Baculovirus Display of Peptides and Proteins for Medical Applications

Abstract

Baculoviridae is a large family of arthropod-infective viruses. Recombinant baculoviruses have many applications, the best known is as a system for large scale protein production in combination with insect cell cultures. More recently recombinant baculoviruses have been utilized for the display of proteins of interest with applications in medicine. In the present review we analyze the different strategies for the display of proteins and peptides on the surface of recombinant baculoviruses and provide some examples of the different proteins displayed. We analyze briefly the commercially available systems for recombinant baculovirus production and display and discuss the future of this emerging and powerful technology.

Keywords: GP64; VP39; baculovirus display; vaccines.

Figure 1

Protein display strategies in the “Baculovirus display” system. (A) Envelope display of full-length proteins, domains, or peptides fused to the full length GP64 protein or fragments as the signal peptide (SP) and transmembrane domain (TM) (1). Baculoviruses in which GP64 has been deleted (ΔGP64) have been shown to be functional when GP64 is expressed as a recombinant protein fused to a gene of interest (GOI). (2 and 3) Other strategies consist in display proteins associated with transmembrane domains of non-baculovirus proteins, or those that have their own transmembrane domain. (B) Display of capsid proteins, fused to the amino or carboxyl terminus of the VP39 capsid protein.

Figure 2

Functional display of the nonapeptide bradykinini on the surface of recombinant baculoviruses. (A) cartoon displaying the constructs for the expression of a second copy of recombinant GP64 (Bac-GFP and Bac-Bk) under the polyhedrin promoter. (B) Sf9 insect cells expressing the human type 2 bradykinin (B2) receptor (produced with a recombinant baculovirus carrying the cDNA for human B2) were stimulated by the addition of commercially available bradykinin (Bk, Sigma). FURA-2 loaded cells responded to Bk with a rapid elevation in intracellular calcium (red line). (C) insect cells expressing B2 were exposed to the Bac-Bk virus displaying the nonapeptide bradykinin on its surface fused to GP64. Cells responded with a slower elevation in intracellular calcium (green line). Cells stimulated with the recombinant baculovirus expressing GFP fused to GP64 did not respond to the stimulation, indicating that the response to Bac-Bk was due to bradykinin (blue line). (D) bradykinin stimulation of cells expressing the human B2 receptor was completely blocked with the potent antagonist HOE-140 (red line). (E) similarly, the calcium response induced by Bac-Bk was blocked by the same antagonist (red line). All data presented are the mean +- standard deviation obtained from at least 10 independent measurements from 5 different infections. (F) typical dose-response curve to bradykinin in cells expressing the human B2 receptor. (G) a dose-response curve was also obtained using different dilutions of the Bac-Bk recombinant virus. Data points represent the mean +- standard deviation obtained from at least 10 independent measurements from 5 different infections. For these experiments recombinant baculoviruses were purified by ultracentrifugation.