Molecular characterization of a unique retrovirus associated with a fish tumor

Abstract

The walleye dermal sarcoma is a mesenchymal tumor which seasonally affects up to 27 % of adult walleye fish (Stizostedion vitreum). It arises multicentrically in the dermis, in which its development remains restricted. We report the molecular cloning of a type C retrovirus from this tumor. The genome of this virus (13.2 kb) is larger than that of all retroviruses and in that respect is approximated only by the recently characterized spumaviruses. In tumors, the predominantly unintegrated linear viral DNA has a single-stranded gap region which is similar to the structure found in some lentiviruses and all spumaviruses. The presence of at least four viral transcripts suggests that this virus has the capacity to encode accessory functions and is reminiscent of the transcriptional complexity of lentiviruses and spumaviruses.

Communications: Comparison of Fall and Spring Tumors as Inocula for Experimental Transmission of Walleye Dermal Sarcoma

“…Cell-free filtrates of spring and fall tumors were analy/ed for the presence of WDSV RNA. Consistent with previous studies, a full-length (12-kilobase) viral genomic transcript was readily visualized in the spring tumor sample by northern blot analysis (Martineau et al 1992), but it was not demonstrable in the fall tumor inoculum (Figure I) from walleye discrete epidermal hyperplasia or to normal walleye skin RNA was observed, supporting the exogenous nature of WDSV.…”

“…Analysis of total RNA from independent fall tumors showed that only low levels of a subgenomic WDSV transcript were found. The presence of this viral message, which likely encodes an accessory gene (Martineau et al 1992), could be an integral component of the mechanism for WDS induction.…”

“…The causative virus, termed walleye dermal sarcoma virus (WDSV), was cloned from tumor tissue and characteri/ed as a member of the family Retroviridae (Martineau et al 1991(Martineau et al , 1992. Walleye dermal sarcoma virus has been observed by electron microscopy in spring-collected tumors (Walker 1969, Yamamoto et al 1985.…”

Walleye dermal sarcoma virus Orf B functions through receptor for activated C kinase (RACK1) and protein kinase C

“…Dermal sarcoma in walleye (Sander vitreus) is etiologically associated with the complex retrovirus, walleye dermal sarcoma virus (WDSV) (Martineau et al, 1992;Martineau et al, 1991;Walker, 1969;Yamamoto, Kelly, and Nielsen, 1985;Yamamoto et al, 1976). Walleye dermal sarcoma (WDS) is exceptional in its seasonal nature.…”

Seasonal Occurrence of Virally Induced Skin Tumors in Wild Fish

“…Retrovirus particles have been observed by Walker (1961) and later by Yamamoto et al (1985b) in walleye tumors. Walleye dermal sarcoma virus (WDSV) genome has been cloned directly from tumors and sequenced, showing that it is a complex retrovirus (Martineau et al 1991(Martineau et al , 1992Holzschu et al 1995). Virions of WDSV have been observed by electron microscopy, and the genome has been detected by in situ hybridization in tumors at high levels when collected in the spring (Poulet et al 1995).…”