Antigenic analysis of classical swine fever virus E2 glycoprotein using pig antibodies identifies residues contributing to antigenic variation of the vaccine C-strain and group 2 strains circulating in China

Virology Journal - Tập 7 - Trang 1-14 - 2010
Ning Chen1, Chao Tong1, Dejiang Li1, Jing Wan1, Xuemei Yuan1, Xiaoliang Li1, Jinrong Peng1, Weihuan Fang1
1Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, PR China

Tóm tắt

Glycoprotein E2, the immunodominant protein of classical swine fever virus (CSFV), can induce neutralizing antibodies and confer protective immunity in pigs. Our previous phylogenetic analysis showed that subgroup 2.1 viruses branched away from subgroup 1.1, the vaccine C-strain lineage, and became dominant in China. The E2 glycoproteins of CSFV C-strain and recent subgroup 2.1 field isolates are genetically different. However, it has not been clearly demonstrated how this diversity affects antigenicity of the protein. Antigenic variation of glycoprotein E2 was observed not only between CSFV vaccine C-strain and subgroup 2.1 strains, but also among strains of the same subgroup 2.1 as determined by ELISA-based binding assay using pig antisera to the C-strain and a representative subgroup 2.1 strain QZ-07 currently circulating in China. Antigenic incompatibility of E2 proteins markedly reduced neutralization efficiency against heterologous strains. Single amino acid substitutions of D705N, L709P, G713E, N723S, and S779A on C-strain recombinant E2 (rE2) proteins significantly increased heterologous binding to anti-QZ-07 serum, suggesting that these residues may be responsible for the antigenic variation between the C-strain and subgroup 2.1 strains. Notably, a G713E substitution caused the most dramatic enhancement of binding of the variant C-strain rE2 protein to anti-QZ-07 serum. Multiple sequence alignment revealed that the glutamic acid residue at this position is conserved within group 2 strains, while the glycine residue is invariant among the vaccine strains, highlighting the role of the residue at this position as a major determinant of antigenic variation of E2. A variant Simpson's index analysis showed that both codons and amino acids of the residues contributing to antigenic variation have undergone similar diversification. These results demonstrate that CSFV vaccine C-strain and group 2 strains circulating in China differ in the antigenicity of their E2 glycoproteins. Systematic site-directed mutagenesis of the antigenic units has revealed residues that limit cross-reactivity. Our findings may be useful for the development of serological differential assays and improvement of immunogenicity of novel classical swine fever vaccines.

Tài liệu tham khảo

Moennig V: Introduction to classical swine fever: virus, disease and control policy. Vet Microbiol 2000, 73: 93-102. 10.1016/S0378-1135(00)00137-1

Becher P, Avalos Ramirez R, Orlich M, Cedillo Rosales S, Konig M, Schweizer M, Stalder H, Schirrmeier H, Thiel HJ: Genetic and antigenic characterization of novel pestivirus genotypes: implications for classification. Virology 2003, 311: 96-104. 10.1016/S0042-6822(03)00192-2

Cha SH, Choi EJ, Park JH, Yoon SR, Kwon JH, Yoon KJ, Song JY: Phylogenetic characterization of classical swine fever viruses isolated in Korea between 1988 and 2003. Virus Res 2007, 126: 256-261. 10.1016/j.virusres.2007.01.017

Tu C, Lu Z, Li H, Yu X, Liu X, Li Y, Zhang H, Yin Z: Phylogenetic comparison of classical swine fever virus in China. Virus Res 2001, 81: 29-37. 10.1016/S0168-1702(01)00366-5

Chen N, Hu H, Zhang Z, Shuai J, Jiang L, Fang W: Genetic diversity of the envelope glycoprotein E2 of classical swine fever virus: recent isolates branched away from historical and vaccine strains. Vet Microbiol 2008, 127: 286-299. 10.1016/j.vetmic.2007.09.009

Wang Z, Nie Y, Wang P, Ding M, Deng H: Characterization of classical swine fever virus entry by using pseudotyped viruses: E1 and E2 are sufficient to mediate viral entry. Virology 2004, 330: 332-341. 10.1016/j.virol.2004.09.023

