In vitro culture for the detection of infectious human parvovirus B19 and B19-specific antibodies using foetal haematopoietic precursor cells

1 University of Oxford, Nuffield Department of Pathology and Bacteriology, John Radcliffe Hospital, Oxford OX3 9DU and 2 University College and Middlesex Hospital School of Medicine, Department of Medical Microbiology, Division of Virology, London, U.K. The inability to culture human parvovirus B19 in standard cell lines has rendered investigation of clinical samples for the presence of infectious virus problematic. Using haematopoietic precursors derived from first trimester foetal liver as targets for infection, and non-isotopic in situ hybridization to detect intracellular virual DNA, we have assessed infectivity in stored serum samples taken from nine volunteers at different stages following intranasal inoculation with parvovirus B19. Infectious virus was detected as early as 3 days after inoculation, the cessation of infectivity correlating with the rise in specific IgM. In all but two samples, infectivity correlated with the detection of B19 DNA by dot-blot hybridization, although in vitro culture was 10-fold more sensitive than dot-blot hybridization. B19 DNA was detected by the polymerase chain reaction in serum from one volunteer up to 36 days after inoculation, although samples containing specific antibody were non-infectious. Infection of erythroid precursors was completely inhibited by preincubation of virus with serum containing high titre B19-specific IgM and IgG. Unexpectedly, this was associated with a strong B19 DNA hybridization signal within the cytoplasm of phagocytic macrophages. This culture and detection system is a rapid and sensitive means of detecting infectious virus in serum samples, and of assessing the neutralizing ability of B19-specific antibodies. Present address: Clinical Research and Development, British Biotechnology Ltd, 4–10 The Quadrant, Abingdon, Oxfordshire, U.K. > Present address: Department of Microbiology, Leicester University, Leicester, U.K. Received 3 August 1992; accepted 25 August 1992.