Protective immunity against porcine circovirus 2 by vaccination with ORF2-based DNA and subunit vaccines in mice.
The protective immune response against porcine circovirus 2 (PCV2) infection in mice was characterized using flow cytometric analysis (FCM), assays of antibody (of different IgG isotypes) and viraemia, and histopathological examination. An open reading frame 2 plasmid (pORF2) and the capsid protein (Cap) of PCV2 were used as DNA and subunit vaccines, respectively. In FCM analysis, although pORF2 and Cap alone showed comparable efficacy in eliciting lymphoproliferative responses and Cap-specific CD4(+) T cells, pORF2 was superior to the Cap protein in triggering CD8(+) T cells. A virus neutralization assay showed that pORF2 evoked stronger recall virus-neutralizing (VN) antibody responses than the Cap protein on PCV2 challenge. Correspondingly, VN antibody kinetics coincided with those of Cap-specific IgG2a, but not with the kinetics of IgG and IgG1. Following virus challenge, real-time PCR and histopathological analysis confirmed that only low viral DNA loads and mild microscopic lesions appeared in pORF2-immunized mice. These findings indicate that CD8(+) T cells and VN antibody responses correlating mainly with Cap-specific IgG2a play crucial roles in protecting against PCV2 infection, and that the protective immunity induced by the pORF2 plasmid is superior to that induced by the PCV2 Cap protein.
Shen
Hui-Gang
HG
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003, PR China.|Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
Zhou
Ji-Yong
JY
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003, PR China.|Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
Huang
Zhen-Yu
ZY
Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
Guo
Jun-Qing
JQ
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003, PR China.|Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
Xing
Gang
G
Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
He
Jia-Ling
JL
Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
Yan
Yan
Y
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003, PR China.|Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
Gong
Li-Yang
LY
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003, PR China.|Laboratory of Virology and Immunology, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China.
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D018173:Circoviridae Infections / Q000276:immunology / Q000473:pathology / Q000517:prevention & control / Q000821:virology; D017925:Circovirus / Q000145:classification / Q000276:immunology*; D004279:DNA, Viral / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D016366:Open Reading Frames / Q000235:genetics / Q000276:immunology*; D010957:Plasmids; D014611:Vaccination; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014766:Viremia / Q000276:immunology / Q000517:prevention & control
D000914:Antibodies, Viral; D036022:Capsid Proteins; D004279:DNA, Viral; D019444:Vaccines, DNA; D022223:Vaccines, Subunit