Brazilian Journal of Microbiology Brazilian Journal of Microbiology
Braz J Microbiol 2018;49:351-7 - Vol. 49 Num.2 DOI: 10.1016/j.bjm.2017.08.007
Veterinary Microbiology
Structure analysis of capsid protein of Porcine circovirus type 2 from pigs with systemic disease
Danielle Gavaa, Vitor Hugo Balasco Serrãob, Lana Teixeira Fernandesc, Mauricio Egídio Cantãoa, Janice Reis Ciacci-Zanellaa, Nelson Morésa, Rejane Schaefera,,
a Embrapa Suínos e Aves, Concórdia, SC, Brazil
b Universidade de São Paulo – USP, Instituto de Física de São Carlos, São Carlos, 13566-590, SP, Brazil
c Centro de Diagnóstico de Sanidade Animal (CEDISA), Concórdia, SC, Brazil
Received 02 March 2017, Accepted 01 August 2017
Abstract

Economic losses with high mortality rate associated with Porcine circovirus type 2 (PCV2) is reported worldwide. PCV2 commercial vaccine was introduced in 2006 in U.S. and in 2008 in Brazil. Although PCV2 vaccines have been widely used, cases of PCV2 systemic disease have been reported in the last years. Eleven nursery or fattening pigs suffering from PCV2 systemic disease were selected from eight PCV2-vaccinated farms with historical records of PCV2 systemic disease in Southern Brazil. PCV2 genomes were amplified and sequenced from lymph node samples of selected pigs. The comparison among the ORF2 amino acid sequences of PCV2 isolates revealed three amino acid substitutions in the positions F57I, N178S and A190T, respectively. Using molecular modeling, a structural model for the capsid protein of PCV2 was built. Afterwards, the mutated residues positions were identified in the model. The structural analysis of the mutated residues showed that the external residue 190 is close to an important predicted region for antibodies recognition. Therefore, changes in the viral protein conformation might lead to an inefficient antibody binding and this could be a relevant mechanism underlying the recent vaccine failures observed in swine farms in Brazil.

Keywords
Porcine circovirus type 2 (PCV2), Capsid protein, Molecular modeling and antigenic epitope
Braz J Microbiol 2018;49:351-7 - Vol. 49 Num.2 DOI: 10.1016/j.bjm.2017.08.007
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