Protective immunity against porcine circovirus 2 in mice induced by a gene-based combination vaccination.
BACKGROUND
Porcine circovirus type 2 (PCV2) is the primary cause of an emerging swine disease, postweaning multisystemic wasting syndrome, that is responsible for economic losses. To develop an effective vaccine for PCV2, we evaluated a heterologous prime-boost vaccine approach, using a gene gun-mediated naked DNA vector as a priming and modified vaccinia virus ankara (MVA) as a booster, in Balb/c mice.


METHODS
Three open reading frames (ORF) of PCV2 viral samples from infected pigs were amplified, and gene gun-mediated DNA priming vaccination was performed followed by boosts with MVA vectors expressing the same ORFs of PCV2. After vaccination, mice were challenged with PCV2 virus, and virus titers in the lungs and lymph nodes were measured.


RESULTS
The combination of ORF-2 and -3 in this gene-based vaccine strategy resulted in high antibody titers and virus neutralization activity in serum, reduced PCV2 virus load, and reduced levels of apoptosis in the lungs. No cross-reaction was observed between ORF-1 and -2, but weak cross-reaction was observed between ORF-1 and -3, and between ORF-2 and -3. Following vaccination, expression of chemokines, macrophage inflammatory protein-1beta and regulated upon activation, normal T cell expressed and secreted, increased significantly. The expression of T helper 1-type cytokine (interferon-gamma) and specific lysis of PCV2-infected cells increased; concomitantly, the level of T helper 2-type cytokine (interleukin-10) decreased in test mice. The expression of tumor necrosis factor-alpha and granulocyte-macrophage colony-stimulating factor increased significantly in mice vaccinated with ORF-2/-3, and with ORF-1/-2/-3.


CONCLUSIONS
This prime-boost vaccination strategy, using a gene gun for DNA priming and recombinant MVA for boosts, may be an attractive vaccine strategy against PCV2 infection in swine.
Aravindaram
Kandan
K
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan.
Kuo
Tsun-Yung
TY
Lan
Chun-Wen
CW
Yu
Hsiu-Hui
HH
Wang
Pei-Hsueh
PH
Chen
Yu-San
YS
Chen
Gabriel Hsu-Chung
GH
Yang
Ning-Sun
NS
D000818:Animals; D018173:Circoviridae Infections / Q000517:prevention & control*; D017925:Circovirus / Q000235:genetics / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D004279:DNA, Viral / Q000008:administration & dosage* / Q000627:therapeutic use; D015316:Genetic Therapy / Q000379:methods; D007109:Immunity; D051379:Mice; D008807:Mice, Inbred BALB C; D053570:Porcine Postweaning Multisystemic Wasting Syndrome / Q000517:prevention & control; D013552:Swine; D013601:T-Lymphocytes / Q000276:immunology; D016896:Treatment Outcome; D017778:Vaccines, Combined / Q000008:administration & dosage* / Q000276:immunology; D014616:Vaccinia virus / Q000235:genetics
D016207:Cytokines; D004279:DNA, Viral; D017778:Vaccines, Combined