RESUMEN
Porcine circovirus-2 (PCV-2) is the main agent related to post-weaning multisystemic wasting syndrome (PMWS) and it is also associated with other syndromes affecting pigs. Not all pigs infected with PCV-2 will develop PMWS and the incidence of PMWS is higher when coinfecting viral and bacterial pathogens are present. In this study, PCV-2 viral loads were evaluated in the tissues of animals with and without PMWS in order to investigate the relationship between viral load and microscopical lesions. Lymph nodes had the highest average viral load, but there was no significant difference between lesion severity and the viral load in these structures. There was no significant difference between the average viral load in inguinal lymph nodes of animals with and without PMWS. However, samples from pigs with PMWS had more severe lesions compared with samples from non-PMWS animals. These findings suggest that other infectious and non-infectious cofactors may be important in the pathogenesis of PMWS.
Asunto(s)
Circovirus/fisiología , Síndrome Multisistémico de Emaciación Posdestete Porcino/patología , Animales , Circovirus/aislamiento & purificación , ADN Viral/análisis , Interacciones Huésped-Patógeno , Ganglios Linfáticos/patología , Ganglios Linfáticos/virología , Síndrome Multisistémico de Emaciación Posdestete Porcino/virología , Porcinos , Carga ViralRESUMEN
Porcine circovirus 2 (PCV2) is the major causative agent of postweaning multisystemic wasting syndrome (PMWS) and is associated with different syndromes affecting pigs. The PCV2 genome has three main open reading frames (ORFs) among which the ORF2 encodes the capsid protein. In this study, the ORF2 nucleotide sequences of 30 Brazilian isolates were analyzed. The sequences were compared to other GenBank sequences using phylogenic and phylogeographic approaches. Our results show high sequence variability in Brazil, since, in this work, the Brazilian isolates were classified into subgroup 1AB, 2D and 2, which reveals that the virus was introduced in Brazil more than once. On the other hand, most of Brazilian isolates seem to be derived from only one introduction. According to the data from the Pig Breeders' Association, the multiple introductions of the virus probably occurred through the import of animals with the asymptomatic form of the virus or through the import of contaminated semen. The results point to the necessity of implementing programs aimed at selecting sows in order to avoid the import of animals infected by Group 1 PCV2.