Parvovirus B19 (B19V) is a human ssDNA virus responsible for a wide range of clinical manifestations, still lacking for a specific
antiviral therapy. The identification of compounds active against B19V may add therapeutic options to the treatment of B19V
infections, that now entirely relies on symptomatic treatments. In the search for compounds possibly inhibiting B19V replication, a particular focus was raised to
cidofovir, an acyclic
nucleoside phosphonate broadly active against dsDNA viruses. The present study was aimed at evaluating the effect of
cidofovir against B19V in two model systems, the UT7/EpoS1 cell line and erythroid progenitor cells (
EPC), generated from peripheral blood mononuclear cells. Experiments were carried out at different multiplicity of
infections and
cidofovir concentrations (0-500 μM) during a course of
infection. The effects of
cidofovir on B19V replication were assessed by qPCR assays while influence of
cidofovir on host cells was measured by cell proliferation and viability assays. Our findings demonstrated that
cidofovir has a relevant inhibiting activity on B19V replication within infected UT7/EpoS1, and that the effect on B19V
DNA amounts is dose-dependent allowing for the determination of EC50 and EC90 values (7.45-41.27 μM, and 84.73-360.7 μM, respectively). In EPCs, that constitute a cellular population close to the natural target cells in bone marrow, the inhibitory effect was demonstrated to a lesser extent, however provoking a significant reduction on B19V
DNA amounts at 500 μM (68.2-92.8%). To test infectivity of virus released from EPCs cultured in the presence of
cidofovir, cell culture supernatants were used as inoculum for a further course of
infection in UT7/EpoS1 cells, indicating a significant reduction in viral infectivity at 500 μM
cidofovir. Since the
drug did not interfere with the overall cellular
DNA synthesis and metabolic activity, the observed effect of
cidofovir could be likely related to a specific inhibition of B19V replication.