ENZYMATIC AMPLIFICATION OF LACTATE DEHYDROGENASE-ELEVATING VIRUS

To improve the detection of lactate dehydrogenase-elevating virus (LDV ), we developed a PCR assay. Primers were selected from ORF7, encoding nucleocapsid protein VP1. No specific amplification was observed with any other common murine virus or with RNAs from the closely related L elystad virus and equine arteritis virus. In experimentally infected m ice, LDV could be detected in plasma in both the acute and the persist ent phases. LDV was also detected by the PCR in contaminated pools of Plasmodium berghei parasites which were maintained in mice, both by a direct analysis of the samples and by testing of plasma from mice inoc ulated with these pools. There was a complete agreement between the re sults of the PCR assay and the lactate dehydrogenase (LDH) enzyme assa y of plasma from the inoculated mice. In contrast to the results of th e LDH enzyme assay, no false-positive reactions were obtained in the P CR assay with negative control samples showing visible hemolysis. Stor age of plasma samples at room temperature and at 4, -20, and -80 degre es C for up to 8 days did not influence the results of the PCR. These results show that the PCR is a valuable technique which may replace th e LDH test as a diagnostic tool.