating either that the vaccine strain had reverted in the d marker, or that wild strains were circulating in the population in spite of the absence of clinical disease.