The porcine circovirus type 1 capsid gene promoter improves antigen expression and immunogenicity in a HIV-1 plasmid vaccine

Abstract

BackgroundOne of the promising avenues for development of vaccines against Human immunodeficiency virus type 1 (HIV-1) and other human pathogens is the use of plasmid-based DNA vaccines. However, relatively large doses of plasmid must be injected for a relatively weak response. We investigated whether genome elements from Porcine circovirus type 1 (PCV-1), an apathogenic small ssDNA-containing virus, had useful expression-enhancing properties that could allow dose-sparing in a plasmid vaccine.ResultsThe linearised PCV-1 genome inserted 5' of the CMV promoter in the well-characterised HIV-1 plasmid vaccine pTHgrttnC increased expression of the polyantigen up to 2-fold, and elicited 3-fold higher CTL responses in mice at 10-fold lower doses than unmodified pTHgrttnC. The PCV-1 capsid gene promoter (Pcap) alone was equally effective. Enhancing activity was traced to a putative composite host transcription factor binding site and a "Conserved Late Element" transcription-enhancing sequence previously unidentified in circoviruses.ConclusionsWe identified a novel PCV-1 genome-derived enhancer sequence that significantly increased antigen expression from plasmids in in vitro assays, and improved immunogenicity in mice of the HIV-1 subtype C vaccine plasmid, pTHgrttnC. This should allow significant dose sparing of, or increased responses to, this and other plasmid-based vaccines. We also report investigations of the potential of other circovirus-derived sequences to be similarly used.

Immunogenicity of HIV-1 Vaccines Expressing Chimeric Envelope Glycoproteins on the Surface of Pr55 Gag Virus-Like Particles

“…The chimeric Env sequences were human codon-optimized and synthesized by GenScript (Hong-Kong). The mammalian expression plasmid pTHPcapR [17] was used to construct DNA vaccines pMExT CAP256 gp150-FL-IP, pMExT CAP256 gp120HA 2 -FL, and pMExT CAP256 gp140HA 2 tr-FL-IP. The DNA vaccine expressing the HIV-1 subtype C mosaic Gag, pTJDNA4, has been described previously [18].…”

Characterization and Immunogenicity of HIV Envelope gp140 Zera® Tagged Antigens

“…HEK293T (ATCC R USA, CRL-3216 TM ), HEK293 (ATCC R USA, CRL-1573 TM ) and HeLa (ATCC R USA, CCL-2 TM ) cells were cultured in Dulbecco's modified Eagle medium (DMEM) (high glucose) plus L-glutamine (Lonza) supplemented with heat-inactivated 10% fetal calf serum and penicillin-streptomycin (Pen-Strep) (Gibco). All genes expressed in this study were cloned into the enhanced expression vector pTHpCapR backbone (Tanzer et al, 2011). CAP256 SU V1V2 scaffold protein was provided by Professor Penny Moore (Senior Medical Scientist, Centre for HIV and STIs, National Institute for Communicable Diseases, Johannesburg) and prepared as previously described (van Diepen et al, 2018).…”

“…The CAP256 superinfecting viral envelope (CAP256 SU), modified as described previously by van Diepen et al (2018), was used to generate plasmids encoding gp140-Zera R and Zera R -gp140 (Figure 1). The pTHpCapR mammalian expression vector (Tanzer et al, 2011) was used as a plasmid backbone for both constructs. This plasmid contains a porcine circovirusderived enhancer element upstream of the cytomegalovirus immediate early promoter which drives increased recombinant protein expression.…”

Nanotechnological Approaches for Genetic Immunization

“…Recently, histone deacetylase inhibitors have been supplemented with CMV promoter-based plasmid that has shown increased expression of DNA vaccine antigens (Lai et al 2010 (He et al 2008). The porcine circovirus type 1 capsid gene promoter has enhanced the antigen expression and immunogenicity in a HIV-1 plasmid vaccine (Tanzer et al 2011). Regulation of transcriptional termination is a key element in control of gene expression within the framework of a single transcriptional promoter (Barr et al 2002).…”