title: Growth curve of murine xenotropic leukemia virus-related virus grown in Chinese hamster ovary cells.
abstract: BACKGROUND
  Murine xenotropic leukemia virus-related virus (XMulV) is used as a model virus in the evaluation of viral inactivation in Chinese hamster ovary (CHO) cell-derived pharmaceutical proteins. Mus dunni cells and mink lung cells are used to produce XMulV particles. In consideration of the characteristics of XMulV, we tried to propagate the viruses on CHO cells, a nonmurine cell line.
  
  
  METHODS
  The viruses were harvested from CHO cells from Day 2 to Day 7 postinfection, and reverse transcription-quantitative polymerase chain reaction was performed to quantify the viruses on different days. A cell-based infectivity assay was used to evaluate the XMulV titers.
  
  
  RESULTS
  The content of the XMulV virions began to increase on Day 5 and grew exponentially from Day 6 to Day 7 postinfection. The growth curve was a typical single-step growth curve. Titers of the viral stock harvested on Day 7 were assayed on PG-4 cells, and the titers were 8.78 ± 0.25 log10 PFU/mL.
  
  
  CONCLUSIONS
  Based on these data, we conclude that CHO cells could be a host cell line for XMulV particles. XMulV produced on Day 7 in CHO cells could be used at a laboratory scale for the evaluation of XMulV clearance in pharmaceutical proteins derived from CHO cells.
authors.affiliation: Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Ma
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Ming-Gang
authors.initials: MG
authors.lastname: Bi
authors.affiliation: Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China. Electronic address: cuixl2812@sina.com.
authors.forename: Xiao-Lan
authors.initials: XL
authors.lastname: Cui
mesh_terms: D000818:Animals; D016466:CHO Cells; D003412:Cricetulus; D005260:Female; D051379:Mice; D016133:Polymerase Chain Reaction; D048348:Reverse Transcription; D058008:Xenotropic murine leukemia virus-related virus / Q000254:growth & development*
keywords: CHO cell; growth charts; murine xenotropic leukemia virus-related virus; polymerase chain reaction; viral plaque assay