Palmarini M, Holland M J, Cousens C, Dalziel R G, Sharp J M
Moredun Research Institute, Edinburgh, UK.
J Gen Virol. 1996 Dec;77 ( Pt 12):2991-8. doi: 10.1099/0022-1317-77-12-2991.
Jaagsiekte retrovirus (JSRV) is an exogenous type D-related retrovirus specifically associated with a contagious lung cancer of sheep (sheep pulmonary adenomatosis; SPA). Recently, epithelial tumour cells in the lungs of SPA-affected sheep were identified as major sites of JSRV replication by immunological techniques and RT-PCR amplification of part of JSRV gag. JSRV was not detected outside the lungs and their draining lymph nodes. However, low levels of JSRV expression in non-respiratory tissues could have been masked by co-amplification of endogenous JSRV-related sequences, which were differentiated from JSRV by the lack of a Scal restriction site in the PCR product. To further investigate the pathogenesis of SPA, an exogenous virus-specific hemi-nested PCR was developed utilizing primers in the U3 region of JSRV LTR, where major differences between endogenous and exogenous sequences exist. This technique was shown to be > or = 10(5)-fold more sensitive than the previous gag PCR/ScaI digestion method. Using this new assay the tissue distribution of JSRV in sheep with natural and experimentally induced SPA was analysed. Proviral DNA and JSRV transcripts were found in all tumours and lung secretions of SPA-affected sheep (n = 22) and in several lymphoid tissues. The mediastinal lymph nodes draining the lungs were consistently demonstrated to be infected by JSRV (10/10). JSRV transcripts were also detected in spleen (7/9), thymus (2/4), bone marrow (4/8) and peripheral blood mononuclear cells (3/7). Proviral DNA was also detected in these tissues although in a much lower proportion of cases. JSRV was not detected in 27 samples from unaffected control animals (n = 15).
绵羊肺腺瘤逆转录病毒（JSRV）是一种外源性D型逆转录病毒，与绵羊的一种传染性肺癌（绵羊肺腺瘤病；SPA）密切相关。最近，通过免疫技术和对JSRV gag部分片段的逆转录聚合酶链反应（RT-PCR）扩增，确定受SPA影响的绵羊肺部的上皮肿瘤细胞是JSRV复制的主要部位。在肺及其引流淋巴结之外未检测到JSRV。然而，非呼吸组织中低水平的JSRV表达可能被内源性JSRV相关序列的共扩增所掩盖，这些内源性序列在PCR产物中因缺乏Scal限制性位点而与JSRV区分开来。为了进一步研究SPA的发病机制，利用JSRV长末端重复序列（LTR）U3区域的引物开发了一种外源性病毒特异性半巢式PCR，该区域存在内源性和外源性序列的主要差异。结果表明，该技术比之前的gag PCR/ScaI消化法敏感10^5倍以上。使用这种新方法分析了自然感染和实验诱导SPA的绵羊中JSRV的组织分布。在受SPA影响的绵羊（n = 22）的所有肿瘤和肺分泌物以及几个淋巴组织中发现了前病毒DNA和JSRV转录本。始终证明引流肺部的纵隔淋巴结被JSRV感染（10/10）。在脾脏（7/9）、胸腺（2/4）、骨髓（4/8）和外周血单核细胞（3/7）中也检测到JSRV转录本。在这些组织中也检测到了前病毒DNA，尽管比例要低得多。在未受影响的对照动物的27个样本（n = 15）中未检测到JSRV。
