ELECTRON MICROSCOPIC STUDY ON ENLARGED CELLS OF RED SEA BREAM, Pagrus major INFECTED BY THE RED SEA BREAM IRIDOVIRUS (RSIV, GENUS Megalocytivirus, FAMILY Iridoviridae)

Most histopathologycal studies of the red sea bream iridovirus (RSIV) disease in red sea bream have been performed by studying enlarged cells as well as necrotized cells in the spleen and other organs. These enlarged cells have been named as inclusion body bearing cells (IBCs). However, few information is available about detail of ultrastructural features of IBCs produced in the target organs of RSIV-infected fish. In the present study, details of ultrastructural features of IBCs that were produced in the spleen tissue of naturally RSIV-infected red sea bream were investigated under electron microscope. Under electron microscope, RSIV-infected red sea bream had the presence of two types of IBCs: typical IBCs allowing virus assembly within viral assembly site (VAS), and atypical IBCs which degenerate organelles without virus assembly. Other infected-cells were observed as necrotized cells forming intracytoplasmic VAS with large numbers of virions, but without the formation of the distinct inclusion body. Morphogenesis steps on RSIV-infected red sea bream were observed as filamentous-filed virions, partially-filled virions and complete virions with 145-150 nm in size. These findings confirmed that RSIV-infected red sea bream were characterized by formation of typical and atypical IBCs as well as necrotized cells.

Download Full-text

Electron Microscopic Studies on Black Lines Appearing in Muscle Tissues of Cultured Red Sea Bream Pagrus major.

NIPPON SUISAN GAKKAISHI ◽

10.2331/suisan.58.1653 ◽

1992 ◽

Vol 58 (9) ◽

pp. 1653-1658 ◽

Cited By ~ 4

Author(s):

Kuniko Wakazono ◽

Yasuo Okajima ◽

Masataka Shirai ◽

Chikara Kitajima ◽

Seiichi Matsui ◽

...

Keyword(s):

Red Sea ◽

Sea Bream ◽

Red Sea Bream ◽

Pagrus Major ◽

Electron Microscopic ◽

Muscle Tissues ◽

Microscopic Studies

Download Full-text

Pathogenicity of Iridovirus from Japan and Thailand for the Red Sea Bream Pagrus major in Japan, and Histopathology of Experimentally Infected Fish

Fisheries Science ◽

10.2331/fishsci.63.735 ◽

1997 ◽

Vol 63 (5) ◽

pp. 735-740 ◽

Cited By ~ 21

Author(s):

Sungju Jung ◽

Teruo Miyazaki ◽

Masato Miyata ◽

Yaowanit Danayadol ◽

Shinji Tanaka

Keyword(s):

Red Sea ◽

Infected Fish ◽

Sea Bream ◽

Red Sea Bream ◽

Pagrus Major

Download Full-text

Isolation and characterisation of an ISKNV-genotype megalocytivirus from imported angelfish Pterophyllum scalare

Diseases of Aquatic Organisms ◽

10.3354/dao03499 ◽

2020 ◽

Vol 140 ◽

pp. 129-141

Author(s):

Y Kawato ◽

PG Mohr ◽

MStJ Crane ◽

LM Williams ◽

MJ Neave ◽

...

Keyword(s):

