White spot syndrome virus infection in cultured Penaeus vannamei (Boone) in Ecuador with emphasis on histopathology and ultrastructure

Mortalities of cultured shrimp, Penaeus vannamei (Boone), induced by white spot syndrome virus (WSSV) have occurred in Ecuador since May 1999. Three epidemiological surveys in Ecuadorian farms were carried out and showed an apparent association between lower temperature and increased mortality rates...

Full description

Saved in:
Bibliographic Details
Published in:Journal of fish diseases 2003-08, Vol.26 (8), p.439-450
Main Authors: Rodríguez, J, Bayot, B, Amano, Y, Panchana, F, De Blas, I, Alday, V, Calderón, J
Format: Article
Language:English
Subjects:
Animals
Cold Temperature
Ecuador
epidemiology
histopathology
Litopenaeus vannamei
Lymphoid Tissue - ultrastructure
Marine
Microscopy, Electron
Odds Ratio
Penaeidae - virology
Penaeus vannamei
Seasons
ultrastructure
Virus Diseases - mortality
Virus Diseases - pathology
Virus Diseases - veterinary
White spot syndrome virus
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Mortalities of cultured shrimp, Penaeus vannamei (Boone), induced by white spot syndrome virus (WSSV) have occurred in Ecuador since May 1999. Three epidemiological surveys in Ecuadorian farms were carried out and showed an apparent association between lower temperature and increased mortality rates in commercial ponds. Infected animals showed a reddish discolouration and lethargy and occasionally, white spots in the exoskeleton. Histopathological studies revealed that infected cells presented nuclear hypertrophy with eosinophilic to basophilic inclusions. In some cases, two other pathologies were observed: (a) lymphoid organ spheroids and (b) cells with pyknotic and karyorrhectic nuclei in the lymphoid organ, haematopoietic tissue, connective tissue, heart and antennal gland. Occasionally pyknotic cells were encapsulated without apparent injury to the adjacent tissue and without melanization. Transmission electron microscopy showed the presence of WSSV particles in the cytoplasm of cells with pyknotic nuclei in the stomach hypodermis. Viral structure and morphogenesis agreed with previous descriptions by other authors in WSSV‐infected shrimp. Occasionally, two nucleocapsids within one envelope were present amongst single enveloped nucleocapsids. A long rod‐shaped structure that could reach 2.4 μm in length was present in the nuclei of some infected cells.
ISSN:0140-7775
1365-2761
DOI:10.1046/j.1365-2761.2003.00483.x