DAO 84:57-63 (2009)  -  DOI: https://doi.org/10.3354/dao02038

Reverse transcriptase activity associated with haemic neoplasia in the soft-shell clam Mya arenaria

M. AboElkhair1, A. Siah1, K. F. Clark2, P. McKenna1, J. Pariseau1,3, S. J. Greenwood1,2, F. C. J. Berthe4, A. Cepica1,*

1Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada
2AVC Lobster Science Centre, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada
3Institut des Sciences de la mer, Université du Québec à Rimouski, Rimouski, Québec G5L 3A1, Canada
4European Food Safety Authority (EFSA), Animal Health and Welfare Panel, 43100 Parma, PR, Italy
*Corresponding author. Email:

ABSTRACT: Reverse transcriptase (RT) activity has been reported in bivalves affected by haemic neoplasia (HN). Since all retroviruses have RT, detection of RT activity was regarded as evidence for the retroviral etiology of HN. This study investigates the relationship between RT levels and the progress of HN as indicated by percentages of tetraploid cells in soft-shell clams Mya arenaria. The percentages of tetraploid cells were estimated by flow cytometry, and the RT levels were quantified using TaqMan product-enhanced RT (TM-PERT) assay. Results demonstrated that the amount of RT was positively correlated with the percentage of tetraploid cells circulating in clam haemolymph (R2 = 0.974, p < 0.001). Compared to HN-negative clams (<5% tetraploid cells), 2 stages with significantly elevated levels of RT activity were observed: the first stage at ~10 to ~20% tetraploid cells, and the second at ~30 to ~80% tetraploid cells (p < 0.01). These data support the well established fact from mammalian models that transformed cells express high levels of non-telomeric RT. The observed increase in RT levels at ~30% tetraploidy coincides with previously reported p53 gene expression. Taken together, this could indicate that using RT levels as an indicator of HN, ≥30% tetraploidy is the stage at which the disease process undergoes a change, and perhaps becomes irreversible.


KEY WORDS: Mya arenaria · Haemic neoplasia · Reverse transcriptase · Polyploidy · TaqMan · Product-enhanced reverse transcriptase assay · PERT


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Cite this article as: AboElkhair M, Siah A, Clark KF, McKenna P and others (2009) Reverse transcriptase activity associated with haemic neoplasia in the soft-shell clam Mya arenaria. Dis Aquat Org 84:57-63. https://doi.org/10.3354/dao02038

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