BackgroundThe porcine circovirus-associated disease (PCVAD) has been known since 1991 in Canada, but the first outbreak of PCVAD in Colombia was reported in 2007. In order to understand the molecular epidemiology of the disease and to establish the origin of the virus in the country, the study presented here intended to evaluate the presence of PCV2-associated systemic infection in piglets from different geographical regions over a period of 9-years (2002 -2010). The analysis included samples collected before, during and after outbreaks of PCVAD in pigs from Colombia. The PCV2 ORF2 from the positive samples was sequenced and used to determine the genotypes of the strains and to study the dynamic of these genotypes throughout the time.ResultsPCV2 DNA was detected in cases related to PCV2-associated systemic infection as well as in healthy pigs with a presumable persistent infection. The analysis of the ORF2 nucleotide full length sequence of twenty-three strains allowed to divide them into two groups: PCV2a and PCV2b. At the amino acid level the main variations in the sequence of the capsid protein were found in regions located within the immunoreactive areas.ConclusionsThe results of this study demonstrated for the first time, that the two subgroups: PCV2a and PCV2b have been circulating in swine from Colombia. In addition, the study showed that genotype PCV2b is present in Colombian pigs suffering from both clinical and presumable persistent infection and that the PCV2b genotype was present in the Colombian pig population even before recognition of the disease in the country and it became predominant through time.

Dinámica de la infección por el circovirus porcino tipo 2 y títulos de anticuerpos neutralizantes en las cerdas de reemplazo subclinicamente infectadas, y el efecto en sus camadasDinâmica da infeção pelo circovirus porcino tipo 2 e títulos de anticorpos neutralizantes em porcas nulíparas subclínicamente infectadas e efeito em sua leitegada Summary Background: porcine circovirus type 2 (PCV2) is associated with reproductive disease in newly populated herds and in replacement breeding stock from new sources and is almost exclusively reported in gilts. Objective: the main purpose of this study was to assess the dynamics of porcine circovirus type 2 infection and neutralizing antibodies in subclinically infected gilts and the effect on their piglets. Methods: the study was conducted with 40 gilts selected at random from four breeding herds. Blood samples, nasal and vaginal swabs were obtained from the gilts at arrival, acclimatization, farrowing, and one day after farrowing. Colostrum samples were collected immediately after parturition and one day after farrowing. Blood, nasal swab, or tissue samples were collected from four piglets prior to suckling. All serums were analyzed by virus neutralization test (VNT) to establish the presence of antibodies. All samples were subjected to SYBER Green real-time PCR assay to detect PCV2 DNA. Results: high levels of viremia and viral load of PCV2 in nasal and vaginal swabs were found in healthy gilts at arriving, confirming the introduction of infected animals into the farms. In addition, most gilts were positive for PCV2 DNA in serum, nasal and vaginal swabs at farrowing. PCV2 shedding was also observed in nasal and vaginal fluids and colostrum even in presence of serum neutralizing