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

NUCLEOTIDE SEQUENCE VARIATIONS OF THE MAJOR STRUCTURAL PROTEINS
(VP15, VP19, VP26 AND VP28) OF WHITE SPOT SYNDROME VIRUS (WSSV), A PATHOGEN
OF CULTURED LITOPENAEUS VANNAMEI IN MEXICO
Zinnia J. Molina Garza, Lucio Galaviz Silva and J. Reyes González Galaviz
Universidad Autónoma de Nuevo León]
Facultad de Ciencias Biológicas
molinazinnia@hotmail.com
Since 1992, white spot syndrome virus (WSSV) has caused severe damage to the global shrimp farming industry and is the
most devastating shrimp viral pathogen currently known. White spot syndrome virus (WSSV) was first reported in farmed
Litopenaeus vannamei stocks in Sinaloa and Sonora, Mexico during 1999 and continues to cause severe shrimp losses.
White spot syndrome virus particles were purified from L. vannamei collected during epizootics from shrimp farms located in
Sinaloa, Nayarit and Sonora, Mexico.
Open reading frame fragments that encode the described proteins were amplified from the purified WSSV Mexican isolate (Fig.
1). The amplified PCR products fitted in the expected positions and corresponded to vp28 (516 bp), vp19 (363 bp), vp26 (569
bp) and vp15 (311 bp).
WSSV genes encoding nucleocapsid (VP26 and VP15) and envelope proteins (VP19 and VP28) of a Mexican isolate were
cloned in the pMosBlue vector. The nucleotide sequences of these genes were compared with WSSV isolates in GenBank.
VP15 is highly conserved, and VP26 showed 99% homology to a Chinese isolate. The VP28 fragment demonstrated 100%
homology to the majority of the isolates analysed (UniProt accession no. Q91CB7), differing from two Indian WSSV and one
Chinese WSSV isolates by two non-conserved and one conserved replacements, respectively. Because of their highly conserved
nature, these three structural proteins are good candidates for the development of antibody-based WSSV diagnostic tools
or for the production of recombinant protein vaccines to stimulate the quasi-immune response of shrimp. In contrast, VP19 of
the Mexican isolate was distinguishable from almost all isolates tested, including an American strain of WSSV (US98/South
Carolina, GenBank accession no. AAP14086). Although homology was found with isolates from Taiwan (GenBank accession
no. AAL89341) and India.
Figure 1 Agarose-gel electrophoresis
showing PCR products of four genomic
regions that encode WSSV nucleocapsid
and envelope proteins. Lane M, DNA
marker, lane 1, vp15 (311 bp); lane 2,
vp19 (363 bp); lanes 3 and 4, vp26; lane
5, vp28.
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