HIV-1 Virus-Like Particles Produced by Stably Transfected Drosophila S2 Cells: a Desirable Vaccine Component

Abstract

The development of a successful vaccine against human immunodeficiency virus type 1 (HIV-1) likely requires immunogens that elicit both broadly neutralizing antibodies against envelope spikes and T cell responses that recognize multiple viral proteins. HIV-1 virus-like particles (VLP), because they display authentic envelope spikes on the particle surface, may be developed into such immunogens. However, in one way or the other current systems for HIV-1 VLP production have many limitations. To overcome these, in the present study we developed a novel strategy to produce HIV-1 VLP using stably transfected Drosophila S2 cells. We cotransfected S2 cells with plasmids encoding HIV-1 envelope, Gag, and Rev proteins and a selection marker. After stably transfected S2 clones were established, HIV-1 VLP and their immunogenicity in mice were carefully evaluated. Here, we report that HIV-1 envelope proteins are properly cleaved, glycosylated, and incorporated into VLP with Gag. The amount of VLP released into culture supernatants is comparable to those produced by insect cells infected with recombinant baculoviruses. Moreover, cryo-electron microscopy tomography revealed average 17 spikes per purified VLP, and antigenic epitopes on the spikes were recognized by the broadly neutralizing antibodies 2G12, b12, VRC01, and 4E10 but not by PG16. Finally, mice primed with DNA and boosted with VLP in the presence of CpG exhibited anti-envelope antibody responses, including ELISAbinding, neutralizing, antibody-dependent cell-mediated cytotoxicity and antibody-dependent cell-mediated viral inhibition, as well as envelope and Gag-specific CD8 T cell responses. Thus, we conclude that HIV-1 VLP produced by the S2 expression system has many desirable features to be developed into a vaccine component against HIV-1.

Multi-parameter exploration of HIV-1 virus-like particles as neutralizing antibody immunogens in guinea pigs, rabbits and macaques

“…Considering that all currently licensed vaccines against infectious diseases and several others under development are particle-based, many of which incorporate lipid membranes, this general approach has a strong track record (Garrone et al, 2011; Kanekiyo et al, 2013; Kulkarni et al, 2012; Kushnir et al, 2012; Roldao et al, 2010). Particle vaccines presenting native HIV-1 Env spikes have so far been explored in the form of live inactivated viruses, VLPs, liposomes and virosomes (Bomsel et al, 2011; Buonaguro et al, 2005; Chen et al, 2005; Crooks et al, 2007; Dennison et al, 2011; Doan et al, 2005; Evans et al, 2005; Grovit-Ferbas et al, 2000; Grundner et al, 2002; Hammonds et al, 2003; Hammonds et al, 2005; Hammonds et al, 2007; Hicar et al, 2010; Kamdem Toukam et al, 2012; Lifson et al, 2004; McBurney et al, 2007; McKenna et al, 2004; McKenna et al, 2003; Montero et al, 2012; Pastori et al, 2012; Poon et al, 2005; Visciano et al, 2011; Vzorov et al, 1999; Yang et al, 2012; Zhou et al, 2011). However, none have yet demonstrated a great potential to elicit tier 2 nAbs.…”

Altered Glycosylation Patterns Increase Immunogenicity of a Subunit Hepatitis C Virus Vaccine, Inducing Neutralizing Antibodies Which Confer Protection in Mice

“…To directly determine the contribution of glycosylation to the induction of bNAbs by sE2, we produced sE2 in mammalian and insect cell lines known to yield altered glycan structures on proteins (42). To produce the E2 protein of the HCV strain Con1 (genotype 1b) in insect cells, we used an established Drosophila S2 cell expression system (43). Transgenic cell lines expressing sE2 comprised of residues 384 to 661 were recovered following transfection of Drosophila S2 cells with pMT-sE2 and subsequent antibiotic selection (Fig.…”

Virus-mimetic nanovesicles as a versatile antigen-delivery system

“…3 A, i), and then the MCVs were purified by sequential density sucrose gradient ultracentrifugation (20). To prepare VMVs displaying sig-16L2-eGFP (Fig.…”