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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03707

    Virulence and genetic differences among white spot syndrome virus isolates inoculated in Penaeus vannamei

    Álvaro Hernández-Montiel, Ivone Giffard-Mena*, Manfred Weidmann, Michael Bekaert, Kristina Ulrich, Jessica Benkaroun

    *Corresponding author:

    ABSTRACT: White spot syndrome virus (WSSV) infects several economically important aquaculture species, causing significant losses to the industry. This virus belongs to the Nimaviridae family, and has a dsDNA genome ranging between 257 and 309 kb (more than 20 isolate genomes fully sequenced and published to date). Multiple routes of infection could be the cause of the high virulence and mortality rates detected in shrimp species. Particularly in Penaeus vannamei, differences in isolate virulence have been observed, along with controversy over whether deletions or insertions are associated with virulence gain or loss. The pathogenicity of three isolates from three localities in Mexico (two from Sinaloa: 'CIAD', and 'Angostura', and one from Sonora: 'Sonora') was evaluated in vivo in whiteleg shrimp (P. vannamei) infection assays. Differences were observed in shrimp mortality rate among the three isolates, of which Sonora was the most virulent. Subsequently, the complete WSSV – Sonora and Angostura genomes were sequenced in depth from infected shrimp tissues and assembled in reference to the genome of isolate strain CN01 (KT995472), which comprised 289,350 bp and 288,995 bp, respectively. Three deletion zones were identified compared to CN01 comprising 15 genes, including three envelope proteins VP41A, VP52A, and VP41B, one non-structural protein ICP35 and 11 others encoding proteins whose function is currently unknown. In addition, five genes (wsv129, wsv178, wsv204, wsv249, and wsv497) show a modified number of repeat motifs. The main implications and possible effects on viral infection of these modifications are discussed.