Prokaryotic expression and potential application of the truncated PCV-2 capsid protein.
Three pairs of specific primers were designed to amplify the F2-1, F2-2 and XF2-2 truncated sequences of ORF2 which encodes the capsid protein of porcine circovirus type 2 (PCV-2). The F2-1 sequence had most of the NLS region of ORF2, but the F2-2 and XF2-2 genes had the NLS region deleted. Truncated genes were subcloned into pET-32a(+) vectors to construct recombinant fusion expression vectors. The vectors were then transformed into Rosetta(DE3) E. coli and expressed by induction of IPTG. Expressed proteins were detected by western blotting and ELISA. The protein with best immunoreactivity was confirmed and selected, then utilized to inoculate SPF rabbits to prepare polyclonal antibodies. The protein and prepared polyclonal antibody were utilized to detect sera samples against PCV-2 from Shandong province and PCV-2 particles in PK-15 cells. In our study, three recombinant fusion proteins were successfully obtained, and the molecular weights of fusion proteins were 35.9 kDa, 33.6 kDa and 38.6 kDa respectively detected by SDS-PAGE. All of the proteins showed positive reaction with anti-PCV-2 antisera, and His-XF2-2 showed better immunoreactivity than the others. The protein of His-XF2-2 was coated as antigen in ELISA to detect the seroprevalence of PCV-2 in certain districts of Shandong province, the seropositivity rate was 27.7 % (73/264). Specific fluorescence and positive signals for PCV-2 could be detected in PK-15 cells inoculated with PCV-2 with the participation of prepared antibodies against His-XF2-2 in IFA and IPMA. Experimental results indicated that the truncated PCV-2 ORF2 gene containing most of the NLS region was successfully expressed in E. coli, and His-XF2-2 was demonstrated to have better immunoreactivity with anti-PCV-2 antisera than the other two fusion proteins. His-XF2-2 and prepared polyclonal antibodies against it had a satisfactory capability in detecting PCV-2 infection.
Animal Infectious Diseases Research Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China.
Zhong-zi
ZZ
Lou
Zhi-yong
ZY
Li
Gang
G
Wang
Jian-qiang
JQ
Li
Xi
X
Lan
Xue-rui
XR
Li
Xiang-ping
XP
Yin
Ji-xing
JX
Liu
Si-dang
SD
Liu
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood / Q000302:isolation & purification; D000956:Antigens, Viral / Q000096:biosynthesis / Q000235:genetics; D036022:Capsid Proteins / Q000096:biosynthesis / Q000235:genetics; D002460:Cell Line; D002681:China / Q000453:epidemiology; D018173:Circoviridae Infections / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D017925:Circovirus / Q000235:genetics / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005822:Genetic Vectors; D008970:Molecular Weight; D010957:Plasmids; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D017384:Sequence Deletion; D016036:Seroepidemiologic Studies; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis* / Q000453:epidemiology* / Q000821:virology
D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D011993:Recombinant Fusion Proteins