Supraoptimal Growth Temperatures Research Articles

Temperature-dependent interferon-sensitivity of foot-and-mouth disease virus.

Several strains of foot-and-mouth disease virus (FMDV), types O, A, and C, grown in primary or secondary calf kidney cell cultures had an interferon-sensitivity which varied with incubation temperature. Some wild-type strains growing optimally at 37° C showed an increased interferon-sensitivity at 28° C. Strain CL was more sensitive at both infra- and supraoptimal growth temperature. Temperature-sensitive mutants with optimal replication at 28° C were more sensitive at 37° C. Interferon-sensitivity moreover varied greatly among the virus strains tested even at optimal temperature. Results are interpreted by the hypothesis that the interferon-sensitivity depends on a virus specific product, presumably a protein, with a reduced optimal range of function (compared with virion formation) which acts as “anti-interferon”. Possible relationships with virulence of FMDV and temperature-sensitivity of viral proteins are discussed.

Acquired tolerance to elevated temperatures in a poikilothermic cell line (terrapene heart, TH-1)

TH-1 cells, derived from the turtle Terrapene carolina and routinely grown at 23 °C, were originally incapable of indefinite growth at 30 °C, or of any growth at 36 °C, designated high temperature sensitive (hts +). Following brief exposures (16 to 24 days) to 30 °C, two sublines eventually became capable of growth at 36 °C (hts −). Cells which where hts − grew at approximately equal rates at 23 °C, 30 °C and 36 °C, although cells grown at the warmer temperatures had larger surface areas. The attachment rates of both hts + and hts − cells to glass were similar and were directly proportional to temperature, over a temperature range of 15 °C to 36 °C. Hts − cells maintained at 23 °C subsequently developed morphological changes characterized by a change to more fusiform cell type and reduced cell contact inhibition. In sublines of hts − cells maintained at 30 °C and at 36 °C, a variety of nuclear aberrations also appeared. It is suggested that exposure to supra-optimal growth temperatures may have been responsible for the appearance of hts − cell sublines.