Construction and sequencing of an infectious clone of the human parvovirus B19.

Human parvovirus B19 has a nonenveloped, icosahedral capsid packaging a linear single-stranded DNA genome of 5.6 kb with long inverted terminal repeats (ITR) at both the 5' and 3' end. Previous attempts to construct a full-length B19 clone were unsuccessful due to deletions in the ITR sequences. We cloned the complete parvovirus B19 genome with intact ITRs from an aplastic crisis patient. Sequence analysis of the complete viral genome indicated that both 5' and 3' ITRs have two sequence configurations and several base changes within the ITRs compared to previous published sequences. After transfection of the plasmid into permissive cells, spliced and non-spliced viral transcripts and viral capsid proteins could be detected. Southern blot analysis of the DNA purified from the plasmid-transfected cells confirmed parvovirus B19 DNA replication. Production of infectious virus by the B19 plasmid was shown by inoculation of cell lysate derived from transfected cells into fresh cells. Together, these results indicate the first successful production of an infectious clone for parvovirus B19 virus.