Back to Virology

Murine cells used to produce biopharmaceutical products are known to harbor infectious retroviruses, some of which are also capable of infecting human cells and which, therefore, represent a safety concern. Other rodent cells (e.g., rat myeloma cell lines and hybridomas) also express retroviruses and the absence of infectious retrovirus must be demonstrated. Chinese hamster ovary (CHO) cell lines are known to harbor high levels of defective non-infectious retroviruses. Nevertheless, the absence of infectious retrovirus must be demonstrated by sensitive infectivity assays. Nonhuman primate and human cell lines should be examined for the presence of retroviruses by using various methods. Primate cells should be screened for the presence of primate retroviruses. In general, retroviruses are not readily detectable by cytopathic effect (CPE). Through their capacity to integrate into the host cellular genome in a proviral form, retroviruses can be virtually undetectable by standard in vitro viral assays that are based on cytopathology. Therefore, a number of assays have been developed that use unique properties of retroviruses to aid in their detection.

Retrovirology services include:

• In vitro testing for retroviruses: cocultivation & amplification assays
• Infectivity assays for retroviruses: plaque & focus assays
• Reverse transcriptase assays
• Electron microscopy
• Soft agarose in vitro tumorigenicity assays