Dot blot hybridization assay of B19 virus DNA in clinical specimens

A nonradioactive dot blot hybridization assay for human parvovirus B19 DNA was set up by using a biotin-labeled DNA probe and streptavidin-alkaline phosphatase conjugate. The assay was used to examine 4,895 specimens referred for B19 virus diagnosis during 1987. Of 48 specimens that gave positive reactions for B19 DNA, 41 were confirmed virus positive by electron microscopy (n = 36), radioimmunoassay (n = 26), or counterimmunoelectrophoresis (n = 20). In 7 samples which were not confirmed and in 11 samples giving weak reactions for B19 DNA, there was serological or epidemiological evidence of recent B19 infection. A further 70 specimens gave weak, apparently false-positive reactions. By electron microscopy, 13 of 16 were contaminated by bacteria, and plasmid DNA was demonstrated in one specimen. Of 55 specimens tested, 52 reacted with streptavidin-alkaline phosphatase conjugate alone. These were probable sources of nonspecificity in an otherwise practical and economic screening method for B19 virus.