Abstract
Yields of infectious pancreatic necrosis virus from fathead minnow cell cultures were maximal at 20 °C. The virus failed to replicate at 28 °C and neither virus-specific mRNA nor virus-specific polypeptides could be detected when infected cells were maintained at this temperature. Intrinsic thermolability of virus infectivity or inability to adsorb to cells at 28 °C could not account for the temperature-dependent block in virus morphogenesis. Analysis of infectious virus production and virus-specific polypeptide and RNA synthesis following shifts from the permissive (20 °C) to the non-permissive temperature (28 °C) at various times after infection indicated that multiple temperature-sensitive (ts) steps were involved in the inhibition of virus replication.