Immunization with a bicistronic DNA vaccine modulates systemic IFN-γ and IL-10 expression against infection.

Cholera is an acute enteric infection caused by , particularly in areas lacking access to clean water. Despite the global effort to improve water quality in these regions, the burden of cholera in recent years has not yet declined. Interest has therefore extended in the use of bicistronic DNA vaccine encoding and genes of as a potential vaccine. The potential of a bicistronic DNA vaccine, pVAX- has not been determined and . The goal of present study was to evaluate expression and potential of pVAX- vaccine against . The pVAX- was transiently transfected into mammalian COS-7 cells, and the expression was assessed using fluorescence and Western blot analyses. Next, the vaccine was encapsulated into sodium alginate using water-in-oil emulsification and evaluated for its efficiency in different pH conditions. Subsequently, oral vaccination using en(pVAX-) was performed . The animals were challenged with O1 El Tor after 2 weeks of vaccination using the Removable Intestinal Tie-Adult Rabbit Diarrhoea (RITARD) model. Following the infection challenge, the rabbits were monitored for evidence of symptoms, and analysed for systemic cytokine expression level (TNF-α, IFN-γ, IL-6 and IL-10) using quantitative real-time polymerase chain reaction. The expression of pVAX- was successfully verified via fluorescence and Western blot analyses. Meanwhile, analysis demonstrated that the en(pVAX-) was able to protect the RITARD model against infection due to a lack of evidence on the clinical manifestations of cholera following bacterial challenge. Furthermore, the bicistronic group showed an upregulation of systemic IFN-γ and IL-10 following 12 days of vaccination, though not significant, suggesting the possible activation of both T-helper 1 and 2 types of response. However, upon bacterial challenge, the gene expression of all cytokines did not change. Our findings suggest that the bicistronic plasmid DNA vaccine, pVAX-, showed a potential role in inducing immune response against cholera through upregulation of gene and protein expression as well as cytokine gene expression, particularly IFN-γ and IL-10.