Controlled bioassay systems for determination of lethal infective doses of tissue homogenates containing Taura syndrome or white spot syndrome virus

Diseases of Aquatic Organisms

Sarah Prior¹  Rolland Laramore¹  Craig L. Browdy¹  Pamela G. Parnell¹  Eleanor F. Shepard¹ 

关键词: TSV;    WSSV;    Bioassay;    Shrimp;    Litopenaeus vannamei;   

DOI  :  10.3354/dao054089

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: In vivo bioassay is the predominant method for evaluating the infectivity of materials potentially harboring viable shrimp pathogens and determining the relative susceptibility of shrimp species to viral infections. A controlled bioassaysystem for white spot syndrome virus (WSSV) and Taura syndrome virus (TSV) was developed utilizing 260 ml tissue culture flasks modified with an air exchange vent. Individual shrimp (1.00 ± 0.25 g) were placed in separate flasks containing artificialseawater (100 to 150 ml) and held in an incubator at 27°C. After a 48 h acclimation period, shrimp were either injected intramuscularly with viral inoculum or exposed to virus-laden water. Water was exchanged and shrimp were fed a commercial food pelletdaily except 24 h post-infection (p.i.). Bioassays were performed with serial dilutions of stock viral preparations and shrimp mortality was recorded for 7 d p.i. Mortality rates of test animals permitted the estimation of the lethal infective doses,LD₅₀ and LD₉₀. The LD₅₀ of the TSV injection preparation was estimated at viral dilutions of 1:7.692 x 10⁷ (Trial 1) and 1:6.667 x 10⁷ (Trial 2). The LD₅₀s of 2 different WSSV injectionpreparations were estimated at 1:4.444 x 10⁶ and 1:4.505 x 10⁶. The LD₅₀ for the TSV waterborne challenge was 1:9916 (Trial 1) and 1:15710 (Trial 2) at 20°C and 1:1272 at 27°C. A second waterborne TSV inoculum challenge at27°C produced an LD₅₀ of 1:2857. WSSV doses used in the waterborne challenge only reached 39% mortality, which did not allow for the estimation of effective lethal doses. Bioassay by injection proved to be a more reliable method of estimatingviral infectivity compared to waterborne method. The dose-response curves developed can serve as a basis for controlled comparisons of relative levels of viral infectivity of specific tissue preparations and for controlled comparisons of relativesusceptibility of shrimp species or stocks to viral pathogens.

【 授权许可】

Unknown