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Dicistroviruses of Crustaceans
Chapter 33
Dicistroviruses of Crustaceans F.S.B. Kibenge University of Prince Edward Island, Charlottetown, PE, Canada
33.1 SOME NOTES ON THIS CHAPTER The family Dicistroviridae contains viruses of insects and crustaceans and is divided into two genera: Cripavirus and Aparavirus. The acronym Dicistro is derived from the two open reading frames (ORFs), or cistrons, encoded in the positive-sense, singlestranded RNA (ssRNA) genome whereby each ORF is translated from an independent internal ribosome entry site (IRES). The family belongs to the order Picornavirales (Le Gall et al., 2008; Chen et al., 2012) but differs from Picornaviridae in having the structural proteins at the 3' end of the genome rather than at the 5' end, and by the presence of the intergenic region (IGR) (Bonning, 2009), which serves as the IRES for ORF2. Taura syndrome virus (TSV), which infects many species of shrimp, prawn and crab (Anonymous, 2013), is in the genus Aparavirus, although the phylogenic tree for the 5′ non-structural polyprotein (ORF1) places it in Cripavirus instead of Aparavirus and thus may belong to a novel genus of family Dicistroviridae (Hertz and Thompson, 2011). Taura syndrome virus is second only to white spot syndrome disease virus (WSSDV) in terms of economic importance to the global shrimp farming industry. Recently, a new virus, Scylla bicistronic virus–1 (mud crab dicistrovirus-l, MCDV-l) was isolated from diseased farmed Portunidae hole crab (Anonymous, 2015). During the writing of this book, it became clear to the editors that it would not be possible to find contributors to this chapter in a timely manner because the international experts who used to work on these viruses are all retired, and there are not many “pure shrimp virologists” available, as there are no cell lines to grow shrimp viruses. So, most of the work on shrimp viral diseases is a combination of pathology and virology, and the “shrimp pathologists” believe that they are not qualified to write shrimp virology chapters. In order to help foster understanding of the historic importance and capacity of TSV to cause disease and the methods used for its detection, readers are referred to the review article by Don V. Lightner, R. M. Redman, Carlos R. Pantoja, Kathy F. J. Tang, Brenda L. Noble, Paul Schofield, L. L. Mohney, Linda M. Nunan and S. A. Navarro, “Historic emergence, impact and current status of shrimp pathogens in the Americas,” from Journal of Invertebrate Pathology (2012), which describes the status of shrimp viruses in the Americas.
REFERENCES Anonymous, 2013. Taura Syndrome – Fact Sheet. Available at:. Anonymous, 2015. Patent Application, Nucleic Acid Probe for Detecting Blue Crab Dicistroviridae-1, Kit and Using Method Thereof CN 104561388 A. Available at: . Bonning, B.C., 2009. The Dicistroviridae: an emerging family of invertebrate viruses. Virologica Sinica 24, 415–427. Chen, Y.P., Nakashima, N., Christian, P.D., Bakonyi, T., Bonning, B.C., Valles, S.M., et al., 2012. In: King, A.M.Q., Adams, M.J., Carstens, E.B., Lefkowitz, E.J. (Eds.), Virus Taxonomy, 9th Report of the International Committee on Taxonomy of Viruses, pp. 840–845 (1327 p.). Hertz, M.I., Thompson, S.R., 2011. Mechanism of translation initiation by Dicistroviridae IGR IRESs. Virology 411, 355–361. Le Gall, O., Christian, P., Fauquet, C.M., King, A.M., Knowles, N.J., et al., 2008. Picornavirales, a proposed order of positive-sense ssRNA viruses with a pseudo-T= 3 virion architecture. Arch. Virol. 153, 715–727. Lightner, D.V., Redman, R.M., Pantoja, C.R., Tang, K.F.J., Noble, B.L., Schofield, P., et al., 2012. Historic emergence, impact and current status of shrimp pathogens in the Americas. J. Invertebr. Pathol. 110, 174–183.
Aquaculture Virology. DOI: http://dx.doi.org/10.1016/B978-0-12-801573-5.00033-4 © 2016 Elsevier Inc. All rights reserved.
473
Dicistroviruses of Crustaceans F.S.B. Kibenge University of Prince Edward Island, Charlottetown, PE, Canada
33.1 SOME NOTES ON THIS CHAPTER The family Dicistroviridae contains viruses of insects and crustaceans and is divided into two genera: Cripavirus and Aparavirus. The acronym Dicistro is derived from the two open reading frames (ORFs), or cistrons, encoded in the positive-sense, singlestranded RNA (ssRNA) genome whereby each ORF is translated from an independent internal ribosome entry site (IRES). The family belongs to the order Picornavirales (Le Gall et al., 2008; Chen et al., 2012) but differs from Picornaviridae in having the structural proteins at the 3' end of the genome rather than at the 5' end, and by the presence of the intergenic region (IGR) (Bonning, 2009), which serves as the IRES for ORF2. Taura syndrome virus (TSV), which infects many species of shrimp, prawn and crab (Anonymous, 2013), is in the genus Aparavirus, although the phylogenic tree for the 5′ non-structural polyprotein (ORF1) places it in Cripavirus instead of Aparavirus and thus may belong to a novel genus of family Dicistroviridae (Hertz and Thompson, 2011). Taura syndrome virus is second only to white spot syndrome disease virus (WSSDV) in terms of economic importance to the global shrimp farming industry. Recently, a new virus, Scylla bicistronic virus–1 (mud crab dicistrovirus-l, MCDV-l) was isolated from diseased farmed Portunidae hole crab (Anonymous, 2015). During the writing of this book, it became clear to the editors that it would not be possible to find contributors to this chapter in a timely manner because the international experts who used to work on these viruses are all retired, and there are not many “pure shrimp virologists” available, as there are no cell lines to grow shrimp viruses. So, most of the work on shrimp viral diseases is a combination of pathology and virology, and the “shrimp pathologists” believe that they are not qualified to write shrimp virology chapters. In order to help foster understanding of the historic importance and capacity of TSV to cause disease and the methods used for its detection, readers are referred to the review article by Don V. Lightner, R. M. Redman, Carlos R. Pantoja, Kathy F. J. Tang, Brenda L. Noble, Paul Schofield, L. L. Mohney, Linda M. Nunan and S. A. Navarro, “Historic emergence, impact and current status of shrimp pathogens in the Americas,” from Journal of Invertebrate Pathology (2012), which describes the status of shrimp viruses in the Americas.
REFERENCES Anonymous, 2013. Taura Syndrome – Fact Sheet. Available at:
Aquaculture Virology. DOI: http://dx.doi.org/10.1016/B978-0-12-801573-5.00033-4 © 2016 Elsevier Inc. All rights reserved.
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