Evaluation of the Effect of Promoter Type on the Immunogenicity of the Live Recombinant <i>Salmonella</i> Vaccines Expressing <i>Escherichia Coli</i> Heat-labile Enterotoxins (LTB)
| Author | Elham Mohit | en |
| Author | Reza Nasr | en |
| Author | Kiarash Ghazvini | en |
| Author | Ahmad Reza Bandegi | en |
| Author | Mohammad Reza Akbari Eidgahi | en |
| Issued Date | 2018-12-31 | en |
| Abstract | Enterotoxigenic Escherichia coli (ETEC)-induced diarrhoea is the second most common cause of death in children in the developing countries. Heat labile toxin (LT) is responsible for ETEC-induced diarrhoea. In the present study, a novel live ETEC vaccine based on subunit B of LT (LTB) expression in attenuated PhoPcSalmonella strain was developed. Herein, we aimed to compare the in-vitro activity of promoters including constitutive tac, IPTG inducible trc, and in-vivo-inducible (nirB and nirB78-23) in PhoPc. Additionally, the ability of these recombinant PhoPc/pLTBs to induce LTB-specific antibody responses in BALB/c mice after nasal immunization was evaluated. In-vitro studies demonstrated that PhoPc has the ability to produce rLTB. Furthermore, nirB promoter directed significantly more LTB expression in PhoPc/pnirBLTB under anaerobic condition without induction compared to the amount of rLTB secreted by PhoPc/ptrcLTB in bacterial soup under uninduced condition (6.06 ± 0.05 vs. 1.4 ± 0.46 μg/109 cfu, p < 0.01). In addition, the constitutive rLTB expression from tac promoter was more than its expression from uninduced trc promoter in bacterial soup (4.2 ± 0.92 vs. 1.4 ± 0.46 (μg/109 cfu)) and pellet (27.4 ± 0.89 vs. 13.4 ± 1.42 (μg/109 cfu), p < 0.0001). However, the mice immunized with PhoPc/ptrcLTB elicited the superior anti-LTB responses among the PhoPc containing the examined prompters, which were significantly higher than those induced by PhoPc/pnirB78-23LTB and PhoPc/pnirB, 6 weeks after the first immunization. Totally, it could be concluded that in-vitro analysis of promoters for LTB expression in PhoPc may not necessarily predict the recombinant PhoPc immunogenicity. | en |
| DOI | https://doi.org/10.22037/ijpr.2018.2366 | en |
| Keyword | Attenuated Salmonella | en |
| Keyword | ETEC | en |
| Keyword | Live vaccine | en |
| Keyword | LTB | en |
| Keyword | Promoter | en |
| Keyword | <i>nir</i>B | en |
| Keyword | PhoP<sup>c</sup> | en |
| Publisher | Brieflands | en |
| Title | Evaluation of the Effect of Promoter Type on the Immunogenicity of the Live Recombinant <i>Salmonella</i> Vaccines Expressing <i>Escherichia Coli</i> Heat-labile Enterotoxins (LTB) | en |
| Type | Original Article | en |