This Article Full Text Full Text (PDF) Other Versions of this Article: JCM.01927-07v1 46/5/1758    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Kim, W.-I. Articles by Yoon, K.-J. PubMed PubMed Citation Articles by Kim, W.-I. Articles by Yoon, K.-J.

 Previous Article  |  Next Article 

Journal of Clinical Microbiology, May 2008, p. 1758-1768, Vol. 46, No. 5
0095-1137/08/$08.00+0     doi:10.1128/JCM.01927-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Different Biological Characteristics of Wild-Type Porcine Reproductive and Respiratory Syndrome Viruses and Vaccine Viruses and Identification of the Corresponding Genetic Determinants

Won-Il Kim, Jae-Jo Kim, Sang-Ho Cha, and Kyoung-Jin Yoon^*

Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa 50011

Received 28 September 2007/ Returned for modification 14 November 2007/ Accepted 4 February 2008

Two attenuated vaccines, Ingelvac PRRS MLV and Ingelvac PRRS ATP, derived from VR2332 and JA142, respectively, have been used to control porcine reproductive and respiratory syndrome (PRRS) virus. However, there have been several field reports concerning the reversion of the vaccine virus to virulence. Furthermore, viruses genetically indistinguishable from the vaccines and wild-type parental viruses have been detected in clinical PRRS cases, raising the need for a better differential tool. As the vaccine viruses replicated better and produced bigger plaques in MARC-145 cells than did the wild-type parental strains, the following study was conducted to determine if the growth difference in MARC-145 cells can be utilized to differentiate a vaccine-like virus (VLV) from a wild-type virus and to identify genetic markers corresponding to such phenotype of the vaccine viruses. The relatedness of 83 field isolates collected between 1996 and 2005 to VR2332 and JA142 was classified genetically and antigenically. Thirteen of 25 VR2332-related viruses and 9 of 10 JA142-related viruses were determined as VLVs, since those viruses produced plaques similar to those by the vaccine viruses. Four unique amino acids each were identified throughout structural genes for MLV and ATP. Among those, F¹⁰ in open reading frame 2 (ORF2) of MLV and E⁸⁵ and Y¹⁶⁵ in ORF3 of ATP were stable during pig passages. When the sequences unique for MLV were incorporated into an infectious clone constructed based on VR2332, the virus growth and resultant plaque size in MARC-145 cells were increased, suggesting that these sequences can be used as genetic markers for VLVs.

Published ahead of print on 13 February 2008.

Present address: National Veterinary Research and Quarantine Service, Korean Ministry of Agriculture and Forestry, Anyang-si, Kyunggi-do, South Korea.