Susceptibility of farmed juvenile giant grouper Epinephelus lanceolatus to a newly isolated grouper iridovirus (genus Ranavirus).
A ranavirus was isolated from the diseased farmed groupers (Grouper iridovirus in genus Ranavirus, GIV-R), Epinephelus hybrids (blotchy rock cod, Epinephelus fuscoguttatus ♀×giant grouper, Epinephelus lanceolatus ♂), in Sanya, Hainan, in July 2013. In this study, susceptibility of farmed juvenile giant grouper E. lanceolatus to GIV-R was determined by intraperitoneally injection. The cumulative mortality reached to 81% at 5 day post infection. Histologically, severe degeneration with massive pycnotic nuclei in spleen and kidney tissues was observed, and some small-size inclusion body-bearing cells (IBCs) existed in spleen. Hemorrhage and infiltration of inflammatory cells were presented in gill, liver and heart along with tissue degeneration and necrosis of varying severity. The results of immunohistochemistry analysis showed that the strongest immunolabellings were obtained from the kidney and spleen tissues, while intermediate intensity signals were observed in the heart, stomach, gill and liver tissues, and the weakest signals were obtained from the intestine and brain, but no signal was obtained in eyes. Electron microscopy revealed that spleen of moribund fish contained many viral particles in cytoplasm. Interestingly, in surviving fish, abnormal hypertrophic cells were observed in both splenic corpuscle and renal corpuscle, while no hypertrophic cell was observed in the other parts of spleen and kidney tissues. Moreover, immunolabellings only stained the hypertrophic cells in splenic corpuscle and renal corpuscle. This indicated that splenic corpuscle and renal corpuscle play an important role in GIV-R infection and replication.
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China.
Chao
C
Peng
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China.
Hongling
H
Ma
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China.
Youlu
Y
Su
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China.
Weigeng
W
Wen
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China.
Juan
J
Feng
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China.
Zhixun
Z
Guo
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, The South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, PR China. Electronic address: qiu902@126.com.
Lihua
L
Qiu
D000818:Animals; D004266:DNA Virus Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D004198:Disease Susceptibility; D005393:Fish Diseases / Q000276:immunology* / Q000473:pathology / Q000821:virology; D005880:Gills / Q000473:pathology; D007150:Immunohistochemistry / Q000662:veterinary; D007668:Kidney / Q000473:pathology / Q000821:virology; D008099:Liver / Q000473:pathology; D008854:Microscopy, Electron / Q000662:veterinary; D009336:Necrosis; D010473:Perciformes; D017995:Ranavirus; D013154:Spleen / Q000473:pathology / Q000648:ultrastructure / Q000821:virology
Epinephelus lanceolatus; Histopathology; Immunohistochemistry; Ranavirus