Secretion of glycosylated human recombinant haptoglobin in Baculovirus-infected insect cells

Abstract

Human haptoglobin (Hpα²β) was synthesized in insect cells using the baculovirusAutographa california nuclear polyhedrosis virus (AcNPV) as an expression vector. Viruses carrying the proHpα²β cDNA, either fused or non fused to viral polyhedrin DNA sequences, expressed intracellularly low levels of unglycosylated and non maturated haptoglobin. On the contrary, recombinant viruses containing the preoroHpα²β cDNA directed the expression of high levels of prohaptoglobin. To a large extent, the uncleaved product was found in the culture medium as a glycosylated molecule. Despite the lack of maturation into subunits, the secreted recombinant prohaptoglobin was able to bind hemoglobin in vitro, although less efficiently than plasma-derived haptoglobin.