The exogenous form of Jaagsiekte retrovirus is specifically associated with a contagious lung cancer of sheep

Abstract

Sheep pulmonary adenomatosis ([SPA] ovine pulmonary carcinoma) is a transmissible lung cancer of sheep that has been associated etiologically with a type D-and B-related retrovirus (jaagsiekte retrovirus [JSRV]). To date it has been impossible to cultivate JSRV in vitro and therefore to demonstrate the etiology of SPA by a classical approach. In addition, the presence of 15 to 20 copies of endogenous JSRV-related sequences (enJSRV) has hampered studies at the molecular level. The aim of this study was to investigate whether the expression of exogenous JSRV was specifically associated with neoplasia in SPA-affected animals. Initially, we found that enJSRVs were transcribed in a wide variety of normal sheep tissues. Then, by sequencing part of the gag gene of enJSRV we established a ScaI restriction site in gag as a molecular marker for the exogenous form of JSRV. Restriction enzyme digestion of PCR products obtained from the amplification of cDNA from a total of 65 tissues collected from SPA-affected and unaffected control sheep revealed that the exogenous form of JSRV was exclusively and consistently present in tumor tissues and lung secretions of the affected animals. In addition, exogenous JSRV provirus was detected only in DNA from SPA tumors and not from nontumor tissues of the same animals. This study has demonstrated clearly that the exogenous form of JSRV is specifically associated with SPA tumors.

PCR-based detection and partial characterization of a retrovirus associated with contagious intranasal tumors of sheep and goats

“…Total RNA was extracted from pooled sucrose gradient fractions, from 100 l of concentrated nasal fluid, from 100 l of SPA lung fluid, or from 0.2 to 0.5 g of tissue by the acid guanidinium thiocyanatephenol-chloroform method (2). cDNA was synthesized by random-primed RT as described previously (15).…”

“…gag PCR. The primers and conditions used for PCR of cDNA or of genomic DNA were exactly as described previously (15): P1 (sense), 5Ј-GCTGCTTTRA GACCTTATCGAAA-3Ј; and P2 (antisense), 5Ј-ATACTGCAGCYCGATGGC CAG-3Ј). PCR products were detected by electrophoresis through a 2% agarose gel in 1ϫ Tris-borate-EDTA buffer in the presence of 0.5 g of ethidium bromide per ml.…”

“…In the case of SPA, an association with a type B/D retrovirus, known as jaagsiekte sheep retrovirus (JSRV), is well established (15,17), and the complete nucleotide sequence of the retrovirus has been determined (22). Recent reports have demonstrated that JSRV is related to sheep endogenous retroviruses (SERVs), of which there are 10 to 15 copies in the sheep genome (1,12,15). However, reverse transcription-PCR (RT-PCR)-based techniques, which differentiate JSRV from SERVs, showed that JSRV is a distinct exogenous virus that is associated exclusively with SPA tumors (15).…”

“…Recent reports have demonstrated that JSRV is related to sheep endogenous retroviruses (SERVs), of which there are 10 to 15 copies in the sheep genome (1,12,15). However, reverse transcription-PCR (RT-PCR)-based techniques, which differentiate JSRV from SERVs, showed that JSRV is a distinct exogenous virus that is associated exclusively with SPA tumors (15).…”

Retrovirus Vectors Bearing Jaagsiekte Sheep Retrovirus Env Transduce Human Cells by Using a New Receptor Localized to Chromosome 3p21.3

“…JSRV has been classified as a type D retrovirus, based on genomic organization, but has a type B-like Env protein (61). The sheep genome carries multiple copies of JSRV-like endogenous sheep retrovirus (ESRV) sequences (25,27,61), but subsequent studies have shown that JSRV is an exogenous virus distinct from ESRV sequences (4,5,44) and is specifically associated with OPC. Recent studies by Palmarini et al (48) using an infectious molecular clone of JSRV have confirmed that JSRV is the causative agent of OPC.…”