Immune responses against SARS-coronavirus nucleocapsid protein induced by DNA vaccine.
The nucleocapsid (N) protein of SARS-coronavirus (SARS-CoV) is the key protein for the formation of the helical nucleocapsid during virion assembly. This protein is believed to be more conserved than other proteins of the virus, such as spike and membrane glycoprotein. In this study, the N protein of SARS-CoV was expressed in Escherichia coli DH5alpha and identified with pooled sera from patients in the convalescence phase of SARS. A plasmid pCI-N, encoding the full-length N gene of SARS-CoV, was constructed. Expression of the N protein was observed in COS1 cells following transfection with pCI-N. The immune responses induced by intramuscular immunization with pCI-N were evaluated in a murine model. Serum anti-N immunoglobulins and splenocytes proliferative responses against N protein were observed in immunized BALB/c mice. The major immunoglobulin G subclass recognizing N protein was immunoglobulin G2a, and stimulated splenocytes secreted high levels of gamma interferon and IL-2 in response to N protein. More importantly, the immunized mice produced strong delayed-type hypersensitivity (DTH) and CD8(+) CTL responses to N protein. The study shows that N protein of SARS-CoV not only is an important B cell immunogen, but also can elicit broad-based cellular immune responses. The results indicate that the N protein may be of potential value in vaccine development for specific prophylaxis and treatment against SARS.
Zhao
Ping
P
Department of Microbiology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, China.
Cao
Jie
J
Zhao
Lan-Juan
LJ
Qin
Zhao-Lin
ZL
Ke
Jin-Shan
JS
Pan
Wei
W
Ren
Hao
H
Yu
Jian-Guo
JG
Qi
Zhong-Tian
ZT
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000097:blood; D019556:COS Cells; D002455:Cell Division / Q000276:immunology; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D016207:Cytokines / Q000378:metabolism; D004926:Escherichia coli; D005260:Female; D006968:Hypersensitivity, Delayed / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D019590:Nucleocapsid Proteins / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D045473:Severe acute respiratory syndrome-related coronavirus / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D019444:Vaccines, DNA / Q000009:adverse effects / Q000276:immunology*; D014765:Viral Vaccines / Q000009:adverse effects / Q000276:immunology*
D000914:Antibodies, Viral; D016207:Cytokines; D019590:Nucleocapsid Proteins; D011994:Recombinant Proteins; D019444:Vaccines, DNA; D014765:Viral Vaccines