We examined the distribution of iridoviruses in 10 freshwater ornamental fish species hatched in Korea and imported from other Asian countries using both 1-step and 2-step polymerase chain reation (PCR). None of the 10 fish species analyzed were free of iridovirus as shown by 2-step PCR positive results, and 3 species yielded 1-step PCR positive results with associated mortality. Cloned PCR amplicons of the adenosine triphosphatase (ATPase) and major capsid protein (MCP) genes in genomic DNA of iridovirus showed the same nucleotide sequences as that of infectious spleen and kidney necrosis virus (ISKNV) isolated from the mandarinfish Siniperca chuatsi. These results indicate the presence of ISKNV disease in various ornamental fish as new host species and that the disease is widespread throughout different Asian countries including Korea, Singapore and China. Such infections were either clinical with associated mortality (and 1-step PCR positive) or asymptomatic in fish that were externally healthy (and only positive in 2-step PCR). Molecular analyses of the K2 region performed on iridovirus samples isolated from freshwater ornamental fishes revealed deletion/insertion of repetitive sequences of various lengths (42 to 339 bp), depending on the ISKNV isolates, without substitutions. Experimental infection of pearl gourami Trichogaster leeri and silver gourami T. microlepis with a tissue homogenate of pearl gourami infected by ISKNV induced 70 and 20% cumulative mortalities in the pearl and silver gourami, respectively. KEY WORDS: Iridovirus · ISKNV · Ornamental fish · Asymptomatic infection · Asian countries Resale or republication not permitted without written consent of the publisherDis Aquat Org 78: [209][210][211][212][213][214][215] 2008 (ALIV) and dwarf gourami C. lalia iridovirus (DGIV) in Japan.Infectious spleen and kidney necrosis virus (ISKNV), recently assigned to the new Megalocytivirus genus of the Iridoviridae family, based on morphological and genetic characteristics (Chinchar et al. 2005), has caused significant economic loss in the mandarinfish Siniperca chuatsi aquaculture sector of China (He et al. 2000). In studies to elucidate the transmission and host range of ISKNV, mandarinfish appears to be the only species infected naturally and the most susceptible species, followed by largemouth bass in experimental infections of 21 fish species tested (He et al. 2002). In addition, the presence of ISKNV has only been reported in China. Jeong et al. (2006a), using 2-step polymerase chain reation (PCR), reported megalocytivirus in marine fish species that were externally healthy, a condition that could be called persistent or asymptomatic infection. Moreover, investigation of largemouth bass Micropterus salmoides salmoides, using a 1-step PCR technique after the occurrence of mass mortality, has also revealed the long-term persistence of ranavirus, largemouth bass virus (LMBV), in the population (Hanson & Petrie-Hanson 2001).Although Megalocytivirus and Ranavirus are epidemiologically and g...

The functional B cell repertoire in BALB/c mice was assessed at various stages in ontogeny. This was done by analyzing VH gene family expression using the sensitive technique of in situ hybridization. The B cell repertoire was probed with the mitogen, LPS, and the antigen DNP. DNP was chosen because B cells responsive to this hapten appear very early in ontogeny. The APCs that developed after stimulation with LPS or DNP were analyzed for VH gene expression by in situ hybridization of individual cells using radiolabeled VH gene family probes. The results indicated that VH gene expression in fetal B cells after stimulation was distinct from adult B cells in that there was a biased expression of D proximal families. The results indicated that this bias was associated with developmental age and not a given differentiation stage in the B cell lineage. In addition, stimulation of fetal B cells with DNP resulted in a large increase in expression of member(s) of VH 36-60, suggesting that the early appearance of DNP-responsive B cells is not strictly correlated with preferential rearrangement of D proximal families, VH 7183 and VH Q52. However, the results suggested that a large proportion of pre-B cells that preferentially rearrange D proximal families early in ontogeny become part of the functional developing repertoire.

No abstract

No abstract

No abstract

No abstract

No abstract

Effects of synthetic cytidine-phosphate-guanosine (CpG) oligodeoxynucleotide (ODN) on respiratory burst activity of olive flounder (Paralichthys olivaceus) head-kidney phagocytes and on protection against lethal infection with Edwardsiella tarda were investigated. Phagocytes precultured with a CpG ODN showed significantly higher chemiluminescence (CL) responses than phagocytes precultured with guanosine-phosphate-cytidine (GpC) ODN or culture medium alone (control) at all concentrations. Supernatants produced from leucocytes, which were pulsed with CpG ODN, induced significantly higher respiratory burst activity than supernatants produced by GpC ODN or culture medium alone. In an in vivo experiment, respiratory burst activities of the head kidney phagocytes in the groups injected either 0.25 or 0.5 µg fish -1 of CpG ODN were significantly higher than those in the groups injected with GpC ODN or HBSS (control) at 3, 5 and 7 d after injection. The groups of fish injected with 0.25 or 0.5 µg of CpG ODN showed higher survival rates (83.3%) than groups treated with GpC ODN (33.3%) and a control group (8.3%) after challenge with E. tarda. The present in vitro and in vivo experiments have demonstrated the ability of synthetic CpG ODN to increase phagocyte respiratory burst activity and disease resistance in olive flounder.