Reverse transcriptase activity in tissues of the soft shell clam Mya arenaria affected with haemic neoplasia

• Published in: Journal of invertebrate pathology Vol. 102; no. 2; pp. 133 - 140
• Main Authors: AboElkhair, M., Synard, S., Siah, A., Pariseau, J., Davidson, J., Johnson, G., Greenwood, S.J., Casey, J.W., Berthe, F.C.J., Cepica, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.10.2009; Elsevier
• Subjects: Animals; Biological and medical sciences; Digestive System - ultrastructure; Digestive System - virology; DNA, Viral - analysis; DNA, Viral - genetics; Flow Cytometry - veterinary; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Viral; Haemic neoplasia; Hematologic Neoplasms - diagnosis; Hematologic Neoplasms - veterinary; Hematologic Neoplasms - virology; Hemocytes - ultrastructure; Hemocytes - virology; Hemolymph - cytology; Hemolymph - virology; Host-Pathogen Interactions; Invertebrates; Mollusca; Mya - virology; Mya arenaria; Pathology; Retroviridae - enzymology; Retroviridae - pathogenicity; Retroviridae - ultrastructure; Reverse transcriptase; Reverse Transcriptase Polymerase Chain Reaction; RNA-Directed DNA Polymerase - metabolism; TaqMan-PERT; Tissues; Canada; Prince Edward Island Province; North America; America; Mya arenaria; TaqMan-PERT; Haemic neoplasia; Reverse transcriptase; Tissues; Edible mollusc; Animal microorganism relation; RNA-directed DNA polymerase; Disease; Histopathology; Hemocyte; Enzymatic activity; Bivalvia; Pathogenic; Digestive gland; Diagnosis; Enzyme; Transferases; Zoopathogen; Method; Infection; Virus; Nucleotidyltransferases; Invertebrata; Mollusca
• ISSN: 0022-2011; 1096-0805; 1096-0805
• DOI: 10.1016/j.jip.2009.06.009

Since all retroviruses possess reverse transcriptase (RT) enzyme, reverse transcriptase activity has been the main supportive evidence of retroviral etiology of haemic neoplasia (HN) in soft shell clams, Mya arenaria. The objective of the present study was to search for a putative retrovirus in various tissues of diseased clams following quantification of RT activity (biochemical indicator of retroviral infection). The clams were assessed by flow cytometry (FCM) for diagnosis of HN. RT activity was quantified by TaqMan-product enhanced reverse transcriptase (TM-PERT) assay in four different organs, gonad, gills, digestive gland, and mantle, at various stages of HN. The digestive gland, the organ with the highest RT activity, and haemocytes, the target cell of HN, were assessed by EM for presence of retroviruses. All organs were assessed by histology. The results of this study demonstrated that although all organs of healthy clams have some background RT activity, the activity observed in most of organs of diseased clams was significantly increased ( p < 0.05). An association was observed between the degree of neoplastic cell infiltration and the level of RT activity. Digestive gland showed the highest and most consistent RT activity in both healthy and diseased clams. No evidence for the existence of a retrovirus like particle was found by positive staining EM. The presence of RT activity without indications of retroviral particles in digestive gland and haemocytes suggests a probable endogenous source of RT.