Research of antigen and antibodies against Porcine Circovirus Type - 2 in pigs with and without postweaning multsystemic wasting syndrome from commercial farms of Minas Gerais State

Abstract

Porcine Circovirus Type 2 (PCV-2) is a non-enveloped circular single stranded DNA virus classified in the Circoviridae family related to post weaning multi systemic wasting syndrome (PMWS) in piglets. Immune-Histochemical (IHC) techniques are applied to detected PCV-2 antigen in the animal tissue injuries. Although, asymptomatic or sub clinic PCV-2 infected pigs could disseminate the virus in the flock. Serologic survey on apparently health pigs could suggest the virus ingression risk. In this work, antigens and antibodies against PCVS-2 in swine from commercial farms of seven and eight mesorregions of Minas Gerais State (MG) were investigated. 32 pigs with ages from five to eleven weeks which presented SMDS clinical signs were submitted to necropsy. PCV-2 antigens were investigated either from sacrificed pigs (Group I) and diagnosis demand samples (Group II) by IHC. 7,60% and more than 60% of the first and second groups, respectively, were positive for viral antigen. In both of them, intense marking of macrophages and histiocytes, especially in the lymph nodes and lung, evidenced antigens to CVS-2. In parallel, Immunoperoxidase Monolayer Assay (IPMA) was applied to antibody against PCV-2 screened in 955 pigs from 35 complete cycle commercial farms from same mesorregions. All pig flocks (100%) presented positive animals (confidence level 90% to 100%) and the frequency of reacting pigs varied 96.6% (confidence level 94,7% to 98,6%). PCV-2 antibody titers ranged 1:320 (medium) to 1:10.240 (high). The results suggest that 2.66% and 9% of pigs from Triângulo Mineiro and Zona da Mata regions respectively, would be able to develop clinical SMDS and that percentage reach 3.35% in the total serum.