Frog Virus 3 Replication: Induction and Intracellular Distribution of Polypeptides in Infected Cells

Abstract

The synthesis of the polypeptides induced in frog virus 3-infected cells was analyzed by high-resolution sodium dodecyl sulfate-polyacrylamide gel electrophoresis of radiolabeled cell extracts. Purified frog virus 3 contained 22 polypeptides, with molecular weights in the range 9 x 103 to 114 x 103. All of the structural and an additional seven nonstructural polypeptides were detected in infected cell lysates. The following three classes of induced polypeptides (under temporal control) were observed in BHK cells: at 2 h, four a polypeptides; at 4 h, 13 18 polypeptides; and at 6 h, the remaining 12 y polypeptides. The total molecular weight of the infected cell-specific polypeptides (ICPs) was =1.5 x 106, which accounts for about 30% of the coding capacity of the viral genome. At least 10 of the induced polypeptides were phosphorylated, but none was glycosylated or sulfated. No evidence for posttranslation cleavage of polypeptides in pulse-chase and inhibition experiments was obtained. The synthesis of y polypeptides was not detected in the presence of the viral DNA replication inhibitors cytosine arabinoside and hydroxyurea, but halogenated nucleotides apparently had no effect. These results suggest that a and f polypeptides are "early" events and that detectable y polypeptide synthesis is dependent on the production of progeny viral DNA. The regulation of frog virus 3-induced polypeptide synthesis in infected BHK cells was examined by using inhibitors of protein and RNA synthesis and amino acid analogs. These experiments confirmed the existence of three sequentially synthesized, coordinately regulated classes of polypeptides, designated a, fl, and y. The requirements for the synthesis of each class were as

Experimental demonstration of the pathogenicity of a frog virus, Bohle iridovirus, for a fish species, barramundi Lates calcarifer

“…On the basls of size, pathogenicity and morphology, the iridovirus-like agent isolated from the catfish seemed to be more closely related to the sheatfish iridovirus and EHNV than it is to the other known piscine iridoviruses (Hedrick et al 1992). Similarly, Hengstberger et al (1993) reported that BIV had 12 structural proteins of similar molecular weight to those of FV3 described by Willis et al (1977) and Elliot & Kelly (1980). Similarities between FV3 and BIV were also found in restriction endonuclease (KpnI and HindIII) profiles of the viral DNA.…”

Epizootic haematopoietic necrosis virus: purification and classification

“…It is possible that the other smaller, more rapidly migrating proteins may also be present in purified viruses. Twenty-two proteins were detected in purified FV3 by Elliot & Kelly (1980). Overall, there appears to be little obvious similarity between the EHNV protein profile described here and that described by Elliot & Kelly (1980) for FV3.…”

“…Twenty-two proteins were detected in purified FV3 by Elliot & Kelly (1980). Overall, there appears to be little obvious similarity between the EHNV protein profile described here and that described by Elliot & Kelly (1980) for FV3. However, some similarities are evident when EHNV proteins are compared with those of FV3 analysed by Willis, Goorha, Miles & Granoff (1977).…”

“…Twenty-six viral specific proteins were detected in EHNV-infected cells. Elliot & Kelly (1980) and Willis etal. (1977) reported 29 and 35, respectively, in FV3-infected cells.…”

“…However, it should be noted that there is one biochemical feature which EHNV and FV3 have in common, namely a eapsid protein whose molecular weight is approximately 52kD. The MW of this protein in FV3 has been reported to be 55 kD (Elliot & Kelly 1980) and 48 kD (Tripier-Darcy et al 1982).…”