The effect on recombinant protein production of reinstating native introns in the coding sequence of human factor VIII

Reinstating two naturally occurring intervening sequences of the human factor VIII gene into a B domain-deleted factor VIII cDNA sequence, either as separate entities or in combination, revealed slightly elevated protein production in the case of intron 8, while the addition of intron 16 markedly reduced protein levels. This reduction may be due to decreased levels of mRNA.