An Alphavirus Replicon Particle Chimera Derived from Venezuelan Equine Encephalitis and Sindbis Viruses Is a Potent Gene-Based Vaccine Delivery Vector

Abstract

Alphavirus replicon particle-based vaccine vectors derived from Sindbis virus (SIN), Semliki Forest virus,and Venezuelan equine encephalitis virus (VEE) have been shown to induce robust antigen-specific cellular, humoral, and mucosal immune responses in many animal models of infectious disease and cancer. However, since little is known about the relative potencies among these different vectors, we compared the immunogenicity of replicon particle vectors derived from two very different parental alphaviruses, VEE and SIN, expressing a human immunodeficiency virus type 1 p55Gag antigen. Moreover, to explore the potential benefits of combining elements from different alphaviruses, we generated replicon particle chimeras of SIN and VEE. Two distinct strategies were used to produce particles with VEE-p55 gag replicon RNA packaged within SIN envelope glycoproteins and SIN-p55 gag replicon RNA within VEE envelope glycoproteins. Each replicon particle configuration induced Gag-specific CD8 ؉ T-cell responses in murine models when administered alone or after priming with DNA. However, Gag-specific responses varied dramatically, with the strongest responses to this particular antigen correlating with the VEE replicon RNA, irrespective of the source of envelope glycoproteins. Comparing the replicons with respect to heterologous gene expression levels and sensitivity to alpha/ beta interferon in cultured cells indicated that each might contribute to potency differences. This work shows that combining desirable elements from VEE and SIN into a replicon particle chimera may be a valuable approach toward the goal of developing vaccine vectors with optimal in vivo potency, ease of production, and safety.

Induction of an IFN-Mediated Antiviral Response by a Self-Amplifying RNA Vaccine: Implications for Vaccine Design

“…Viral replicon particles (VRPs) were generated in baby hamster kidney (BHK) cells as previously described (14). Ag-expressing (or reporter geneexpressing) replicons derived from the Venezuelan equine encephalitis virus genome containing the 39 untranslated region and packaging signal of Sindbis virus (SV) were electroporated into BHK cells along with defective helper RNAs encoding the SV capsid and glycoprotein genes (10).…”

Nonviral delivery of self-amplifying RNA vaccines

“…For these studies, we used a self-amplifying RNA based on an alphavirus genome (10), which contains the genes encoding the alphavirus RNA replication machinery, but lacks the genes encoding the viral structural proteins required to make an infectious alphavirus particle (Fig. 1A).…”

Analysis of human immunodeficiency virus type 1 vector cis- and trans-acting elements production by means of Semliki Forest virus

“…Indeed, in the case of SFV/HIV CAT , the presence of an SFV capsid protein would be expected to allow selectivity in viral genome packaging in SFV/ HIV CAT particles, even though several evidence has suggested that, besides the specific interaction of the alphavirus capsid with packaging signals, some other mechanism(s) might be involved in RNA packaging. 42,43 One important consideration might be the effect of the SFV/HIV CAT vector expression level in the co-transduced cells. However, even though the expression of the SFV/HIV CAT vector in transfected cells was not particularly high, efficient transducing ability of SFV/HIV CAT particles was achieved.…”