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Identification of Critical Amino Acid in Capsid Protein of PCV2

by 5m Editor
13 September 2011, at 12:00am

The amino acid, alanine, at position 59 in the capsid protein of PCV2a (CL, LG and JF2) strains is a critical amino acid, which determines one neutralising epitope of those strains, according to researchers at the Chinese Academy of Agricultural Sciences.

Porcine circovirus type 2 (PCV2) is associated with post-weaning multisystemic wasting syndrome (PMWS) in pigs, explain Li P. Huang and colleagues at the Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences in their paper published in August in BMC Microbiology. They continue that currently, there is considerable interest in the immunology of PCV2; in particular, the immunological properties of the capsid protein. This protein is involved in PCV2 immunogenicity and is a potential target for vaccine development. In this study, we identified one critical amino acid that determines a conformational neutralizing epitope in the capsid protein of PCV2.

One monoclonal antibody (mAb; 8E4), against the capsid protein of PCV2, was generated and characterised in this study. 8E4 reacted with the genotype PCV2a (CL, LG and JF2) strains but not PCV2b (YJ, SH and JF) strains by an immunoperoxidase mono-layer assay (IPMA) and a capture ELISA. Furthermore, the mAb had the capacity to neutralise PCV2a (CL, LG and JF2) strains but not PCV2b (YJ, SH and JF) strains. One critical amino acid that determined a conformational neutralising epitope was identified using mAb 8E4 and PCV2 infectious clone technique. Amino acid residues 47-72 in the capsid protein of PCV2a/CL were replaced with the corresponding region of PCV2b/YJ, and the reactivity of mAb 8E4 was lost. Further experiments demonstrated that one amino acid substitution, the alanine for arginine at position 59 (A59R) in the capsid protein of PCV2a (CL, LG and JF2) strains, inhibited completely the immunoreactivity of three PCV2a strains with mAb 8E4.

Huang and co-authors concluded that the alanine at position 59 in the capsid protein of PCV2a (CL, LG and JF2) strains is a critical amino acid, which determines one neutralising epitope of PCV2a (CL, LG and JF2) strains.

They add that their study provides valuable information for further in-depth mapping of the conformational neutralising epitope, understanding antigenic difference among PCV2 strains, and development of a useful vaccine for control of PCV2-associated disease.

Reference

Huang L.P., Y.H. Lu, Y.W. Wei, L.J. Guo and C.M. Liu. 2011. Identification of one critical amino acid that determines a conformational neutralizing epitope in the capsid protein of porcine circovirus type 2. BMC Microbiology 2011, 11:188. doi:10.1186/1471-2180-11-188

Further Reading

- You can view the full report by clicking here.


Further Reading

- Find out more information on PMWS by clicking here.


September 2011