Growth curve of murine xenotropic leukemia virus-related virus grown in Chinese hamster ovary cells

BackgroundMurine 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.MethodsThe 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.ResultsThe 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.ConclusionBased 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.