Replication and pathogenesis of white sturgeon iridovirus (WSIV) in experimentally infected white sturgeon Acipenser transmontanus juveniles and sturgeon cell lines

Abstract

Characteristics of the In vitro propagation of the white sturgeon iridovirus (WSIV) were examined in 6 sturgeon cell lines. One new cell line originating from gonadal tissues (WSGO) produced up to 12-fold more WSIV 1-22 TCID,, (50% tissue culture infective dose) cell-L] than that of a previously established reference spleen cell line (WSS-2). Infected WSGO cell cultures were examined using phase microscopy, viral infectivity assay and transmission electron microscopy (TEM). At 15OC, both mature virions and infectious virus were first detected after 7 d post-infection. Caps~ds acquired envelopes in the cytoplasm and virions remained pnmanly cell-associated during the 35 d replication cycle. Cellular changes including hyper-refractility and cytoplasmic swelling with dense cytoplasmic inclusions correlated to extenslve proliferation of cytoplasmic vesicles and viral assembly sites. These cytological characteristics corresponded to changes in target cells of WSIV-infected juvenile white sturgeon following bath challenge. Microscopic changes in stained tissue sections of the host epithelium were detected 4 d post-challenge, approximately 8 d prior to the onset of clinical signs. Hypertrophied Malpighian cells surrounded by a prominent pericellular cisternum characterized epithelia1 lesions in the skin. Similar changes to epithehal cells of the barbels, olfactory organs and esophagus were also observed. Destruction of the sensory epithelium is suggested as a cause for cessation of feeding which occurs early in the Infection of white sturgeon juveniles with WSIV.

Histological, ultrastructural, and in situ hybridization study on enlarged cells in grouper Epinephelus hybrids infected by grouper iridovirus in Taiwan (TGIV)

“…The distribution of chromatin in a TGIV-infected cell is different from that in an FV3-infected cell, and is not arranged along the inner nuclear membrane as with FV3 (Kelly 1975). Although the pathology of WSIV infection includes cell hypertrophy, it does not reach the same extent as in TGIV infection (Watson et al 1998). Also, the unique ultrastructural feature, the concentrically arranged double-unit membrane structure in the viral assembly site of WSIV (Watson et al 1998), was not seen in TGIV-infected fish.…”

“…Although the pathology of WSIV infection includes cell hypertrophy, it does not reach the same extent as in TGIV infection (Watson et al 1998). Also, the unique ultrastructural feature, the concentrically arranged double-unit membrane structure in the viral assembly site of WSIV (Watson et al 1998), was not seen in TGIV-infected fish. In RSIV-infected red sea bream, enlarged cells contain prominent inclusion bodies and are described as 'inclusion body bearing cells (IBCs)' .…”

Characterization of an iridovirus from the cultured pig frog Rana grylio with lethal syndrome

“…Iridoviruses have been isolated from amphibian (Granoff et al 1966, Essani & Granoff 1989, Speare & Smith 1992, Alves de Matos & Paperna 1993, Hengstberger et al 1993, Zupanovic et al 1998a,b, Bollinger et al 1999 and fish hosts (Ahne et al 1989, 1997, Essani & Granoff 1989, Hedrick et al 1992, Hedrick & McDowell 1995, Granzow et al 1997, Tapiovaara et al 1998, Watson et al 1998, Whittington et al 1999) and have been associated with high mortality in some species (Langdon et al 1986, 1988, Fijan et al 1991, Cullen et al 1995, Matsuoka et al 1996, Rodger et al 1997, Kanchanakhan 1998, McGrogan et al 1998. For example, epizootic hematopoietic necrosis virus (EHNV), first isolated in Victoria, Australia, is responsible for large-scale mortalities in redfin perch Perca fluviatilis due to necrosis of hepatic, splenic, pancre-atic, and renal hematopoietic tissues.…”

Ultrastructural morphogenesis of a virus associated with lymphocystis-like lesions in parore Girella tricuspidata (Kyphosidae: Perciformes)

“…Others report the ultrastructure of the virions (Pearce et al 1990, Heppell & Berthiaume 1992. Those that do report other observations (Tanaka et al 1984, Paperna et al 1987, Watson et al 1998, Sudthong kong et al 2002, Huang et al 2006, Chinchar et al 2011, Chinchar & Waltzek 2014 do not report the process of replication. Most studies are on the late stages of replication because grossly hypertrophied cells have been chosen for study.…”