AttenuatedSalmonella typhimuriumSV4089 as a Potential Carrier of Oral DNA Vaccine in Chickens

Abstract

Attenuated Salmonella has been used as a carrier for DNA vaccine. However, in vitro and in vivo studies on the bacteria following transfection of plasmid DNA were poorly studied. In this paper, eukaryotic expression plasmids encoding avian influenza virus (AIV) subtype H5N1 genes, pcDNA3.1/HA, NA, and NP, were transfected into an attenuated Salmonella enteric typhimurium SV4089. In vitro stability of the transfected plasmids into Salmonella were over 90% after 100 generations. The attenuated Salmonella were able to invade MCF-7 (1.2%) and MCF-10A (0.5%) human breast cancer cells. Newly hatched specific-pathogen-free (SPF) chicks were inoculated once by oral gavage with 109 colony-forming unit (CFU) of the attenuated Salmonella. No abnormal clinical signs or deaths were recorded after inoculation. Viable bacteria were detected 3 days after inoculation by plating from spleen, liver, and cecum. Fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) were carried out for confirmation. Salmonella was not detected in blood cultures although serum antibody immune responses to Salmonella O antiserum group D1 factor 1, 9, and 12 antigens were observed in all the inoculated chickens after 7 days up to 35 days. Our results showed that live attenuated S. typhimurium SV4089 harboring pcDNA3.1/HA, NA, and NP may provide a unique alternative as a carrier for DNA oral vaccine in chickens.

Recombinant-attenuated Salmonella Pullorum strain expressing the hemagglutinin-neuraminidase protein of Newcastle disease virus (NDV) protects chickens against NDV and Salmonella Pullorum challenge

“…Recent studies have shown that live attenuated Salmonella is an effective vector for delivery of heterologous antigens or DNA to the immune system [ 17 18 23 37 ]. In addition, live vectors can mimic the natural process of Salmonella infection through the oral route, resulting in mucosal and systemic immune responses against the pathogen's antigen [ 7 ].…”

Recent advances in delivery of veterinary DNA vaccines against avian pathogens

“…DNA vaccines are inexpensive to produce in large doses and are easily detected and monitored after oral inoculations into the host. Furthermore, attenuated S. typhimurium SV4089 was able to invade and pass through the various organs of inoculated chickens, such as the liver, spleen, and caecum, without showing evidence of systemic infection [64].…”

Vaccination against Trichinella spiralis: Potential, Limitations and Future Directions

“…In this regard, Salmonella-based vaccine systems are considered among the most advanced and promising technologies developed to induce immunological protection against enteric pathogens because of their ability to both colonize the small intestine and invade non-phagocytic epithelial cells, thus allowing access to the underlying lymphoid tissue [32]. Taking advance of the use of Salmonella as live bacterial carrier, our group developed a Salmonella vaccine candidate expressing the 30-mer peptide derived from gp43 (amino acid residues 210-239, designated as Ag30) from T. spiralis ML.…”