The multi-fragment antigen (BE) may represent a promising alternative to the whole virus without safety problems, and this newly established ELISA provides an effective method for anti-IBV antibody detection.

(2015) Development of a multi-epitope antigen of S protein-based ELISA for antibodies detection against infectious bronchitis virus, Bioscience, Biotechnology, and Biochemistry, 79:8, 1287-1295,

Mucosal immunity is critical in preventing infectious bronchitis virus (IBV) infection. To deliver viral antigens to the mucosal immune system of chickens safely and effectively, we constructed a Lactococcus lactis strain carrying IBV multi-epitope gene EpiC fused with the gene of the cell-wall anchoring domain of Staphylococcus aureus protein A. SDS-PAGE and Western blot results indicated that the fused peptide was located partially on the cell surface. Oral and nasal inoculation with the recombinant L. lactis of chickens elicited significantly high humoral and mucosal immune responses, especially in the nasally immunized group. Eighty percent chickens of the nasally immunized group with recombinant L. lactis did not show any clinical signs after a lethal dose challenge with IBV SAIBk strain, while all the non-recombinant L. lactis immunized chickens exhibited obvious and typical symptoms. These results indicate that needle-free recombinant lactococci anchoring the IBV antigen makes a promising vaccine candidate against the spread of IB.

The avian infectious bronchitis virus (IBV) multi-epitope based peptide EpiC was found to be effective in inducing strong humoral and cellular responses against IBV. In this study, the gene EpiC was introduced into Lactococcus lactis NZ3900, and three recombinant strains expressing EpiC in intracellular and extracellular forms were constructed. SDS-PAGE and Western blot results indicated that EpiC was successfully expressed and had good immunoreactivity with chicken anti-IBV serum. Fusion of the signal pepitide gene SPusp45 and the nine-peptide LEISSTCDA encoding oligonucleotide to EpiC increased the secretion of EpiC, but reduced the total yields of EpiC. Oral immunization to specific-pathogen-free (SPF) chickens with recombinant strains induced significantly higher levels of humoral immune responses, and provided protection against lethal dose challenge by the IBV SAIBk strain. These results indicate that it is feasible to use L. lactis as an antigen delivery vehicle in developing oral vaccines against IBV infection.

To obtain adhesive and safe lactic acid bacteria (LAB) strains for expressing heterologous antigens, we screened LAB inhabitants in intestine of Tibetan chickens by analyzing their adhesion and safety properties and the selected LAB was engineered to express heterologous antigen (UTEpi C-A) based on chromosomal integration strategy. We demonstrated that a new Lactobacillu salivarius TCMM17 strain is strongly adhesive to chicken intestinal epithelial cells, contains no endogenous plasmids, is susceptible to tested antimicrobials, and shows no toxicities. In order to examine the potential of TCMM17 strain as heterogenous antigen delivering vehicle, we introduced a UTEpi C-A expression cassette in its chromosome by constructing a non-replicative plasmid (pORI280-UUTEpi C-AD). The recombinant TCMM17 strain (∆TCMM17) stably was found to keep the gene cassette through 50 generations, and successfully displayed EpiC encoded by the cassette on its surface. This work provides a universal platform for development of novel oral vaccines and expression of further antigens of avian pathogens.