Whole Genome Sequencing ◽

Genome Sequencing ◽

Red Sea ◽

Sea Bream ◽

Whole Genome ◽

Red Sea Bream ◽

Capsid Protein Gene ◽

Infected Cells ◽

Clade 1 ◽

Pterophyllum Scalare

Using cultures of the SKF-9 cell line, megalocytivirus AFIV-16 was isolated from imported angelfish Pterophyllum scalare held in quarantine at the Australian border. The cytopathic effect caused by isolate AFIV-16 presented as cell rounding and enlargement, but complete destruction of the infected cell cultures did not occur. The infected cells demonstrated immunocytochemical reactivity with monoclonal antibody M10, which is used for diagnosis of OIE-listed red sea bream iridoviral disease. Using electron microscopy, the virus particles, consisting of hexagonal nucleocapsids, were observed in the cytoplasm of SKF-9 cells. The replication of AFIV-16 in cultured SKF-9 cells was significantly greater at 28°C incubation than at 22 and 25°C incubation, whereas no difference in growth characteristics was observed for red sea bream iridovirus (RSIV) isolate KagYT-96 across this temperature range. Whole genome sequencing demonstrated that AFIV-16 has a 99.96% similarity to infectious spleen and kidney necrosis virus (ISKNV), the type species in the genus Megalocytivirus. AFIV-16 was classified into ISKNV genotype Clade 1 by phylogenetic analysis of the major capsid protein gene nucleotide sequence. This is the first report of whole genome sequencing of an ISKNV genotype megalocytivirus isolated from ornamental fish.

Download Full-text

ULTRASTRUCTURAL ANALYSIS OF GRUNT FIN (GF) CELLS TREATED WITH RED SEA BREAM IRIDOVIRUS (RSIV; family Iridoviridae, genus Megalocytivirus) IN COMBINATIONS WITH INTERFERONS AND SPLENIC SUBSTANCES

Indonesian Aquaculture Journal ◽

10.15578/iaj.5.1.2010.19-28 ◽

2010 ◽

Vol 5 (1) ◽

pp. 19

Author(s):

Ketut Mahardika ◽

Teruo Miyazaki

Keyword(s):

Red Sea ◽

Virus Assembly ◽

Cell Types ◽

Sea Bream ◽

Interferon Α ◽

Type I ◽

Viral Titer ◽

Red Sea Bream ◽

Virus Propagation

The genus Megalocytivirus in the family of Iridoviridae encompasses isolate of red sea bream iridovirus (RSIV). In the present study, grunt fin (GF) cells were treated with red sea bream iridovirus (RSIV) in combinations with interferons (IFNs) and splenic substances. The viral titer in the combination with primary splenic substance was higher than the other combinations of 10-1 and 10-2 diluted splenic substances, and the positive control. The viral titer was not decreased by all combinations with recombinant murine interferon-α (rMuIFN-α), recombinant murine IFN-β (rMuIFN-β), and recombinant feline interferon-ω (rFeIFN-ω). Electron microscopy revealed inclusion body bearing cells (IBCs) and enlarged cells allowing virus propagation within the intracytoplasmic virus assembly site (VAS). Most were enlarged cells. These enlarged cells were divided into three cell types. Cells of Type II, which contained many mature virions within the VAS, were numerous in number in all treated cells. Cells of Type I allowing assembly of few virions and cells of Type III containing many immature viral particles were rather fewer in number. Their percentage was almost the same in all combinations with the splenic substances and IFNs. These results determined in in vitro treatment with IFNs did not prevent viral replication of RSIV, as well as the splenic substances which were derived from the RSIV-infected spleen of red sea bream did not contain any factors to disturb RSIV replication.

Download Full-text

Phenotypic Diversity of Infectious Red Sea Bream Iridovirus Isolates from Cultured Fish in Japan

Applied and Environmental Microbiology ◽

10.1128/aem.02255-08 ◽

2009 ◽

Vol 75 (11) ◽

pp. 3535-3541 ◽

Cited By ~ 31

Author(s):

Hajime Shinmoto ◽

Ken Taniguchi ◽

Takuya Ikawa ◽

Kenji Kawai ◽

Syun-ichirou Oshima

Keyword(s):

Red Sea ◽

Phenotypic Diversity ◽

Sea Bream ◽

Cell Culture Supernatant ◽

Red Sea Bream ◽

Virus Family ◽

Recent Emergence ◽

Infected Cells

ABSTRACT Megalocytivirus is causing economically serious mass mortality by infecting fish in and around the Pacific region of Asia. The recent emergence of many new iridoviruses has drawn attention to the marked taxonomic variation within this virus family. Most studies of these viruses have not included extensive study of these emergent species. We explored the emergence of red sea bream iridovirus (RSIV) on a fish farm in Japan, and we specifically endeavored to quantify genetic and phenotypic differences between RSIV isolates using in vitro and in vivo methods. The three isolates had identical major capsid protein sequences, and they were closely related to Korean RSIV isolates. In vitro studies revealed that the isolates differed in replication rate, which was determined by real-time quantitative PCR of viral genomes in infected cells and cell culture supernatant, and in cell viability, estimated by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay for infected cells. In vivo studies showed that the isolates exhibit different virulence characteristics: infected red sea bream showed either acute death or subacute death according to infection with different isolates. Significant differences were seen in the antigenicity of isolates by a formalin-inactivated vaccine test. These results revealed that variant characteristics exist in the same phylogenetic location in emergent iridoviruses. We suggest that this strain variation would expand the host range in iridoviral epidemics.

