title: Establishment of persistent infection with foot-and-mouth disease virus in BHK-21 cells.
abstract: BACKGROUND
  Foot-and-mouth disease virus (FMDV) is able to cause persistent infection in ruminants besides acute infection and disease. Since the mechanisms of viral persistence and the determining factors are still unknown, in vitro systems help explore and reveal mechanisms of persistence in vivo by providing useful models for the study of RNA genome mutations and evolution. Ammonium chloride, a lysosomotropic agent that raises intralysosomal pH, reduces the yield of FMDV during infection of BHK-21 cells.
  
  
  RESULTS
  The persistent infection with FMDV serotype O in BHK-21 cells was selected and established readily after treatment of ammonium chloride that acts primarily on the cells. Intact virions were observed located inside the endosomes. Viral genome RNAs and specific proteins were detected in the persistent cells to validate the establishment of viral persistence. Infection of the persistent viruses could not form plaques in host cells but virulence was enhanced. Basing on analysis and comparison of cDNA sequences of resident viruses and wild type viruses, 15 amine acid mutations were found, all of which were located in nonstructural proteins rather than in structural proteins.
  
  
  CONCLUSIONS
  Therefore, persistent infection of cell cultures with FMDV is successfully established with some distinctive features. It would be worthwhile to further investigate the mechanisms of viral persistence.
authors.affiliation: State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Huang
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Fang
authors.forename: Congyi
authors.initials: C
authors.lastname: Zheng
mesh_terms: D000643:Ammonium Chloride / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D029544:Foot-and-Mouth Disease Virus / Q000254:growth & development*; D008247:Lysosomes / Q000737:chemistry / Q000648:ultrastructure / Q000821:virology; D008853:Microscopy; D012367:RNA, Viral / Q000032:analysis / Q000302:isolation & purification; D019562:Viral Load; D014764:Viral Proteins / Q000032:analysis; D014771:Virion / Q000648:ultrastructure; D014776:Virus Cultivation / Q000379:methods
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins; D000643:Ammonium Chloride