February 15-18, 2009 Washington State Convention Center Seattle ...

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CHARACTERIZATION OF THE TAURA SYNDROME VIRUS ISOLATE ORIGINATING
FROM THE 2004 TEXAS EPIZOOTIC IN CULTURED SHRIMP
Arun K. Dhar, Dilip K. Lakshman, Keenan Amundsen, Refugio Robles-Sikisaka, Krista N. Kaizer, Sribash Roy,
Kenneth W. Hasson and F. C. Thomas Allnutt
Advanced BioNutrition Corporation
7155-H Columbia Gateway Drive
Columbia, Maryland 21046 USA
ADhar@abn-corp.com
Taura syndrome virus (TSV) is a major viral pathogen of penaeid shrimp worldwide. A comprehensive investigation of the
Texas isolate of TSV that caused epizootics in shrimp farms in Texas in 2004 (Us04Pv1) revealed that the virus was highly virulent
in laboratory bioassays causing severe symptom development and rapid mortality. Histopathology of moribund animals
demonstrated epithelial necrosis within the stomach, appendages, general body cuticle and gills. Animals that survived lethal
infection demonstrated moderate to numerous lymphoid organ spheroids (LOS), suggestive of chronic phase TSV infection.
In situ hybridization with a TSV-specific probe detected the virus in the LOS. Transmission electron microscopy of the virus
purified from infected shrimp showed that the virions are 31 nm in diameter with icosahedral symmetry. The genome of the
Us04Pv1 isolate was cloned, sequenced in its entirety and compared to five other geographically distinct TSV isolates for which
complete genome sequences are available in the GenBank database. Comparative genome analysis at the nucleotide and amino
acid levels showed that the Us04Pv1 isolate is more closely related to TSV isolates from Thailand and China and only distantly
related to the Venezuelan TSV isolate. Computational prediction indicated that the tertiary structures of the IAP and protease
domains of all six TSV isolates were very similar. However, the data from our 3-D modeling showed that the RdRp of Us94Pv1
has significant structural differences from the respective domains of five other TSV isolates. It remains to be determined if the
structural differences of TSV RdRps play a significant role in virulence or ecological adaptability of this isolate.