CONCENTRATION OF HEPATITIS A VIRUS IN ENVIRONMENTAL-SAMPLES

The cytopathogenic pHM-175 strain of hepatitis A virus was used to develop different procedures for the concentration of HAV in tap water, fresh water, seawater and raw sewage. HAV was quantified by a plaque assay in the FRhK-4 cell line. Water samples were concentrated by a modification of the adsorption to and elution from glass powder (GPAE) method, by adsorption to and elution from filter aid, and by ammonium sulfate flocculation (ASF). The GPAE method consistently yielded greater HAV recoveries than filtration through filter aid, or ASF. HAV was concentrated by GPAE from 20-litre samples with satisfactory efficiencies in all kinds of water: 100% for tap water, 80% for freshwater, 75% for seawater and 61% for sewage. Concentration efficiencies for filter aid and ASF were always lower than 25% and 40%, respectively, in any kind of water. The charge of glass powder was modified by polyethylenimine treatment. Concentration efficiencies of HAV in 20 1 samples through adsorption to and elution from positively charged glass powder (PGPAE) were 100% for tap water, 94% for seawater, and 61% for freshwater and sewage. The presence of wild-type HAV in sewage samples could be monitored by molecular hybridization with cDNA probes after GPAE concentration.