Viruses and renal carcinoma of Rana pipiens: IX. The influence of temperature and host cell on replication of frog polyhedral cytoplasmic deoxyribovirus (PCDV)

Abstract

PCDV replication was studied over the temperature range 8°–33° in cells originating from warm- and cold-blooded vertebrates of three classes: fish, mammals, and birds. These cells were fathead minnow (FHM), baby hamster kidney (BHK), and chicken embryo (CEF). No significant virus replication occurred in any cell type at either 8° or 10°, but at 12° replication occurred in all cell types used. However, yields of PCDV and rate of production at 12° were greater in cells from cold-blooded than from warm-blooded vertebrates (FHM > BHK > CEF). Furthermore, the viral latent period at 12° was shorter in FHM cells (12–24 hours) than in either BHK (2–3 days) or CEF cells (3–4 days). As the temperature was raised from 12 to 30 or 31°, the viral latent period decreased, the rate of multiplication increased, and high titers of infectious virus were obtained over a broad temperature range in all cells. At 30° to 31°, there was little difference in the latent periods (FHM cells, 3–4 hours; BHK cells, 4–6 hours) or in the rates of PCDV replication in cells originating from poikilotherms or homeotherms. Irrespective of cell type, both yield and rate of PCDV replication were reduced at 32°. Infectious progeny virus was not made in any cell type at 33°, but virus-specific macromolecules were formed at this temperature. Data from temperature shift experiments (33.5° → 24°) suggested that a temperature-sensitive event occurred late in the PCDV replication cycle, possibly at assembly of viral components. These results indicate that yields of PCDV and rate of replication are regulated by the host cell, but the permissive temperature zone is controlled by viral genes.