Davidson I, Borenstein R
Division of Avian Diseases, Kimron Veterinary Institute, Bet Dagan, Israel.
Acta Virol. 1999 Apr-Jun;43(2-3):136-42.
The avian herpesvirus, Marek's disease virus (MDV) and several retroviruses, reticuloendotheliosis virus (REV), avian leukosis virus (ALV) (chickens) and lymphoproliferative disease virus (turkeys) are oncogenic and immunosuppressive agents. These viruses were detected either alone, or in various combinations in blood and tumor DNAs of commercial birds using PCR. We present a 5-year retrospective study that included 207 chicken and 52 turkey flocks. Of these, 32 chicken and 18 turkey flocks were negative. Of the positive chicken and turkey flocks 76% and 75%, respectively, had a single, while the rest, 24% and 25%, had a multiple virus infection. In the chickens of the multiple virus-infected flocks, 14% and 17% of the blood and tumor DNAs carry dual MDV and REV and/or ALV sequences, that is about 30% of the PCR-positive, and about 5% of the total DNAs analysed. Multiple virus sequences were detected only in the turkey blood DNAs-11% of 84 samples. Following that quantitation we aimed to analyse the molecular status of the retrovirus sequences in order to determine whether retrovirus sequences were integrated into the herpesvirus genome. We focused on the MDV BamH1-H 132 bp tandem repeat fragment proximity using a combined PCR (cPCR) to identify chimeric PCR products. That included amplification with heterologous combinations of the MDV and retroviral LTR primers. In 13 of 35 DNAs that had both MDV and retrovirus sequences new products were produced. Of 4 MDV + REV chimeric products that were sequenced, one was homologous to the Chicken Repeat element 1 non-LTR type retrotransposon. No evidence for a retrovirus LTR integration was found in the 132 bp repeat proximity, but in two of these products we detected nucleotide stretches of 20 bp and 21 bp with a 70% and 71% homology to the REV-LTR. Also, the amplification of the chimeric products using a retrovirus primer denoted that at least short nucleotide stretches homologous to retroviral LTR primer were present in these DNAs, and that they might resemble ancient retroviral insertions, as previously demonstrated (Isfort et al., 1992).
禽疱疹病毒、马立克氏病病毒（MDV）以及几种逆转录病毒，即网状内皮组织增生症病毒（REV）、禽白血病病毒（ALV）（鸡）和淋巴细胞增生性疾病病毒（火鸡），都是致癌和免疫抑制因子。使用聚合酶链反应（PCR）在商业禽类的血液和肿瘤DNA中单独或多种组合地检测到了这些病毒。我们进行了一项为期5年的回顾性研究，涵盖了207个鸡群和52个火鸡群。其中，32个鸡群和18个火鸡群检测为阴性。在检测为阳性的鸡群和火鸡群中，分别有76%和75%感染了单一病毒，其余24%和25%则感染了多种病毒。在感染多种病毒的鸡群中，14%的血液DNA和17%的肿瘤DNA携带MDV与REV和/或ALV的双重序列，即约占PCR阳性结果的30%，以及所分析总DNA的约5%。仅在火鸡血液DNA中检测到多种病毒序列——84个样本中的11%。在进行定量分析之后，我们旨在分析逆转录病毒序列的分子状态，以确定逆转录病毒序列是否整合到疱疹病毒基因组中。我们使用联合PCR（cPCR）聚焦于MDV BamH1 - H 132 bp串联重复片段附近区域，以鉴定嵌合PCR产物。这包括使用MDV和逆转录病毒长末端重复序列（LTR）引物的异源组合进行扩增。在35个同时含有MDV和逆转录病毒序列的DNA样本中，有13个产生了新产物。在对4个MDV + REV嵌合产物进行测序后，发现其中一个与鸡重复元件1非LTR型逆转座子同源。在132 bp重复片段附近未发现逆转录病毒LTR整合的证据，但在其中两个产物中，我们检测到了长度为20 bp和21 bp的核苷酸片段，与REV - LTR的同源性分别为70%和71%。此外，使用逆转录病毒引物对嵌合产物进行扩增表明，这些DNA中至少存在与逆转录病毒LTR引物同源的短核苷酸片段，并且它们可能类似于先前已证明的古老逆转录病毒插入序列（伊斯福特等人，1992年）。
