Koi herpesvirus represents a third cyprinid herpesvirus (CyHV-3) in the family Herpesviridae

The sequences of four complete genes were analysed in order to determine the relatedness of koi herpesvirus (KHV) to three fish viruses in the family Herpesviridae: carp pox herpesvirus (Cyprinid herpesvirus 1, CyHV-1), haematopoietic necrosis herpesvirus of goldfish (Cyprinid herpesvirus 2, CyHV-2) and channel catfish virus (Ictalurid herpesvirus 1, IcHV-1). The genes were predicted to encode a helicase, an intercapsomeric triplex protein, the DNA polymerase and the major capsid protein. The results showed that KHV is related closely to CyHV-1 and CyHV-2, and that the three cyprinid viruses are related, albeit more distantly, to IcHV-1. Twelve KHV isolates from four diverse geographical areas yielded identical sequences for a region of the DNA polymerase gene. These findings, with previously published morphological and biological data, indicate that KHV should join the group of related lower-vertebrate viruses in the family Herpesviridae under the formal designation Cyprinid herpesvirus 3 (CyHV-3).

Cytogenetic analysis of triploid renal carcinoma in Rana pipiens

To provide a cytogenetic marker for nuclear transplantation experiments, triploid Rana pipiens embryos were produced. These embryos were injected with Lucké tumor herpesvirus. The chromosome profile of a renal carcinoma that developed in one of these triploid embryos was compared to the chromosomal profiles of a naturally occurring diploid renal carcinoma and a diploid renal tumor maintained as serial anterior eye chamber allografts for over 7 yr. Examination of Ag-NOR-stained chromosome spreads from the putative triploid and naturally occurring putative diploid tumor revealed the expected results. The vast majority of the chromosome spreads, 54/57 (95%) and 6/7 (86%), respectively, displayed euploid chromosome and Ag-NOR profiles: 3N = 39 with three Ag-NORs at the secondary constrictions in the long arm of chromosome 10 (10q) and 2N = 26 with two Ag-NORs in 10q. Chromosome profiles from the long-term allografted tumor were highly aneuploid (82%) and, based on their Ag-NOR content, displayed variations in their 2N, 3N, and 4N numbers. These data indicate that the majority of recently transformed triploid Lucké tumor cells can provide donor nuclei suitable for the characterization of developmental potential.

Temperature-dependent dissociation of Lucké renal adenocarcinoma cells

Fragments of Lucké renal adenocarcinoma were subjected to dissociation by rapid shaking after exposure to a divalent cation-free electrolyte solution, with or without 5 X 10(-4) M ethylenediaminetetraacetate (EDTA), at 7 degrees C and 28 degrees C. More cells detached at 28 degrees C than at 7 degrees C. Dissociation of cells from normal mesonephros fragments was minimal at both temperatures. It has been shown else-where that this frog tumor elaborates collagenase in a temperature-dependent manner. More collagenase is detected at 30 degrees C than at 7 degrees C. Normal kidney elaborates low levels of collagenase at both temperatures. Because our results suggested the possibility that some dissociation of the tumor cells may have been attributable to tumor-elaborated collagenase, we studied the effect of two collagenase inhibitors on dissociation. Both EDTA at high concentration and cysteine inhibit collagenase and both diminished tumor-cell dissociation.

Cytoplasmic microtubules of normal and tumor cells of the leopard frog. Temperature effects

The cytoplasmic microtubule complex (CMTC) was examined in monolayer cultures of normal tadpole mesonephros, primary renal adenocarcinoma, and an established cell line derived from a pronephric renal adenocarcinoma (PNKT-4B) of the leopard frog, Rana pipiens. Immunocytochemistry revealed typical arrays of microtubules extending from the cytocentrum to the cell periphery in all three cell types when cultured at 28 degrees C; similar results were obtained at 20 degrees C. However, the CMTC was disorganized in both tumor types, in contrast to the retention of a typical CMTC in normal tissue cultured at 7 degrees C. The response of PNKT-4B cells differed from that of normal tadpole mesonephros when treated with the microtubule inhibitor drug nocodazole. At 28 degrees C, PNKT-4B and tadpole mesonephros cells lost their CMTC with nocodazole treatment, and both were able to reconstitute CMTC when nocodazole was removed. Similarly, both lost CMTC organization with nocodazole and culture at 70 degrees C. However, while normal cells could effect a recovery at 7 degrees C after the removal of nocodazole, PONKT-4B cells were unable to restructure CMTC under the same conditions. Metastasis in the frog renal adenocarcinoma is temperature-dependent, with an elevated prevalence of metastasis in tumor-bearing frogs maintained at 28 degrees C. Few metastatic colonies are detected in tumor-bearing frogs maintained at a low temperature (7 degrees C). Other studies have indicated that microtubules, which are essential for cell motility, play an important role in the invasion by tumor cells of normal tissue fragments in vitro. The effects of temperature on metastasis of the Lucke renal adenocarcinoma are consistent with temperature-mediated changes in tumor-cell CMTC.

Changes in nucleolar and ribosomal RNA of the frog kidney after malignant transformation by the Lucke tumor herpesvirus

Malignant transformation of the frog kidney by the Lucke herpesvirus changes the nucleotide base composition of normal kidney nucleolar and ribosomal RNA. In the Lucke tumor there is a moderate decline in guanylic acid and a sharp decline in adenylic acid levels. Conversely, there is a sharp increase in cytidylic acid and uridylic acid levels in the tumor cells. However, there was an increase in the G + C content of nucleolar and ribosomal RNA over that obtained from the normal kidney cells. Nearly identical quantitative changes in the base composition of each RNA species were measured for the adult (spontaneous) mesonephric carcinoma and a Lucke-herpesvirus-induced pronephric tumor cell line; similar correspondence was obtained for the normal adult mesonephros and a normal pronephric cell line.

