Histopathology and cytopathology of white spot syndrome virus (WSSV) in cultured Penaeus monodon from peninsular Malaysia with emphasis on pathogenesis and the mechanism of white spot formation

Abstract

ABSTRACT-Since 1994, white spot syndrome virus [WSSV) has been detected in cultured shrimp Penaeus monodon in Peninsular Malaysia. The gross signs, target organs and histo-cytopathology for the viral infection were studied and it was found to infect most organs and tissues including oocytes, but not hepatopancreatocytes and epithelia1 cells of the midgut, which were regarded as refractory tissues. Based on a time-sequence of ultrastructural cytopathology, 4 cytopathic profiles and 6 phases of viral morphogenesis were described. The virions were elliptical to short rods with trilamilar envelopes that measured 305 T 30 X 127 k l 1 nm. Viral nucleosomes were often present singly in infected nuclei and were associated with the early stages of viral replication. The structure of WSSV pathognomonic white, cuticular lesions was examined at the microscopic and ultrastructural levels and the mechanism of their formation appeared to be related to the disruption of exudate transfer from epithelial cells to the cuticle via cuticular pore canals.

Pathological changes in Fenneropenaeus indicus experimentally infected with white spot virus and virus morphogenesis

“…Therefore, it could be reasonably inferred that collapse of the supportive connective tissue was responsible for the profound pathological changes of hepatopancreatic tubules; nevertheless, they themselves were not susceptible to the virus. This result agrees with the studies done in P. monodon Wang et al, 1999) and L. vannamei (Escobedo-Bonilla et al, 2007) which revealed virus replication in the myoepithelial cells of the hepatopancreatic sheath and cells of the connective tissues but not in the hepatopancreatic tubular epithelial cells.…”

“…At least 18 cultured and/or wild penaeid shrimp (Park et al, 1998), eight caridean species (Pramod-Kiran et al, 2002), seven species of lobster (Rajendran et al, 1999), seven species of crayfish (Edgerton, 2004), 38 crab species (Yoganandhan et al, 2003) six non-decapod crustacean species (Hossain et al, 2001), members of the phyla Chaetognata and Rotifera (Yan et al, 2004), polychaete worms (Supak et al, 2005) and some aquatic insect larva (Ramírez-Douriet et al, 2005) have been found susceptible to the virus. Histopathological observations during WSV infection in brief is available regarding shrimp species such as Penaes monodon (Durand et al, 1997;Wang et al, 1999Wang et al, , 2000Mishra and Shekhar, 2005) Litopenaeus vannamei and Marsupenaeus japonicus (Lu et al, 1997;Lightner et al, 1998;Escobedo-Bonilla et al, 2007;Perez et al, 2005;Pantoja and Lightner, 2003), species of Crabs (Kanchanaphum et al, 1998;Kou et al, 1998) and lobster (Rajendran et al, 1999;Wang et al, 1998;Jiravanichpaisal et al, 2001).…”

“…Since its advent in 1992, WSV has greatly affected the shrimp farming industry (Mohan et al, 1997). This pathogen has tropism for organs of mesodermal and ectodermal origin (Wongteerasupaya et al,1995(Wongteerasupaya et al, , 1996Chang et al, 1996;Flegel et al, 1997;Rajendran et al, 1999;Wang et al, 1999;Vijayan et al, 2003;Yoganandhan et al, 2003). Evidence of histopathological manifestations in the target tissues is one of the criteria used in the diagnosis of WSV infection (Lightner, 1996;Wang et al, 1997).…”

TRBP Homolog Interacts with Eukaryotic Initiation Factor 6 (eIF6) in Fenneropenaeus chinensis

“…The WSSV inoculum was prepared according to a previously described method (20). WSSV was extracted from the gills of naturally infected F. chinensis and stored at Ϫ80°C.…”

Examination for Viral Inactivation of WSSV (White Spot Syndrome Virus) Isolated in Malaysia Using Black Tiger Prawn (Penaeus monodon)

“…Features of this white spot syndrome (WSS) are that the diseased prawns often show obvious white spots on their carapace and that a high mortality occurs from 80% to 100% in only a few days after infection 1 . In the case of Malaysia, WSS was reported in 1994 and at almost the same period in Thailand 13,16 . WSS spread rapidly in peninsular Malaysia, and since 1996 this disease has caused enormous economic losses against the prawn culture industry in Malaysia.…”