title: Effects of ribavirin on the replication and genetic stability of porcine reproductive and respiratory syndrome virus.
abstract: BACKGROUND
  Although modified live virus (MLV) vaccines are commonly used for porcine reproductive and respiratory syndrome virus (PRRSV) control, there have been safety concerns due to the quick reversion of MLV to virulence during replication in pigs. Previous studies have demonstrated that mutant viruses emerged from lethal mutagenesis driven by antiviral mutagens and that those viruses had higher genetic stability compared to their parental strains because they acquired resistance to random mutation. Thus, this strategy was explored to stabilize the PRRSV genome in the current study.
  
  
  RESULTS
  Four antiviral mutagens (ribavirin, 5-fluorouracil, 5-azacytidine, and amiloride) were evaluated for their antiviral effects against VR2332, a prototype of type 2 PRRSV. Among the mutagens, ribavirin and 5-fluorouracil had significant antiviral effects against VR2332. Consequently, VR2332 was serially passaged in MARC-145 cells in the presence of ribavirin at several concentrations to facilitate the emergence of ribavirin-resistant mutants. Two ribavirin-resistant mutants, RVRp13 and RVRp22, emerged from serial passages in the presence of 0.1 and 0.2 mM ribavirin, respectively. The genetic stability of these resistant mutants was evaluated in MARC-145 cells and compared with VR2332. As expected, the ribavirin-resistant mutants exhibited higher genetic stability compared to their parental virus.
  
  
  CONCLUSIONS
  In summary, ribavirin and 5-fluorouracil effectively suppressed PRRSV replication in MARC-145 cells. However, ribavirin-resistant mutants emerged when treated with low concentrations (≤0.2 mM) of ribavirin, and those mutants were genetically more stable during serial passages in cell culture.
authors.affiliation: College of Veterinary Medicine, Chonbuk National University Jeonju, Korea, 664-14 Deokjin-Dong 1 Ga, Jeonju, Jeonbuk, 561-756, Republic of Korea. aminak@jbnu.ac.kr.
authors.forename: Amina
authors.initials: A
authors.lastname: Khatun
authors.affiliation: College of Veterinary Medicine, Chonbuk National University Jeonju, Korea, 664-14 Deokjin-Dong 1 Ga, Jeonju, Jeonbuk, 561-756, Republic of Korea. drnadurose@gmail.com.
authors.forename: Nadeem
authors.initials: N
authors.lastname: Shabir
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA. kyoon@iastate.edu.
authors.forename: Kyoung-Jin
authors.initials: KJ
authors.lastname: Yoon
authors.affiliation: College of Veterinary Medicine, Chonbuk National University Jeonju, Korea, 664-14 Deokjin-Dong 1 Ga, Jeonju, Jeonbuk, 561-756, Republic of Korea. kwi0621@jbnu.ac.kr.
authors.forename: Won-Il
authors.initials: WI
authors.lastname: Kim
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D001374:Azacitidine / Q000494:pharmacology; D002460:Cell Line; D002522:Chlorocebus aethiops; D005472:Fluorouracil / Q000494:pharmacology; D016679:Genome, Viral / Q000187:drug effects; D016296:Mutagenesis / Q000187:drug effects*; D009153:Mutagens / Q000494:pharmacology; D019316:Porcine respiratory and reproductive syndrome virus / Q000187:drug effects* / Q000502:physiology; D012254:Ribavirin / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D009153:Mutagens; D012254:Ribavirin; D000584:Amiloride; D001374:Azacitidine; D005472:Fluorouracil