Download Full-text

Prevalence of red sea bream iridovirus among organs of Japanese amberjack (Seriola quinqueradiata) exposed to cultured red sea bream iridovirus

Journal of General Virology ◽

10.1099/vir.0.052902-0 ◽

2013 ◽

Vol 94 (9) ◽

pp. 2094-2101 ◽

Cited By ~ 14

Author(s):

Takafumi Ito ◽

Yasutoshi Yoshiura ◽

Takashi Kamaishi ◽

Kazunori Yoshida ◽

Kazuhiro Nakajima

Keyword(s):

Cell Culture ◽

Red Sea ◽

Experimental Infection ◽

Natural Infection ◽

Severe Disease ◽

Infected Fish ◽

Sea Bream ◽

Red Sea Bream ◽

Viral Dna ◽

Seriola Quinqueradiata

Red sea bream iridovirus (RSIV) is a representative of the genus Megalocytivirus which causes severe disease to aquaculture fish, mainly in Japan and South-east Asia. However, information to assess the viral kinetics of RSIV in fish is limited since reports on experimental infection by the immersion route, which is the natural infection route, are scarce. In this study, a method to evaluate the titre of RSIV was first developed. Experimental infections were continuously performed using RSIV cell culture as the inoculum to juvenile Japanese amberjack (Seriola quinqueradiata) (initial body weight 12.2 g) by immersion at three different concentrations. In addition, to investigate the prevalence of the virus among the organs of experimentally infected fish, viral DNA was measured at selected times by the real-time PCR method following viral inoculation by immersion. The developed titration method showed a 102 increase in sensitivity compared with the conventional method. We demonstrated that grunt fin cells can be used for continuous passage of RSIV. In the experimental infection, fish which were intraperitoneally injected with the RSIV cell culture or immersed with RSIV cell culture at 10−2 and 10−3 dilutions showed cumulative mortalities of 100 %. The results of measurements of the viral DNA of several organs from infected fish strongly suggest that the spleen is the target organ of RSIV in Japanese amberjack. Since the viral genome was detected from all the tested organs of two of five surviving fish which appeared to completely recover from the disease, it is suggested that these fish may become carriers.

Download Full-text

Further Observations on the Virus of Epizootic Diarrhea of Infant Mice. An Electron Microscopic Study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060568 ◽

1967 ◽

Vol 25 ◽

pp. 110-111

Author(s):

W. G. Banfield ◽

G. Kasnic ◽

J. H. Blackwell

Keyword(s):

Electron Microscope ◽

Infected Cell ◽

Microscopic Study ◽

Intestinal Epithelium ◽

Ultrastructural Study ◽

Osmium Tetroxide ◽

Lead Citrate ◽

Electron Microscopic ◽

Virus Particles ◽

Infected Cells

An ultrastructural study of the intestinal epithelium of mice infected with the agent of epizootic diarrhea of infant mice (EDIM virus) was first performed by Adams and Kraft. We have extended their observations and have found developmental forms of the virus and associated structures not reported by them.Three-day-old NLM strain mice were infected with EDIM virus and killed 48 to 168 hours later. Specimens of bowel were fixed in glutaraldehyde, post fixed in osmium tetroxide and embedded in epon. Sections were stained with uranyl magnesium acetate followed by lead citrate and examined in an updated RCA EMU-3F electron microscope.The cells containing virus particles (infected) are at the tips of the villi and occur throughout the intestine from duodenum through colon. All developmental forms of the virus are present from 48 to 168 hours after infection. Figure 1 is of cells without virus particles and figure 2 is of an infected cell. The nucleus and cytoplasm of the infected cells appear clearer than the cells without virus particles.

Download Full-text