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, when fusion proteins containing viral antigens were expressed on the surface of oral vaccine strain, S. Typhimurium Ty21a, and inoculated intransally or intraperitoneally into mice, this bacterial carrier vaccine induced mucosal and systemic immunity against multiple viral antigens. Thus, such vaccine strain of Salmonella can play a significant role in delivering foreign vaccine proteins [54] . Virulence-associated genes, K88ac, K99, FasA, F41, and intimin from pathogenic E. coli were individually cloned into an attenuated S. Typhimurium (â–³cpxRâ–³lonâ–³asd). Once such recombinant strains were injected into mice, they were not detected in fecal samples but highly immunogenic [60] . ETEC is responsible for the most common enteric colibacillosis in piglets. A K99 fimbria is known as a specific adhesion factor that is associated with the colonization of ETEC in the small intestine. Recombinant Lactobacillus acidophilus expressing recombinant E. coli K99 fimbriae showed a significant inhibitory effect to E. coli K99, consequently prevented E. coli binding to intestinal brush border [61] . To evaluate the effect of swine interleukine-18 (swIL-18) as an immune modulator for killed vaccine, an attenuated S. Typhimurium expressing swIL-18 was constructed and orally administrated into pigs prior to vaccination with inactivated pseudorabies vaccine. The pigs received swIL-8 by the recombinant Salmonella elicited the enhanced levels of pseudorabies-specific IgG and IgG2 compared to control group. In addition, such immune responses are rapidly elevated and rendered piglets displayed more alleviated clinical signs following challenge with the virulent pseudorabies virus [62] . For PRRSV, the recombinant an attenuated S. Typhimurium expressing the ORF7 protein of PRRSV was constructed and immunized into mice to evaluate its capability of inducing immune responses against PRRSV. Following oral administration of a single dose of the recombinant Salmonella, both humoral and cell-mediated immunity against ORF7 were induced at both systemic and mucosal sites, and were sustained for at least 12 weeks post-immunization [63] .