Immunogenicity of the capsid precursor and a nine-amino-acid site-directed mutant of the 3C protease of foot-and-mouth disease virus coexpressed by a recombinant goatpox virus.
The myristoylated capsid precursor mP1-2A of foot-and-mouth disease virus (FMDV), when expressed in mammalian cells and processed by the FMDV 3C protease, can self-assemble into virus-like particles (VLPs). In the present study, nine amino acids of the 3C protease were replaced by site-directed mutagenesis to create a mutant 3C protease, 9m3C. To coexpress mP1-2A and 9m3C and test the resulting proteolytic processing and VLP assembly, two recombinant goatpox viruses (rGTPVs) were constructed by the insertion of two coding regions, one for mP1-2A and the other for either 9m3C (rGTPV-mP1-2A-9m3C) or Theileria protective antigen (TPA) as a control (rGTPV-mP1-2A-TPA). The two exogenous genes were inserted into an intergenic region between loci gp_24 and gp_24.5 of the rGTPV genome. Western blotting of cells infected with rGTPV-mP1-2A-9m3C showed that proteins VP0, VP1, and VP3 from the mP1-2A processed by the 9m3C protease could be detected by polyclonal FMDV sera. As observed by electron microscopy, the infected cells produced VLPs with a diameter of about 25 ± 2 nm. Titers of neutralizing antibody against FMDV were significantly higher in mice inoculated with rGTPV-mP1-2A-9m3C, which expresses the 9m3C protease together with mP1-2A, than mice inoculated with the control rGTPV-mP1-2A-TPA, which does not express the protease. An ovine immunization test determined that sheep inoculated intramuscularly with rGTPV-mP1-2A-9m3C produced FMDV-specific neutralizing antibody, but its titers did not meet the requirement of the World Organization for Animal Health. The result indicates that further modifications of rGTPV-mP1-2A-9m3C are necessary to produce an effective vaccine.
Institute of Veterinary Medicine, Xinjiang Academy of Animal Science, 151 Eastern Kelamayi Street, Ürümqi, 830000, People's Republic of China, mawenge2004@aliyun.com.
Wenge
W
Ma
Jie
J
Wei
Yurong
Y
Wei
Huiling
H
Guo
Yinghong
Y
Jin
Ying
Y
Xue
Yan
Y
Wang
Zhong
Z
Yi
Liya
L
Liu
Jiong
J
Huang
Lijian
L
Wang
D000086042:3C Viral Proteases; D000595:Amino Acid Sequence; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D018151:Capripoxvirus / Q000235:genetics / Q000378:metabolism*; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D005260:Female; D029544:Foot-and-Mouth Disease Virus / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D014614:Vaccines, Synthetic / Q000276:immunology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014765:Viral Vaccines / Q000276:immunology*
D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D014614:Vaccines, Synthetic; D014764:Viral Proteins; D014765:Viral Vaccines; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases