Typing of porcine circovirus in clinical specimens by multiplex PCR

A multiplex PCR assay was developed to detect and differentiate between the porcine circovirus (PCV) infecting persistently the PK 15 cell line (PCV t ype I) and the PCV associated with postweaning multisystemic wasting syndro me (PMWS) (PCV type II). DNA products with unique sizes characteristic of e ach type of PCV were obtained. Sequencing of these products demonstrated th at the nucleotide sequences were type-specific. Tissue samples from a total of 42 field cases from Quebec were studied, among which 41 were collected in 1997-1998 and one which had been previously collected in 1994. These 42 cases found previously to be PCV-positive by PCR were tested in the present study by a multiplex PCR assay to determine the type of PCV in each case. From these 42 field cases, 40 cases were PCV type II-positive, one case was PCV type I-positive and one case was positive for both PCV types I and II. PCV type II was identified in typical PMWS held cases, but also in field c ases submitted for various clinical histories, some of which were not sugge stive of PMWS. In the field case where PCV type I was detected, there was n o clinical evidence nor histological lesions suggestive of PMWS. The demons tration of PCV type II in a total of 41/42 field cases in the present study suggests that PCV type II may be the main type of PCV circulating in pigs. Furthermore the detection of PCV type II in a field case dating back to 19 94 indicates that this PCV type was circulating in pigs in Quebec several y ears before the report of clinical PMWS in this province. (C) 1999 Elsevier Science B.V. All rights reserved.