Publication: Non-virulence of a recombinant shrimp nidovirus is associated with its non structural gene sequence and not a large structural gene deletion
Issued Date
2009-03-01
Resource Type
ISSN
10960341
00426822
00426822
Other identifier(s)
2-s2.0-60349092153
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Mahidol University
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SCOPUS
Bibliographic Citation
Virology. Vol.385, No.1 (2009), 161-168
Suggested Citation
Warachin Gangnonngiw, Gun Anantasomboon, Wiwat Sang-oum, Siriporn Sriurairatana, Kallaya Sritunyalucksana, Timothy W. Flegel Non-virulence of a recombinant shrimp nidovirus is associated with its non structural gene sequence and not a large structural gene deletion. Virology. Vol.385, No.1 (2009), 161-168. doi:10.1016/j.virol.2008.10.044 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/27734
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Title
Non-virulence of a recombinant shrimp nidovirus is associated with its non structural gene sequence and not a large structural gene deletion
Abstract
RT-PCR using a commercial kit for yellow head virus (YHV) detection in growth-retarded shrimp yielded an unusual 777 bp amplicon instead of expected amplicons of 277 bp for YHV type-1 (YHV-1) or 406 bp for YHV type-2 (YHV-2). Cloning and sequencing (GenBank EU170438) revealed approximately 80% identity to non-structural (NS) ORF1b sequences of both YHV-1 (GenBank AA083987) and YHV-2 (GenBank AF227196), indicating an atypical YHV type (A-YHV) phylogenetically equidistant from both types. An RT-PCR test specifically designed for A-YHV revealed that it was uncommon and that its occurrence in shrimp culture ponds did not correlate with growth retardation or mortality. By immunohistochemistry with YHV-specific monoclonal antibodies, the A-YHV gave positive reactions for envelope protein gp64 and capsid protein p20, but not for envelope protein gp116, even though gp116 and gp64 originate from a polyprotein of ORF3. Lack of gp116 immunoreactivity correlated with a large ORF3 deletion (GenBank EU123854) in the region of the protein targeted by an MAb against gp116. Transmission electron microscopy of A-YHV-infected shrimp revealed only unenveloped pre-virions. During manuscript revision, information received revealed that typing of YHV isolates based on sequences of ORF1b and ORF3 had yielded several geographical types, including one virulent type (YHV-1b) with an ORF3 deletion sequence that matched the sequence of A-YHV. Using these sequences and an additional A-YHV sequence (EU853170) from the ORF1b typing region, A-YHV potentially represents a recombinant between type 1b and type 5. SDS-PAGE and Western blot analysis revealed that type 1b produced a gp116 deletion protein that did not bind with the MAb or polyclonal Ab to normal gp116. Overall, the information suggested that lack of A-YHV virulence was associated with the NS gene sequence linked to ORF1b rather than the deletion in ORF3. © 2008 Elsevier Inc. All rights reserved.