Interferon-mediated inhibition of production of Gazdar murine sarcoma virus, a retrovirus lacking env proteins and containing an uncleaved gag precursor

Abstract

HTG2 cells are murine sarcoma virus-transformed hamster cells. These cells continuously produce Gazdar sarcoma virus particles which are devoid of viral envelope proteins and which contain the uncleaved gag precursor polyprotein, Pr65, as their major protein constituent. Human interferon-α elicited an antiviral response in these cells as shown by the inhibition of replication of vesicular stomatitis virus in interferon-treated cells. Extracellular production of the retroviral particles by these cells was also inhibited by interferon in a dose-dependent manner and this inhibition was abolished by a specific antiserum to interferon. The intracellular level of Pr65 was not lowered in the interferon-treated cells, indicating that inhibition of viral protein synthesis was not responsible for inhibition of virus production. The present study suggests that interferon-mediated inhibition of retrovirus production, in general, is not a consequence of either a defective interaction between viral nucleoprotein cores and viral envelope proteins or a defect in the proteolytic processing of the gag polyprotein, since neither of these processes occurs during the morphogenesis of Gazdar particles and their production is nonetheless inhibited by interferon.