Department of Pathology and Microbiology, Atlantic Veterinary College, Charlottetown, PE, Canada C1A 4P3.
J Invertebr Pathol. 2012 Jan;109(1):97-104. doi: 10.1016/j.jip.2011.10.008. Epub 2011 Oct 21.
Haemic neoplasia (HN) is a leukemia-like disease that affects at least 20 species of marine bivalves including soft shell clam, Mya arenaria. Since the disease was discovered in 1969, the etiology remains unknown. A retroviral etiology has been suggested based on the detection of reverse transcriptase activity and electron microscopic observation of retroviral-like particles using negative staining. To date, however no virus isolate and no retroviral sequence from HN has been obtained. Moreover, transmission of the disease by cell-free filtrate from affected clams has not been reproduced. In the current study, we reinvestigated the association of HN with a putative retrovirus. Sucrose gradient centrifugation followed by assessment of reverse transcriptase activity, electrophoretic analysis of protein and RNA, and electron microscopic examinations of fractions corresponding to retroviral density were employed. Detection of retroviral pol sequences using degenerate RT-PCR approaches was also attempted. Our results showed visible bands at the expected density of retrovirus in HN-positive and HN-negative clam tissues and both with reverse transcriptase activity. Electron microscopy, RNA analysis, protein analysis, and PCR systems targeting the pol gene of retroviruses did not however provide clear evidence supporting presence of a retrovirus. We point out that the retrovirus etiology of HN of Mya arenaria proposed some 25 years ago should be reconsidered in the absence of a virus isolate or virus sequences.
血癌（HN）是一种类似白血病的疾病，影响至少 20 种海洋双壳贝类，包括软壳蛤，Mya arenaria。自 1969 年发现该病以来，病因仍不清楚。基于逆转录酶活性的检测和使用负染色的逆转录病毒样颗粒的电子显微镜观察，提出了逆转录病毒病因。然而，迄今为止，尚未从 HN 获得病毒分离物和逆转录病毒序列。此外，未通过受影响蛤的无细胞滤液传播该疾病。在本研究中，我们重新研究了 HN 与假定的逆转录病毒之间的关联。采用蔗糖梯度离心，然后评估逆转录酶活性、蛋白质和 RNA 的电泳分析以及对应于逆转录病毒密度的馏分的电子显微镜检查。还尝试使用简并 RT-PCR 方法检测逆转录病毒 pol 序列。我们的结果显示，在 HN 阳性和 HN 阴性蛤组织中均在预期的逆转录病毒密度处可见带，并且均具有逆转录酶活性。然而，电子显微镜、RNA 分析、蛋白质分析和针对逆转录病毒 pol 基因的 PCR 系统并未提供明确证据支持存在逆转录病毒。我们指出，由于缺乏病毒分离物或病毒序列，大约 25 年前提出的 Mya arenaria 的 HN 逆转录病毒病因应该重新考虑。
