Detection of white spot syndrome virus in filtered shrimp-farm water fractions and experimental evaluation of its infectivity in Penaeus ( Litopenaeus) vannamei

• Published in: Aquaculture 2009-07, Vol.292 (1), p.16-22
• Main Authors: Esparza-Leal, Héctor M., Escobedo-Bonilla, César M., Casillas-Hernández, Ramón, Álvarez-Ruíz, Píndaro, Portillo-Clark, Guillermo, Valerio-García, Roberto C., Hernández-López, Jorge, Méndez-Lozano, Jesús, Vibanco-Pérez, Norberto, Magallón-Barajas, Francisco J.
• Format: Article
• Language: English
• Subjects: Aquaculture; Differential filtration; differential filtrration; disease detection; disease outbreaks; dsDNA viruses; farmed animal species; hemolymph; Infectivity assay; Litopenaeus vannamei; Marine; microalgae; Penaeus; Penaeus ( Litopenaeus) vannamei; Plankton; Pond water; Shellfish; shrimp; shrimp culture; Shrimp farm; Viruses; water quality; white spot syndrome; White spot syndrome virus; WSSV; zooplankton
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2009.03.021

White spot syndrome virus (WSSV) may spread through water to neighbor ponds or farms. Routine water exchange and wastewater released during white spot disease (WSD)-emergency harvests may preserve WSSV in shrimp farming areas. To test this hypothesis, on-site experiments were performed in a WSSV-affected farm in Guasave, Sinaloa, Mexico. Plankton and shrimp hemolymph were collected from 12 ponds during a WSD outbreak. PCR analyses showed that 72% of the hemolymph pools (26 out of 36) were WSSV-positive. In contrast, only 14% (4 of 28) plankton samples (filtered through 10 and 0.45 µm) from three ponds (2, 7 and 10) were WSSV-positive. Plankton from pond 9 was WSSV-negative, but 14 days later, shrimp began to die. At this point, a differential filtration experiment was performed in pond 9. WSSV-positive samples were only found in three fractions [particulate fraction (PF) 1 µm and liquid fractions (LF) < 100 and < 40 µm]. Both LFs and PFs were used for in situ infectivity assays by water-borne routes in WSSV-negative whiteleg shrimp Penaeus ( Litopenaeus) vannamei. Some shrimp exposed to different PFs and LFs (100 µm to > 0.65 µm) became WSSV-positive. Results indicate that water fractions between 100 and 0.65 µm induced WSSV infection to shrimp. Results showed that pond water and/or particulate fractions are vehicles for WSSV dispersion via virus suspended in water, attached to microalgae, or carried by zooplankton.