Submitted to: International Geminivirus Symposium
Publication Type: Abstract Only
Publication Acceptance Date: May 11, 2007
Publication Date: May 20, 2007
Citation: Cheung, A.K. 2007. Exploring the genetic basis for porcine circovirus pathogenicity [abstract]. 5th International Geminivirus Symposium and 3rd International ssDNA Comparative Virology Workshop. Paper No. Py4-KN. p. 122. Technical Abstract: Porcine circoviruses are members of the Circovirus genus within the Circoviridae family. Association of porcine circovirus type 2 (PCV2) with post-weaning multisystemic wasting syndrome (PMWS) was first reported in western Canada in 1996. Shortly thereafter the disease was recognized in Europe. Subsequently, PCV2 has been detected in many parts of the world and PMWS has become an economically important disease among swine producing countries. PMWS is a multifactor disease and not all pigs exposed to PCV2 exhibit clinical symptoms. Many researchers have argued that PCV2 alone is not sufficient to induce a clinical disease and that a co-factor is required for full expression of PMWS. Factors that have been shown to influence the expression of clinical PMWS include co-infection with other pathogens, immune status of the infected animals and the genetic make-up of the hosts. In the decade following the initial epizootic PMWS in Canada in the mid-1990s, no major outbreaks of PMWS have been reported in North America. However, during this time, PMWS has become a devastating disease in many European and Asian countries. Attempts made to reproduce clinical PMWS with the "North American" or "European" PCV2 isolates have met with limited success. Interestingly, severe PMWS re-emerged among many swine herds of Canada and the United States, in late 2004 and in late 2005, respectively. On the affected farms, mortality levels among the infected herds were significantly higher than the historical baselines. To shed new light on the genetic basis for PCV2 pathogenicity, field observations correlated with laboratory findings will be presented in this discussion.