Self-assembly of the JC virus major capsid protein, VP1, expressed in insect cells

• Published in: Journal of general virology Vol. 78; no. 6; pp. 1435 - 1439
• Main Authors: Chang, D, Fung, CY, Ou, WC, Chao, PC, Li, SY, Wang, M, Huang, YL, Tzeng, TY, Tsai, RT
• Format: Journal Article
• Language: English
• Published: England Soc General Microbiol 01-06-1997
• Subjects: Amino Acid Sequence; Animals; Baculoviridae - genetics; Calcium - metabolism; Capsid - chemistry; Capsid - physiology; JC Virus - physiology; Molecular Sequence Data; Recombinant Proteins; Spodoptera; Virus Assembly
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/0022-1317-78-6-1435

D Chang, CY Fung, WC Ou, PC Chao, SY Li, M Wang, YL Huang, TY Tzeng and RT Tsai
Department of Microbiology, Chung Shan Medical and Dental College, Taichung, Taiwan, Republic of China. [e-mail]
The major capsid protein of human polyomavirus JC virus, VP1, has been
cloned into a baculovirus genome and expressed in insect cells. The VP1
protein was expressed in the cytoplasm and transported into the nucleus. It
was then purified by a sucrose cushion and CsCI density gradient
centrifugation to near homogeneity. Electron microscopy showed that
isolated recombinant VP1 protein self-assembled into a capsid-like
structure similar to the natural empty capsid. Both chelator (EDTA) and
reducing agent (DTT) are required to disrupt the capsid structure into the
pentameric capsomeres, as demonstrated by haemagglutination assay and
electron microscopy. These results suggest that JC virus VP1 can be
transported into the nucleus and self-assembled to form capsid-like
particles without the involvement of the viral minor capsid proteins, VP2
and VP3. In addition, metal ions and disulphide bonds appear to be
important in maintaining the integrity of the viral capsid structure.