• Asian-Australasian Journal of Animal Sciences
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• v.25 no.8
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• pp.1089-1095
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• 2012

Neonatal Fc receptor (FcRn) gene encodes a receptor that binds the Fc region of monomeric immunoglobulin G (IgG) and is responsible for IgG transport and stabilization. In this report, the 8,900 bp porcine FcRn genomic DNA structure was identified and putative FcRn protein included 356 amino acids. Alignment and phylogenetic analysis of the porcine FcRn amino acid sequences with their homologies of other species showed high identity. Tissues expression of FcRn mRNA was detected by real time quantitative polymerase chain reaction (Q-PCR), the results revealed FcRn expressed widely in ten analyzed tissues. One single nucleotide polymorphism (SNP) (HQ026019:g.8526 C>T) in exon6 region of porcine FcRn gene was demonstrated by DNA sequencing analysis. A further analysis of SNP genotypes associated with serum Classical Swine Fever Virus antibody (anti-CSFV) concentration was performed in three pig populations including Large White, Landrace and Songliao Black pig (a Chinese indigenous breed). Our results of statistical analysis showed that the SNP had a highly significant association with the level of anti-CSFV antibody (At d 20; At d 35) in serum (p = 0.008; p = 0.0001). Investigation of expression and polymorphisms of the porcine FcRn gene will help us in further understanding the molecular basis of the antibody regulation pathway in the porcine immune response. All these results indicate that FcRn gene might be regarded as a molecular marker for genetic selection of anti-CSFV antibody level in pig disease resistance breeding programmes.

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.2
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• pp.207-213
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• 2014

The structural proteins of classical swine fever virus (CSFV) consist of nucleocapsid protein C and envelope glycoprotein $E^{rns}$ (E0), E1 and E2. Among them, E2, the most immunogenic of the CSFV glycoproteins, induces a protective immune response in swine. In this study, to determine the optimal expression conditions of glycoprotein E2 using baculovirus system, we investigated the influence of insect cells and media to the expression of recombinant E2. Recombinant virus containing glycoprotein E2 coding gene was constructed with bApGOZA DNA. Expression of the glycoprotein E2 was analyzed by SDS-PAGE and Western blot analysis using anti-CSFV E2 monoclonal antibodies. Expression of glycoprotein E2 in Sf21 cells was first observed after 3 days and reached a maximum on the 5th day after infection. Furthermore, the highest levels of glycoprotein E2 expression were observed at multiplicity of infection (MOI) of 5. When three different insect cell lines (Sf21, High-Five and Se301) were tested, High-Five cells showed the highest production. In addition, four different serum-free and serum-supplemented media, respectively, were tested for the expression of glycoprotein E2 and the budded virus (BV) titers. As a result, serum-supplemented medium provided the best conditions for protein production and the BV yield.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.537-546
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• 2015

Classical swine fever (CSF) is a highly contagious disease of pigs caused by CSF virus (CSFV). E2 is the major viral envelope protein of immune dominance that induces neutralizing antibodies and confers protection against CSFV infection. The B/C domains of E2 are variable among CSFV isolates, which could affect immunogenicity and binding to antibodies. We attempted to characterize the epitope recognized by a monoclonal antibody 2B6 (mAb-2B6) raised against the E2 B/C domains of the vaccine C-strain and to examine if mutations in the epitope region would affect antibody binding and viral neutralization. The epitope specific for mAb-2B6 recognition is linear, spanning five residues ⁷⁷⁴DGXNP⁷⁷⁸ in the B/C domains. The residue N777 is indispensable for the specificity. The epitope exists only in group 1 strains, but not in those of group 2. The recombinant viruses containing individual mutations on the epitope region lost the reactivity to mAb-2B6. The mutant virus RecC-N777S had low replication potential, about 10-fold decrease in the yield of progeny virus particles, whereas the mutant virus RecC-P778A reverted to proline upon continuous passaging. The mutations on the mAb-2B6 epitope region did not affect neutralization by anti-C-strain polyclonal sera from pigs. Deletion from aa774 covering the mAb-2B6 epitope, but not that from aa781, also affected binding with the polyclonal antibodies from vaccinated pigs, although the major binding region for the vaccinated antibodies is aa690-773.