Development of Rift Valley fever (RVF) vaccine by genetic joining of the RVF-glycoprotein Gn with the strong adjuvant subunit B of cholera toxin (CTB) and expression in bacterial system

Abstract

One of the mosquito-borne zoonotic diseases is the Rift Valley fever virus (RVFV). Currently, there is no completely licensed vaccine that can be used to vaccinate animals or humans outside endemic areas. The aim of this work was to use the RVFV glycoprotein (Gn) and the subunit B of cholera toxin (CTB) at gene level and build up fused recombinant vaccine. The gene of CTB was joined to the gene Gn to work as an adjuvant in the resulting fusion protein. The designed merged genes (CTB-Gn) was tested for restriction sites, open reading frames, expected fusion protein tertiary structure and antigenicity using computer software. The insert sequence was submitted to the BioProject (GenBank). The insert was subcloned into the pQE-31 expression plasmid. The target recombinant protein (rCTB-Gn) was expressed in M15 bacteria, purified and identified by protein gel electrophoresis. The insert got the accession No: PRJNA386723. Analysis of the designed rCTB-Gn protein revealed that it had the right 3D structure, immunogenic and at the correct molecular weight. The presence of the CTB in the proposed vaccine will augment its immunogenicity. Doses and protection levels of the vaccine need to be manipulated.

Keywords: Adjuvant; CTB; RVFV; Recombinant vaccine; Subunit vaccine.

Fig. 1

Schematic representation showing cloning of CTB and Gn into pUC57.

Fig. 2

Restriction enzyme digestion of recombinant pUC57 using SphI and SmaI enxymes. Lane 1: undigested recombinant pUC57; lane 2: digested recombinant pUC57 and lane M: KB ladder.

Fig. 3

CTB-Gn protein expression and purification. Lane 1: Uninduced culture, lane 2: induced culture, lane 3: crude lysate, lane 4: flow through, lane M: Perfect Protein™ Markers (10–225 kDa), lane 5–9: elution fractions.