A review of vaccine development and research for industry animals in Korea

Lee, Nak-Hyung; Lee, Jung-Ah; Park, Seung-Yong; Song, Chang-Seon; Choi, In-Soo; Lee, Joong-Bok

For examples, the safety and protection efficacy of novel cpxR/lon-deletion mutants of Salmonella species were well demonstrated in chickens and piglets, which included Salmonella Enteritidis strain JOL919 [50] , Salmonella Gallinarum strain JOL 916 [51] , and Salmonella Typhimurium [52, 53] . The immunogenicity of viral proteins displayed on the surface of the vaccine strain Salmonella Ty21a was illustrated, indicating that a bacterial vector may be a delivery vehicle to represent foreign viral proteins as well as self-antigens to a target location, with inducing effective immunity in the vaccinate host [54] . In addition, a global regulator, ppGpp-defective mutant of S. Gallinarum served as a novel vaccine candidate which was able to protect chickens challenged with wild type bacteria [49] . A Salmonella mutant defective in the ruvB gene encoding a Holliday junction helicase showed significant impairment of cell survival and proliferation within epithelial cells and macrophages. The ruvB mutant conferred strong and durable immune-based protection against challenge with virulent strain of S. Typhimurium. This mutant might be a novel live vaccine since its ability to induce protective immunity without causing clinical manifestations [55] . Porcine proliferative enteropathy (PPE) is caused by an obligated intracellular bacteria "Lawsonia intracellularis, " whose virulence and immunological activities are not largely known. Vaccine for PPE was prepared by an attenuated strain derived from a clinical isolate that has been serially passed on cell culture. The phenotype and genetic features of the licensed vaccine strain is not differentiated from those of the field strains. Once the vaccine is orally administered, vaccine was not shed from the host, inducing immune response slightly or not at all. However, shedding of challenged strain in feces of the vaccinated is reduced, showing increased growth performance compared with unvaccinated pigs.