Inclusion of the central exon of parvovirus B19 precursor mRNA is determined by multiple splicing enhancers in both the exon and the downstream intron

Alternative splicing of the precursor mRNA (pre-mRNA) of human parvovirus B19 (B19V) plays a key role in posttranscriptional regulation of B19V gene expression. We report that the central exon of the B19V pre-mRNA is defined by three GAA motif-containing exonic splicing enhancers and a G/GU-rich intronic splicing enhancer that lies adjacent to the second donor site. Moreover, targeting of morpholino antisense oligonucleotides to the two splicing enhancers surrounding the second donor site led to a significant reduction in splicing at this donor site during B19V infection of permissive CD36⁺ erythroid progenitor cells.