Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2006
Publication Date: 5/1/2007
Citation: Cheung, A.K., Lager, K.M., Kohutyuk, O.I., Vincent, A.L., Henry, S.C., Baker, R.B., Rowland, R.R., Dunham, A.G. 2007. Detection of two porcine circovirus type 2 genotypic groups in United States swine herds. Archives of Virology. 152(5):1035-1044. Interpretive Summary: Porcine circovirus type 2 (PCV2) is a newly emerged viral pathogen of swine. While clinical signs of disease and postmortem lesions induced by PCV2 are known, there is little information on the temporal pathogenesis and epidemiology of the virus. Previous phylogenetic analyses have shown that PCV2 can be separated into two subtype viruses: the "North American" PCV-2a and the "European" PCV-2b. Whereas only PCV-2a subtype viruses have been reported in North America, both PCV-2a and PCV-2b subtype viruses have been reported in Europe and in Asia. This is the first report describing the presence of PCV-2b viruses in swine herds of North Carolina, Kansas, and Iowa affected with the newly coined "severe form of PMWS." The significance of the PCV-2b viruses circulating in U.S. swine remains to be elucidated.
Technical Abstract: In late 2005, sporadic cases of an acute onset disease of high mortality were observed in 10- to 16-week-old growing pigs among several swine herds of the United States. Tissues from the affected pigs in Kansas, Iowa, and North Carolina were examined and porcine circovirus type 2 (PCV2) was detected consistently among these tissues. Phylogenetically, PCV2 can be divided into two major genotypic groups, PCV2-group 1 and PCV2-group 2. Whereas PCV2-group 1 isolates were detected in all the diseased animals, only two of the diseased animals harbored PCV2-group 2 isolates. This observation is important because PCV2-group 1 isolates had never been reported in the United States before (GenBank as of May 16, 2006) and they are closely related to the PCV2-group 1 isolates that have been described in Europe and Asia, previously. Our analysis revealed that each genotypic group contains a distinct stretch of nucleotide or amino acid sequence that may serve as a signature motif for PCV2-group 1 or PCV2-group 2 isolates.