Virusinfektionen bei Fischen: Ätiologie, Diagnose und Bekämpfung

Establishment of caudal fin cell lines from tropical ornamental fishes Puntius fasciatus and Pristolepis fasciata endemic to the Western Ghats of India

Two new cell lines, PFF and CFF were established from the caudal fin of the Puntius fasciatus, and Pristolepis fasciata respectively. Since their initiation, these cell lines (PFF and CFF) have been subcultured in L-15 medium with 10% fetal bovine serum for more than 35 passages at 28°C and both the cell lines were characterized. Karyotyping analysis of PFF and CFF cells at 25th passage indicated that the modal chromosome number was 2n=50 and 2n=48 respectively. The cell line was cryopreserved in liquid nitrogen at -196°C and could be recovered from storage after six months with good cell viability. Polymerase chain reaction amplification of the fragments of two mitochondrial genes, 16S rRNA and COI confirmed that the cell lines originated from the respective species. The bacterial extracellular products from Vibrio cholerae MTCC3904 and Aeromonas hydrophila were found to be toxic to PFF and CFF. Both the cells were resistant to the marine viral nervous necrosis virus (VNNV). No CPE could be found in both cell lines inoculated with the fish samples and cell culture supernatants were demonstrated free of SVC, iridovirus and KHV by molecular methods. These results indicated the absence of SVC, iridovirus and KHV in the ornamental fishes collected from the Western Ghats of India.

Quantification of Aquabirnaviruses Isolated from Different Host Species by Real-Time RT-PCR

Real-time reverse transcription (RT)-PCR was developed to detect and quantify successfully aquatic birnaviruses (ABVs) from fish tissue and seawater samples. This method detected marine birnavirus (MABV) RNA in several samples, and the detection was specific for ABVs. Monitoring the MABV strain Y-6 RNA quantification by real-time RT-PCR showed replication kinetics of MABV after experimental infection in vitro. We found the quantity of ABVs isolated from different host species by using combined virus absorption in cell culture and real-time RT-PCR. Although all specimens showed no symptoms of viral infection, ABVs were detected regardless of host species. In conclusion, real-time RT-PCR was shown to be a sensitive and reliable tool to detect and quantify ABVs in cultured fish. This method is useful procedure to show details of horizontal or vertical infections by ABVs in the breeding water of aquatic animals.

Fish viruses: transmission and pathogenicity of an icosahedral cytoplasmic deoxyribovirus isolated from sheatfish (Silurus glanis)

An iridovirus-like agent which was isolated from sheatfish fry showed to be of high virulence to those fish. 100% of sheatfish fry infected by water bath died within 8 days. The agent could be transmitted by infected fish causing 100% mortality in 11 days. Moribund fry showed spiralic swimming and exhibited hemorrhages in the skin. The infection studies demonstrate that the isolated virus was responsible for a sudden epizootic in 1988 with 100% mortality occurring in a warm water recirculating aquaculture unit in Northwest Germany, regularly controlled by the State Fish Epidemics Control Service of Lower Saxony and Fish Health Service.

Fish viruses: isolation of an icosahedral cytoplasmic deoxyribovirus from sheatfish (Silurus glanis)

An icosahedral cytoplasmic deoxyvirus has been isolated from moribund sheatfish (Silurus glanis) fry of a commercial warm water recirculation aquaculture unit with cumulative mortalities of up to 100%. The agent replicated in BF-2 and in FHM cells at 20-30 degrees C producing cytoplasmatic inclusion bodies followed by lysis of the cells. The DNA containing virus proved to be labile to chloroform. Infected BF-2 cells revealed hexagonal particles in the cytoplasm measuring about 125-135 nm in diameter. The virus consisted of a central electron-dense core and a electron-translucent zone. The isolate shares characteristics with the Iridoviridae.