Biological Control of Fish Viral Diseases by Anti-Viral Substance Producing Bacteria.

Abstract

Many bacteria producing anti-viral substances were isolated from the aquatic environment. Fish intestinal bacteria such as Aeromonas spp. and Vibrio spp. producing anti-viral substances were isolated from intestinal contents of masu salmon (Oncorhynchus masou), Japanese flounder (Paralichthys olivaceus) and barfin flounder (Verasper moserr). These Aeromonas strains produced anti-infectious hematopoietic necrosis virus (IHNV) substances and Vibrio strains showed anti-IHNV, Oncorhynchus masou virus (OMV) and barfin flounder nervous necrosis virus (BF-NNV) activities. When Aeromonas spp. strains M-26 and M-38 were mixed with food pellets and fed to rainbow trout (O, mykiss) and masu salmon, both bacteria became dominant in the intestinal microflora and anti-IHNV activity was observed in homogenates of intestinal contents. These rainbow trout and masu salmon fed the Aeromonas spp. showed more resistance to the artificial IHNV challenge test. Barfin flounder fed Vibrio sp. strain 2IF6a with Altemiasalina showed the anti-OMV and BF-NNV activities in the intestinal contents. Larvae fed the Vibrio sp. showed a higher survival rate than the fish cultured using the virus free sea water.

Survival of Koi Herpesvirus (KHV) in Environmental Water

“…Actually 5.7% of isolated bacteria from environmental T-1; Tsurumi River December, 2.5 < 1.8 * 1 < 1.8 < 1.8 NT * 2 T-2; Tsurumi River 2004 2.5 < 1.8 * 1 < 1.8 < 1.8 NT T-3; Tsurumi River 2.5 < 1.8 * 1 < 1.8 < 1.8 NT T-4; Ookuma River 2.5 < 1.8 * 1 < 1.8 < 1.8 NT T-5; Onda River 2.5 < 2.1 < 1.8 * 1 < 1.8 NT T-6; Asabu River 2.5 < 2.1 < 2.1 < 1. water showed anti-KHV activity. We have reported that many bacteria showing anti-viral activity were isolated from fish rearing water and played an important role in the microbial ecosystem (Yoshimizu et al, 1976;Kamei et al, 1987Kamei et al, , 1988aKimura et al, 1990;Yoshimizu and Ezura, 1999). Anti-viral mechanisms of the bacteria isolated from Tsurumi River and from Goryokaku are unknown, but these bacteria were assumed to produce anti-viral substances that reduce of KHV infectivity.…”

New RT-qPCR assay for viral nervous necrosis virus detection in sea bass, Dicentrarchus labrax (L.): application and limits for hatcheries sanitary control

“…4). This inhibition was probably due to the presence of reverse transcriptase and/or polymerase inhibitor in water produced by this biological filter or by bacteria present in this biological filter, such as Vibrio or Pseudomonas which antiviral property has previously been described in fresh water salmonidae hatcheries [17,18]. Secondly, bypassing the UV and the biological filters, in order to avoid virus destruction, gave us the opportunity to observe the transmission of VNNV V26 in water.…”

Probiotics and Other Microbial Manipulations in Fish Feeds

“…Reciprocally, the screening of bacteria capable to inhibit fish viruses was investigated (Kamei et al, 1987). are active against the infectious hematopoietic necrosis virus, and salmonids fed with these bacteria showed an improved resistance to the viral infection in experimental challenges (see reviews by Yoshimizu and Ezura, 1999;Maeda, 2004). are active against the infectious hematopoietic necrosis virus, and salmonids fed with these bacteria showed an improved resistance to the viral infection in experimental challenges (see reviews by Yoshimizu and Ezura, 1999;Maeda, 2004).…”