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Virulence and genotypes of white spot syndrome virus infecting Pacific white shrimp Litopenaeus vannamei in north‐western Mexico
Author(s) -
RamosParedes J,
GrijalvaChon J M,
IbarraGámez J C
Publication year - 2017
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.12598
Subject(s) - virulence , biology , white spot syndrome , shrimp , litopenaeus , virology , genotype , virus , microbiology and biotechnology , strain (injury) , gene , genetics , fishery , anatomy
White spot syndrome virus ( WSSV ) has caused substantial global economic impact on aquaculture, and it has been determined that strains can vary in virulence. In this study, the effect of viral load was evaluated by infecting Litopenaeus vannamei with 10‐fold serial dilution of tissue infected with strain WSSV Mx‐H, and the virulence of four WSSV strains from north‐western Mexico was assessed along with their variable number of tandem repeat ( VNTR ) genotypes in ORF 75, ORF 94 and ORF 125. The LD 50 of the Mx‐H strain was a dilution dose of 10 −7.5 ; the mortality titre was 10 9.2 LD 50 per gram. In shrimp injected with 10 2.5 to 10 6.5 LD 50 , no significant virulence differences were evident. Using mortality data, the four WSSV strains grouped into three virulence levels. The Mx‐F strain (intermediate virulence) and the Mx‐C strain (high virulence) showed more genetic differences than those observed between the Mx‐G (low‐virulence) and Mx‐H (high‐virulence) strains, in ORF 94 and ORF 125. The application of high‐viral‐load inocula proved useful in determining the different virulence phenotypes of the WSSV strains from the Eastern Pacific.