Estimation of genetic parameters for survival to multiple isolates of Taura syndrome virus in a selected population of Pacific white shrimp Penaeus (Litopenaeus) vannamei

Taura syndrome virus (TSV) is an economically important pathogen of the Pacific white shrimp, Penaeus (Litopenaeus) vannamei. To date, >40 unique TSV isolates have been identified and phylogenetic analyses of these isolates have revealed four distinct genetic groups named according to their geographic origin: Americas, Belize, South East Asia, and Venezuela. Although there is evidence that virulence varies among different TSV isolates, little is known about how shrimp survival is correlated among isolates (i.e. genetic correlations). In addition, estimates of genetic correlation between TSV survival and other commercially important traits are limited. The objectives of this study were to (1) estimate genetic correlations for shrimp survival to a genetically diverse suite of TSV isolates and (2) estimate genetic correlations between isolate-specific TSV survival and growout performance traits (i.e. growth and growout survival). A total of 180 full-sib families were challenged with TSV: 130 families challenged with Americas and Belize group isolates and 50 families challenged with isolates from all four genetic groups. In addition, 100 of these families were tested for growout performance in a recirculating aquaculture system (RAS) at intensive stocking densities (>230 shrimp/m(2)). All families were from a shrimp line selected for TSV resistance and growth over multiple generations. Genetic correlations for survival among TSV isolates were positive and of moderate to high magnitude (r(G) = 0.35-0.99). Genetic correlations for TSV survival and RAS growth were all negative, but of low magnitude (r(G) = -0.07 to -0.29). Correlations between TSV survival and RAS survival varied from slightly negative to moderately positive. These results indicate that breeding for survival to any one of the four TSV isolates evaluated in this study should, in general, improve survival to the other isolates. Results also suggest that there are no significant costs associated with selection for TSV resistance relative to growout performance. (C) 2013 Elsevier B. V. All rights reserved.