Infectivity of aquabirnavirus strains to various marine fish species

Abstract

To determine the infectivity of marine birnavirus (MABV) in various marine fish species, experimental infection was performed in combination groups of 5 fish species with 7 strains of MABV and 1 strain of infectious pancreatic necrosis virus (IPNV). Mortality was observed in yellowtail Seriola quinqueradiata and amberjack S. dumerili infected with MABV strains Y-6, Y-10K and H-1, but not in other infected species. MABV was reisolated from most combination groups, but the virus isolation rate and virus infectivity titer were often significantly different among groups with the same fish species or with the same virus strain. All MABV strains replicated well in makogarei Limanda yokohamae, but only slightly in tiger puffer Takifugu rubripes. IPNV also replicated in all fish species without causing death. The isolation rate and infectivity titer of IPNV were similar to or higher than those of non-virulent strains of MABV. In conclusion, the infectivity of MABV for different fish species is considered to change, which is an important factor in the development of the infection cycle of this virus among marine organisms. KEY WORDS: Aquabirnavirus · Marine birnavirus · Infectious pancreatic necrosis virus · Marine fish · Infectivity · Experimental infection Resale or republication not permitted without written consent of the publisherDis Aquat Org 46: [109][110][111][112][113][114] 2001 We report the infectivity of several aquabirnavirus strains, including MABV and IPNV, against some marine fish species. The mortality, virus isolation rate and infectivity titer were compared among experimental groups. MATERIALS AND METHODSCell line. The CHSE-214 cell line (chinook salmon embryo; Lannan et al. 1984) was used in this study. This cell line was grown at 20°C in Eagle's minimum essential medium (Nissui, Japan) supplemented with 10% fetal bovine serum.Virus strains. The aquabirnavirus strains used in this study are shown in Table 1. Seven strains of MABV and 1 strain of IPNV isolated from fish and shellfish cultured in various areas of western Japan during natural outbreaks were examined. Among them, an unpublished strain, KMKBV-9701, was isolated from hatchery-reared makogarei Limanda yokohamae juveniles (27 d old, average 10 mm in total length) collected during mass mortalities at a water temperature of 15°C in February 1997 in Kagawa Prefecture. Each strain was grouped into MABV or IPNV by genogrouping based on amino acid sequences in the VP2/NS junction region (Hosono et al. 1996). All these strains were propagated on CHSE-214 cells at 20°C. The susceptibility of the CHSE-214 cell line at 20°C was nearly equal to all the used virus strains (data not shown).Experimental fish. Five species of marine fish were examined: yellowtail (mean body weight 2.2 g), amberjack Seriola dumerili (17.7 g), black sea bream, Acanthopagrus schlegeli (6.6 g), tiger puffer (3.0 g) and makogarei (6.2 g). These fishes were produced at Yashima Station of Japan Sea-Farming Association, Kagawa Prefectural Sea-Farming Center, or a priva...

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

“…Although all specimens showed no symptoms of viral infection, ABVs were detected regardless of host fish species. MABV can infect various fish species without clinical signs with relatively low virus titers in the infected fish (23). Our results showed that some fish with no symptoms have ABVs at a comparatively high concentration.…”

Detection and Genetic Analysis of Aquabirnaviruses in Subclinically Infected Aquarium Fish

“…12 Such a quarantine system could be implemented in conjunction with RT-PCR testing of the sentinel fish or of some of the new arrivals, similar to what was done in the current study. Only after the batch of fish has been determined to be free of ABV infection, would the fish be released into the general population.…”

“…19 Because any fish in the aquarium can potentially carry pathogens, preventive steps should be taken. Thus, it is recommended that aquariums quarantine all new arrivals with specific pathogen-free (SPF) sentinel fish, such as makogarei (or marbled flounder, Pseudopleuronectes yokohamae) or yellowtail, which are susceptible to MABV, 12 before transferring the new arrivals to the display.…”

Solar UV radiation does not inactivate marine birnavirus in coastal seawater

“…MABV was first isolated from diseased yellowtail Seriola quiqueradiata in Japan in 1985 (Sorimachi & Hara 1985). Similar birnaviruses have been isolated from shellfish and other cultured and wild fish from around the world (Sohn et al 1995, Cutrin et al 2000, Isshiki et al 2001). Many of the birnavirus isolates were genetically similar , suggesting that all isolates belong to the MABV group.…”

“…Many of the birnavirus isolates were genetically similar , suggesting that all isolates belong to the MABV group. MABVs have a broad host range in various marine organisms (Cutrin et al 2000, Isshiki et al 2001.…”