Distribution of antibodies against porcine circovirus type-2 (PCV2) in single site and multi-site farrow-to-finish farms in Brazil Priscilla F. Gerber a , Grazielle C.F. Galinari a , Marcos X. Silva b , Fábia S. Campos a , Adrienny C.T. Reis c , Zélia I.P. Lobato a, * a Laboratório de Pesquisa em Virologia Animal, Departamento de Medicina Veterinária Preventiva, Universidade Federal de Minas Gerais, Minas Gerais, Brazil b Genética e Melhoramento, Departamento de Zootecnia, Universidade Federal de Minas Gerais, Minas Gerais, Brazil c IPEVE, Instituto de Pesquisas Veterinárias Especializadas, Belo Horizonte, Minas Gerais, Brazil article info Article history: Accepted 20 April 2009 Keywords: Pig Epidemiology Serology Immunoperoxidase monolayer assay Porcine circovirus type-2 Post-weaning multisystemic wasting syndrome abstract A comparative serologic study was performed in seven single site (SS) farrow-to-finish farms and four multi-site (MS) farrow-to-finish farms, with or without post-weaning multisystemic wasting syndrome (PMWS). In each farm, 30 blood samples were collected for each category of the production cycle: sows, farrowing crate, nursery, grower pigs, and finishing pigs. Sera were evaluated for the presence of antibod- ies to porcine circovirus type-2 (PCV2) via immunoperoxidase monolayer assay. Serologic profiles for PCV2 were different between SS and MS farms. Seroconversion following the decline in maternal antibod- ies occurred at a later stage on SS farms (grower pigs) than MS farms (nursery pigs). MS farms tended to have lower antibody titers than SS farms in the categories of sow, piglet, and nursery, while higher anti- body titers were found in grower pigs. Characterization of serologic profiles for different farms may pro- vide important information for the adoption of vaccination programs. Ó 2009 Elsevier Ltd. All rights reserved. Porcine circovirus type-2 (PCV2) is the causative agent of post- weaning multisystemic wasting syndrome (PMWS), which is ubiq- uitous in the swine population, resulting in great impacts on the global swine industry, mainly due to increases in mortality and the production of non-marketable pigs (López-Soria et al., 2005). Although PCV2 serology has no diagnostic value, this bioindica- tor can be utilized to determine when the infection occurs in the herd through analysis of longitudinal or transversal studies (Opri- essnig et al., 2007), due to the high prevalence of infection in clin- ically healthy animals (Carasova et al., 2007). Analysis of the serological profile may increase knowledge of viral circulation and may be useful for the implementation of vaccination strategies and effective control measures according to the characteristics of an individual herd. This work investigates serological profiles against PCV2 in sin- gle site (SS) or multi-site (MS) farrow-to-finish farms, with or with- out PMWS. Serology against PCV2 was studied in seven SS farrow-to-finish farms (F1–F7) and four MS farrow-to-finish farms (F8–F11) with or without clinical signs of PMWS, according to criteria described by Quintana et al. (2001). A herd was considered positive for PMWS when at least one of five pigs per herd presented these character- istics simultaneously: (1) clinical signs, such as wasting, (2) mod- erate to severe lymphocyte depletion and granulomatous inflammation of lymphoid tissues, and (3) the presence of moder- ate to high amount of PCV2 in these lesions. All sows on the farms were routinely vaccinated against porcine parvovirus, erysipelas and colibacilosis; some farms also vaccinated sows against Clos- tridium perfringens and/or mycoplasma. None of the farms vacci- nated sow or pigs against PCV2. In the SS group, F1 and F7 had no history of PMWS, while F6 had history of PMWS 1.5 years prior to this investigation, but had no clinical signs during the present study. The other farms were clas- sified as PMWS positive and the clinical signs occurred in pigs at 8 to 14 weeks of age. In the SS farms, piglets were arranged in far- rowing crates from birth until weaning at 3 weeks of age, then moved into nursery, into the grower areas (8 weeks), and then into the finisher areas (14 weeks) at the same site. The number of sows per farm ranged from 450 to 2500. The MS farms were all PMWS positive, except for F9. In these farms, pigs born in different sow-farms (site 1) were moved to nurseries at a weaning age. In the nursery phase (site 2), nursery farms were multi-origin by site. In the grower phase (site 3), the fattening units were filled with pigs from these nurseries at 15 weeks of age. The clinical signs occurred in pigs at 13 to 17 weeks of age. The number of sows per farm ranged from 5400 to 7000. 0034-5288/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.rvsc.2009.04.013 * Corresponding author. Tel.: +55 31 34092101; fax: +55 31 34092080. E-mail address: ziplobat@vet.ufmg.br (Z.I.P. Lobato). Research in Veterinary Science 87 (2009) 488–491 Contents lists available at ScienceDirect Research in Veterinary Science journal homepage: www.elsevier.com/locate/rvsc