Avian Influenza Virus Hemagglutinin Display on Baculovirus Envelope: Cytoplasmic Domain Affects Virus Properties and Vaccine Potential

Abstract

Hemagglutinin (HA) is the major immunogen on the envelope of avian influenza virus (AIV). Therefore we constructed two recombinant baculoviruses: Bac-HA, expressing histidine-tagged HA with the cytoplasmic domain (CTD) derived from HA, and Bac-HA64, expressing histidine-tagged HA with the CTD derived from baculovirus envelope protein gp64. After infection, HA with either CTD was expressed and anchored on the plasma membrane of Sf-9 cells, as revealed by confocal microscopy. Immunogold electron microscopy demonstrated that both Bac-HA and Bac-HA64 displayed HA on the viral surface. However, analyses of purified viruses revealed that significantly more HA was incorporated into Bac-HA64 than into Bac-HA. In comparison with Bac-HA, Bac-HA64 significantly improved the gene delivery and transgene expression in mammalian cells, as determined by quantitative real-time polymerase chain reaction and flow cytometry. Bac-HA64 elicited significantly higher hemagglutination inhibition titers in mouse models than Bac-HA and the negative controls. These data collectively confirmed that the gp64 CTD, in comparison with HA CTD, resulted in more efficient HA incorporation into baculovirus, more efficient transgene delivery and expression, and elevated immunogenicity. This is the first report demonstrating the potential of HA-pseudotyped baculovirus as an avian influenza vaccine and that the choice of CTD tremendously affects baculovirus properties and vaccine efficacy.

Innate Immune Response Induced by Baculovirus Attenuates Transgene Expression in Mammalian Cells

“…Although these characteristics might be disadvantageous for the transgene expression, the baculovirus may have potency for use as a vaccine vector possessing adjuvant activity. Recombinant baculoviruses bearing the chimeric GP64 with Plasmodium berghei circumsporozoites (58,59), Plasmodium falciparum circumsporozoites (60), Toxoplasma gondii (61), rinderpest virus (62), footand-mouth disease virus (63), pseudorabies virus (64), and avian influenza virus (65) have been shown to elicit an efficient antibody response. These results suggest that recombinant and pseudotyped baculoviruses encoding or transiently bearing foreign epitopes may induce immune responses in the antigen-presenting cells.…”

Induction of antitumor immunity against mouse carcinoma by baculovirus-infected dendritic cells

“…In particular, studies have reported the development of various antigenexpressing baculoviruses that target specific infections. [11][12][13][14][15] The recombinant baculovirus vectors strongly induced host innate and acquired immunity. We have previously reported that wild-type baculovirus induces antitumor immunity.…”

“…[7][8][9][10] In several reports, baculoviruses were developed as vaccines against pathogens. [11][12][13][14][15] Abe et al reported that baculovirus-infected host cells produced type I interferons and proinflammatory cytokines through Toll-like receptor 9 and interferon regulatory factor 7 signaling. 16,17 Schütz et al reported that baculovirus-infected, human monocyte-derived DCs expressed cell-surface activation markers and produced tumornecrosis factor alpha (TNF-a).…”

Baculovirus as a new gene delivery vector for stem cell engineering and bone tissue engineering

“…22 Another appealing application of baculovirus is in vivo gene delivery, but most previous in vivo studies delivered only reporter genes into animal models. 23 28 show that a baculovirus expressing diphtheria toxin A inhibits the glioma xenograft growth in the rat brain, suggesting the potentials of baculovirus in cancer therapy.…”