Implications of white spot syndrome virus disease on DNA integrity, histology and biochemistry of Procambarus clarkii in Egypt

White spot syndrome virus (WSSV) is a widespread and highly pathogenic virus; that infects shrimp, crayfish and other crustaceans. The objectives of the present study were to investigate WSSV implications on some crayfish tissues, within light and sever stages of infections. Several parameters have been investigated including DNA integrity, oxidative stress, and histological changes in gills, muscles and hepatopancreas cells, using several techniques such as comet assay, DNA fragmentation assay, oxidative stress biomarkers estimation and histopathological examination. Specimens were divided into three groups according to the nested PCR results. Group I included healthy specimens whose tissues were all negative two-step PCR; Group II involved lightly infected specimens with positive two-step PCR. Group III included heavily infected specimens whose tissues were tested mostly positive one-step PCR. WSSV generates an increase in the different parameters of DNA damage (P 0.05) with abnormal histological features and notable reduction (P 0.05) of the endogenous scavengers in the tested tissues of the infected crayfish in comparison with the normal healthy ones. Furthermore, gills were found to be the most affected organ followed by muscle and finally hepatopancreas. These outcomes additionally demonstrated that comet test could profitably be utilized in genotoxicity evaluation protocols in aquatic invertebrates.