Risatti GR, Borca MV, Kutish GF, Lu Z, Holinka LG, French RA, Tulman ER, Rock DL: The E2 glycoprotein of classical swine fever virus is a virulence determinant in swine. J Virol 2005, 79: 3787-3796. 10.1128/JVI.79.6.3787-3796.2005

Risatti GR, Holinka LG, Fernandez Sainz I, Carrillo C, Kutish GF, Lu Z, Zhu J, Rock DL, Borca MV: Mutations in the carboxyl terminal region of E2 glycoprotein of classical swine fever virus are responsible for viral attenuation in swine. Virology 2007, 364: 371-382. 10.1016/j.virol.2007.02.025

Bouma A, de Smit AJ, de Kluijver EP, Terpstra C, Moormann RJ: Efficacy and stability of a subunit vaccine based on glycoprotein E2 of classical swine fever virus. Vet Microbiol 1999, 66: 101-114. 10.1016/S0378-1135(99)00003-6

van Rijn PA, Bossers A, Wensvoort G, Moormann RJ: Classical swine fever virus (CSFV) envelope glycoprotein E2 containing one structural antigenic unit protects pigs from lethal CSFV challenge. J Gen Virol 1996,77(Pt 11):2737-2745. 10.1099/0022-1317-77-11-2737

van Rijn PA, van Gennip HG, de Meijer EJ, Moormann RJ: Epitope mapping of envelope glycoprotein E1 of hog cholera virus strain Brescia. J Gen Virol 1993,74(Pt 10):2053-2060. 10.1099/0022-1317-74-10-2053

Lin M, Lin F, Mallory M, Clavijo A: Deletions of structural glycoprotein E2 of classical swine fever virus strain alfort/187 resolve a linear epitope of monoclonal antibody WH303 and the minimal N-terminal domain essential for binding immunoglobulin G antibodies of a pig hyperimmune serum. J Virol 2000, 74: 11619-11625. 10.1128/JVI.74.24.11619-11625.2000

Lowings JP, Paton DJ, Sands JJ, De Mia GM, Rutili D: Classical swine fever: genetic detection and analysis of differences between virus isolates. J Gen Virol 1994,75(Pt 12):3461-3468. 10.1099/0022-1317-75-12-3461

van Rijn PA: A common neutralizing epitope on envelope glycoprotein E2 of different pestiviruses: implications for improvement of vaccines and diagnostics for classical swine fever (CSF)? Vet Microbiol 2007, 125: 150-156. 10.1016/j.vetmic.2007.05.001

Chang CY, Huang CC, Lin YJ, Deng MC, Tsai CH, Chang WM, Wang FI: Identification of antigen-specific residues on E2 glycoprotein of classical swine fever virus. Virus Res 2010, 152: 65-72. 10.1016/j.virusres.2010.06.005

Clavijo A, Lin M, Riva J, Mallory M, Lin F, Zhou EM: Development of a competitive ELISA using a truncated E2 recombinant protein as antigen for detection of antibodies to classical swine fever virus. Res Vet Sci 2001, 70: 1-7. 10.1053/rvsc.2000.0434

Lin M, Trottier E, Mallory M: Enzyme-linked immunosorbent assay based on a chimeric antigen bearing antigenic regions of structural proteins Erns and E2 for serodiagnosis of classical swine fever virus infection. Clin Diagn Lab Immunol 2005, 12: 877-881.

Plotkin JB, Dushoff J: Codon bias and frequency-dependent selection on the hemagglutinin epitopes of influenza A virus. Proc Natl Acad Sci USA 2003, 100: 7152-7157. 10.1073/pnas.1132114100

Li J, Wang Y, Liang Y, Ni B, Wan Y, Liao Z, Chan KH, Yuen KY, Fu X, Shang X, et al.: Fine antigenic variation within H5N1 influenza virus hemagglutinin's antigenic sites defined by yeast cell surface display. Eur J Immunol 2009, 39: 3498-3510. 10.1002/eji.200939532

Lipsitch M, O'Hagan JJ: Patterns of antigenic diversity and the mechanisms that maintain them. J R Soc Interface 2007, 4: 787-802. 10.1098/rsif.2007.0229