Susceptibility of juvenile humpback grouper Cromileptes altivelis to grouper sleepy disease iridovirus (GSDIV).
Susceptibility of juvenile humpback grouper Cromileptes altivelis to the grouper sleepy disease iridovirus (GSDIV) was examined. GSDIV-containing inocula for challenge were obtained using a filtrate of spleen tissues from donor fish (orange-spotted grouper Epinephelus coioides) infected with GSDIV. Groups injected with the primary filtrate showed lower mortalities (30 to 60%) than groups receiving the 10(-4) diluted inoculum (90 to 100% mortality). This result was contrary to the expectation that fish challenged with a higher concentration of virus would show higher mortality. Electron microscopy revealed that moribund fish receiving the 10(-4) diluted inoculum displayed massive formation of typical inclusion body-bearing cells (IBCs) containing an intracytoplasmic inclusion body with many virions in the 180-200 nm size range propagated within a virus assembly site. In contrast, survivors in fish receiving the primary filtrate showed the formation of unusual IBCs containing an abnormal inclusion body that was characterized by the assembly of a small number of deformed virions. This impaired virus assembly appeared to prevent mortality in the challenged fish and was assumed to be due to an interferon-like effect of a previously unknown substance that was passed on to the challenged fish with the tissue filtrate from the donor fish.
Mahardika
Ketut
K
Gondol Research Institute for Mariculture, PO Box 140, Singaraja, Bali, Indonesia.
Zafran
Yamamoto
Asami
A
Miyazaki
Teruo
T
D000818:Animals; D004266:DNA Virus Infections / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D004198:Disease Susceptibility / Q000662:veterinary* / Q000821:virology; D020920:Dyssomnias / Q000662:veterinary* / Q000821:virology; D005393:Fish Diseases / Q000821:virology*; D007181:Inclusion Bodies, Viral / Q000648:ultrastructure*; D007497:Iridoviridae; D008854:Microscopy, Electron; D010473:Perciformes; D013154:Spleen / Q000648:ultrastructure / Q000821:virology