Codon optimization of human parvovirus B19 capsid genes greatly increases their expression in nonpermissive cells.

Parvovirus B19 (B19V) is pathogenic for humans and has an extreme tropism for human erythroid progenitors. We report cell type-specific expression of the B19V capsid genes (VP1 and VP2) and greatly increased B19V capsid protein production in nonpermissive cells by codon optimization. Codon usage limitation, rather than promoter type and the 3' untranslated region of the capsid genes, appears to be a key factor in capsid protein production in nonpermissive cells. Moreover, B19 virus-like particles were successfully generated in nonpermissive cells by transient transfection of a plasmid carrying both codon-optimized VP1 and VP2 genes.