Oral and intranasal administration of somatostatin DNA vaccine mediated by attenuated Salmonella Enterica Serovar Typhimurium to promote growth of piglets

Abstract

An attenuated strain of Salmonella typhimurium has been used as a carrier for oral and intranasal genetic immunization. Here, we evaluate the efficacy of a vaccine strain of S. typhimurium. CSO22 (pGM-CSF/SS, plasmid granulocyte-macrophage colonystimulating factor/somatostatin) expressing two copies of SS genes. A total of 115 piglets, aged 2 months old, were either orally or intranasally immunized against the vaccine strain CSO22 (pGM-CSF/SS) with three dosages (5 3 10 10 colony forming units (CFU), 5 3 10 9 CFU and 5 3 10 8 CFU). For oral immunization, the specific anti-SS antibodies were detected in the immunized piglets. The levels of SS antibodies in the high-dose immunized group (5 3 10 10 CFU) were significantly higher than that in the phosphate buffered saline immunized group (P , 0.01) and 40% of animals were positive in SS antibodies in the high-dose immunized group. Moreover, the weight gain of the high-dose group was increased by 20.86%, 10.26% and 15.30% during 4, 8 and 12 weeks, respectively, after immunization in comparison to the control. For intranasal immunization, the growth of the lowdose group was increased by 10.23% in the whole test period (12 weeks). In conclusion, our results suggest that the recombinant strain could elicit anti-SS antibodies and improve the growth performance of immunized piglets, and that the oral immunization program is better than the intranasal program.

Efficacy and Safety of an Oral Somatostatin DNA Vaccine without Antibiotic Resistance Gene in Promoting Growth of Piglets

“…Liu et al . have also found that weight gain by piglets was only in the high‐dose orally immunized group against the SS DNA vaccine CSO22 (pGM‐CSF/SS) significantly higher compared to the control group at week 4 after primary immunization ( P < 0.05). The increase in growth rate in the high‐dose orally immunized group was also decreased at week 8 (20.86%) compared with week 4 (10.26%) after primary immunization.…”

“…Attenuated Salmonella was selected as an attractive delivery vector of heterologous antigens for oral immunization that could elicit systemic and mucosal immune responses . In previous studies, the oral SS DNA vaccine CSO22 (pGM‐CSF/SS) delivered by attenuated Salmonella typhimurium successfully induced antibody responses against SS and enhanced the growth of immunized mice and piglets . However, there was an antibiotic resistance gene in the CSO22 (pGM‐CSF/SS) that may cause antibiotic resistance and environmental problems.…”

“…In this study, there were significant positive correlations between anti‐SS antibodies, GH and average daily gain, and there were significant negative correlations between the content in serum of SS levels, anti‐SS antibodies, GH and average daily gain. Although enhanced growth rates were reported with active or passive immunization against SS , the mechanism for somatostatin vaccine action is still not explicit. There were two possible mechanisms for the effect of SS immunoneutralization.…”

“…It is convenient and low cost to use Salmonella as a vehicle for DNA vaccine immunization as there is no need for further plasmid amplification and purification steps . The recombinant attenuated Salmonella typhimurium strains containing the eukaryotic expression plasmid encoding SS gene fused with S gene have been applied to immunize animals for promoting the growth by oral or intranasal immunization . However, after oral administration, the live attenuated Salmonella strain can spread in the natural environment by stool , thereby it may cause environmental contamination and reversion to virulent type through survival ex vivo .…”

Comparative efficacy of a multi-epitope DNA vaccine via intranasal, peroral, and intramuscular delivery against lethal Toxoplasma gondii infection in mice

“…Recombinant Salmonella have been used as vaccine vectors to deliver both DNA and protein vaccines from a wide variety of bacterial, viral and parasitic sources [16,17]. Attenuation virulence bacteria, which can penetrate host cells delivering vaccine antigen to APCs, can be used effectively to transport immunogens [18,19]. …”