Oral vaccination with attenuated Salmonella enterica serovar Typhimurium expressing Cap protein of PCV2 and its immunogenicity in mouse and swine models.
Attenuated Salmonella enterica serovar Typhimurium (S. typhimurium) was selected as a transgenic vehicle for the development of oral vaccines against Porcine circovirus type 2 (PCV2). The Cap-encoding gene of PCV2 was amplified by PCR and cloned into expression vector pYA3341. The recombinant plasmid pYA3341-Cap was transformed into attenuated S. typhimurium X4550. BALB/c mice were inoculated orally with various doses of attenuated S. typhimurium X4550/pYA3341-Cap. The bacterium was safe to mice at dose of 2×10(9)cfu and eventually eliminated in the spleen and mesenteric lymph nodes at 4 weeks post-immunization. The flow cytometry analysis showed that the percentage of CD4(+) T cells and CD4(+)/CD8(+) ratio were increased significantly in mice immunized with attenuated S. typhimurium X4550/pYA3341-Cap. Vaccine tests in swine showed that the oral immunization with attenuated S. typhimurium X4550/pYA3341-Cap could elicit significantly higher Cap antibody titers in the treated swine than the control groups. Virus neutralization test showed that serum from the swine treated with attenuated S. typhimurium X4550/pYA3341-Cap had significant levels of neutralization activities. The swine lymphocyte proliferative responses indicated that attenuated S. typhimurium X4550/pYA3341-Cap could induce obvious cellular immune response. An in vivo challenge study showed the swine treated with attenuated S. typhimurium X4550/pYA3341-Cap had significantly lower PCV2-associated lesions and PCV2 viremia than the control groups. The results indicated that attenuated S. typhimurium X4550/pYA3341-Cap can be a potential vaccine against PCV2 infections.
College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
Xin-Gang
XG
Xu
Hong-Ni
HN
Zhao
Qi
Q
Zhang
Li
L
Ding
Zhao-Cai
ZC
Li
Wei
W
Li
Hung-Yi
HY
Wu
Kuo-Pin
KP
Chuang
De-Wen
DW
Tong
Hung-Jen
HJ
Liu
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000917:Antibody Formation; D016516:CD4-CD8 Ratio; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology*; D018173:Circoviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D017925:Circovirus / Q000276:immunology*; D005260:Female; D007111:Immunity, Cellular; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D010957:Plasmids; D012486:Salmonella typhimurium / Q000235:genetics / Q000276:immunology*; D013552:Swine / Q000276:immunology; D013553:Swine Diseases / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014611:Vaccination; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology*
D000914:Antibodies, Viral; D036022:Capsid Proteins; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D014765:Viral Vaccines