Molecular Characterization and Gene Expression Profiling ... - CUSAT

Chapter 1
of the shrimp cephalothorax or carapace (Fig.1.3). Abnormal deposits of
calcium, the accumulation of vacuoles and lysed debris and the necrosis of
cuticular pore canals produce white spots on the cuticular epidermis (Wang
et al., 1995; Lightner, 1996). Not all shrimps infected with WSSV display
white spots on the carapace (Lightner, 1996). Affected animals also display
expanded chromatophores that show a pink-red to reddish-brown coloration
in the cephalothorax cuticle (Inouye et al., 1996). Diseased shrimp exhibit a
reduction in feeding and increased lethargy. Infected shrimp swim slowly
near the pond surface and eventually sink to the bottom and die (Chang et
al., 1996, 1998; Lightner, 1996; Wang et al., 1999).
Fig. 1.3. The clinical sign of white spot disease in an infected shrimp
WSSV can infect cells of mesodermal and ectodermal origin, such as
the subcuticular epithelium, the lymphoid organ, haemocytes,
haematopoietic tissue, stomach cuticular epidermis and connective tissue
(Momoyama et al., 1995; Lightner, 1996). Infected tissues display widespread
focal necrosis (Wongteerasupaya et al., 1995). Degenerate cells are
characterised by hypertrophied nuclei with marginated chromatin and
eosinophilic to basophilic intranuclear inclusions (Chou et al., 1995;
Wongteerasupaya et al., 1995). Haemocytic encapsulation of necrotic cells as
Molecular Characterization and Gene Expression Profiling of Antimicrobial Peptides in Penaeid Shrimps
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