The etiology of renal-cell carcinoma

Experimental renal-cell carcinoma can be induced by many different chemical carcinogens; dimethyl nitrosoamine has been most studied. The disease so induced in experimental animals closely resembles the spontaneous disease in man in histopathology, course, and other characteristics. Two agents that are probably etiological of renal-cell cancer in man are tobacco and the analgesic, phenacetin; however, these materials can account for only a minority of the cases. The predominance of males in adult renal carcinoma might be explained by the more efficient metabolic activation of carcinogens by renal enzymes that are induced by male hormones. Mouse experiments support this hypothesis. Studies utilizing human kidney tissues that would test the hypothesis in man can and should be done. No obvious clues have emerged to explain the wide geographic differences in incidence of renal carcinoma. No group of industrial workers, or of others with a unique environment, has yet been described that has an especially high incidence of renal-cell carcinoma. A minority of renal carcinomas are familial. They represent a number of different diseases, one of which is associated with the von Hippel-Lindau disease. The hereditary renal-cell carcinoma of the Ecker rat, which is transmitted as an autosomal dominant, provides a useful laboratory model for hereditary carcinoma of man. Recently, two human families with renal-cell carcinoma were described in which there were unique chromosomal abnormalities associated with the disease. Such changes have been linked with oncogene activation in the instance of other tumors. Further studies of chromosomal abnormalities in renal-cell carcinoma will probably define a common pattern of chromosomal rearrangements. While estrogen readily induces renal-cell carcinoma in hamsters other species, including man, appear resistant. An excess of renal-cell carcinoma has not been reported in men on chronic estrogen therapy for prostatic carcinoma, nor has it been associated with the DES syndrome. A virus etiology for renal-cell carcinoma in man comparable to that of the Lucke tumor in frogs is unlikely on epidemiologic, ultrastructural morphologic, and other grounds. There is nothing suggesting horizontal transmission in the human disease, and a unique excess of renal-cell carcinomas in immunosuppressed patients or patients with the acquired immunodeficiency syndrome (AIDS) is not apparent. There is overwhelming evidence that renal adenomas represent early adenocarcinomas, or at least precursor lesions; certainly they are closely related to renal-cell carcinomas.(ABSTRACT TRUNCATED AT 400 WORDS)

Herpesviruses in metastatic Lucké renal adenocarcinoma

The etiologic agent of the renal adenocarcinoma of leopard frogs, Rana pipiens, is the Lucké tumor herpesvirus (LTHV). The virus is easily detected with thin section electron microscopy in primary tumors of frogs which have been exposed to a cold environment. Several spontaneous metastatic nodules and a large primary tumor were detected at autopsy of a frog which had been maintained at 4 degrees C for 73 days. LTHV was found not only in the primary tumor, as previously reported, but also was present in metastatic tumor cells in the liver, fat body, and bladder. The presence of LTHV in metastatic cells demonstrates that the differentiated state of primary Lucké tumor cells is retained in its metastatic colonies even at the fine structure level revealed by electron microscopy.

Effect of thymectomy on development of Lucké renal adenocarcinomas in virus-infected leopard frog tadpoles

Thymectomy of very young leopard frog (Rana pipiens) larvae dramatically reduced in vitro lymphocyte responses to the nitrogen phytohemagglutinin-P and prolonged survival of Lucké tumor alloimplants. However, tumor incidence in premetamorphic or metamorphosing frogs that had received injections as embryos of Lucké tumor herpesvirus (LTHV) was the same in thymectomized and normal immunocompetent animals. This result suggests that T-cell-mediated cytotoxicity does not prevent development of Lucké tumors in immunocompetent larvae and that if tumor-specific transplantation antigens appear, they may induce tolerance rather than destructive immunity in normal LTHV-injected larvae.

Reduced prevalence of the Lucké renal adenocarcinoma in populations of Rana pipiens in Minnesota

Northern leopard frogs (Rana pipiens) afflicted with the Lucké renal adenocarcinoma virtually disappeared from Minnesota in the autumn of 1977. Frogs from four sites in Minnesota counties (Polk, Otter Tail, Kandiyohi, and Scott) with a previously high prevalence of Lucké renal tumor were studied. In the past decade, prevalence averaged 4.2% in 29 collections (total, 1,870 frogs). No tumors were detected in 685 frogs autopsied in the autumn of 1977 by the method of previous studies. Frog collections, each comprised of 20 or more individuals, were compared for the presence or absence of tumor-bearing frogs. Significantly fewer collections contained tumor-bearing frogs in the autumn of 1977 than did collections of previous years.

Frog lysozyme. IV. Isozyme of lysozyme and the Lucké renal adenocarcinoma

The normal kidney of the frog Rana pipiens contains eight isozymes of lysozyme. Three of these, however, were not present in five Lucke renal adenocarcinomas. No isozymes were found to be unique to the tumor kidneys. Of the five isozymes detected in tumor kidneys, only one was uniformly present, a second was present in four of five tumors, and the appearance of the other three was highly variable, although no tumor kidney contained all of them. The uniform absence of the three isozymes and the variable distribution of the other five among the tumors attested to the metabolic uniqueness of this tumor and was consistent with a prior hypothesis concerning the role of lysozyme in the etiology of this herpesvirus-induced tumor.