Attenuated Salmonella Gallinarum secreting an Escherichia coli heat-labile enterotoxin B subunit protein as an adjuvant for oral vaccination against fowl typhoid

Comparative evaluation of safety and efficacy of a live Salmonella gallinarum vaccine candidate secreting an adjuvant protein with SG9R in chickens

“…However, pBR ori was used as a high copy number plasmid for the construction of the LTB adjuvant strain (JOL1229). An appropriate dilution of vaccine-adjuvant mixture composition is important before administration into birds (Jeon et al, 2012), and safety is still a major concern due to bacterial persistence of the vaccine-adjuvant mixture in the liver and spleen (Jeon et al, 2012). This phenomenon forced us to construct an improved plasmid vector to enable stable expression of LTB in attenuated S. gallinarum (Nandre and Lee, 2014a).…”

“…Cellular immune responses are required to control SG infections , and the correlation between cellular immunity and high survival rates in chickens after virulent SG challenge has been described previously Jeon et al, 2012). To evaluate cellular immune responses, we used an antigenspecific lymphocyte proliferation assay and enumerated CD3+CD4+ and CD3+CD8+ T cells after booster immunization.…”

“…The presence of each strain was also examined in the liver, spleen and caeca from three birds per each group at 1, 3, 7, 14 and 21 days post-immunization. Specifically, each strain was confirmed by PCR using OMPC primers for the Salmonella genus, SG primers for Salmonella gallinarum, lon and cpxR primers for JOL916, and LTB primers for JOL1355 (Alvarez et al, 2004;Kang et al, 2011;Jeon et al, 2012). Bacterial recovery from liver, spleen and caeca samples was examined as previously described .…”

“…In our previous studies, we used live attenuated SG secreting LTB (JOL1229) as an adjuvant for JOL916 (Jeon et al, 2012(Jeon et al, , 2013. However, such adjuvant-vaccine compositions may be inconvenient to implement in the poultry industry due to uneconomical formulations.…”

“…However, such adjuvant-vaccine compositions may be inconvenient to implement in the poultry industry due to uneconomical formulations. In addition, bacterial recovery was observed in the internal organs of chickens after immunization with this composition (Jeon et al, 2012). In our previous study, we constructed JOL1355, a live SG secreting LTB, by transforming a low copy number plasmid (p15A ori) with eltB encoding LTB into the attenuated SG strain ( lon cpxR asd) (Nandre and Lee, 2014a).…”