Three virus isolates, RGV-9506, RGV-9807 and RGV-9808, were obtained from cultured pig frogs Rana grylio undergoing lethal infections. Previously, the first isolate, RGV-9506, was shown to be an iridovirus based on ultrastructural and morphological studies. In the present study, the original isolate, along with 2 recent ones, were more extensively characterized by experimental infection studies, histopathology, electron microscopy, serological reactivity, gel electrophoresis of viral polypeptides and DNA restriction fragments, PCR amplification, and nucleic acid sequence analysis of the major capsid protein (MCP) gene. The 3 isolates were shown to be identical to each other, and very similar to FV3, the type species of the genus Ranavirus (family Iridoviridae). These results suggest that RGV should be considered a strain of FV3, and indicate that FV3-like iridoviruses are capable of causing widespread, severe disease among cultured frogs. KEY WORDS: Rana grylio · Iridovirus · FV3 · Ranavirus · Viral disease Resale or republication not permitted without written consent of the publisherDis Aquat Org 48: [27][28][29][30][31][32][33][34][35][36] 2001 atic, and renal hematopoietic tissues. Moreover, although infection of redfin perch leads to high levels of mortality, EHNV infects other fish species with varying results (Langdon et al. 1986). In another example, localized die-offs of tiger salamanders Ambystoma tigrinum and largemouth bass Micropterus salmoides in North America have been linked to the presence of novel iridoviruses (Plumb et al. 1996, Jancovich et al. 1997, Bollinger et al. 1999. Finally, iridoviruses can infect not only different species within the same taxonomic class, but the same virus can infect animals from different classes (Mao et al. 1999a). Thus, an iridovirus isolated from the ornate burrowing frog Bohle iridovirus has been shown to cause mortality in barramundi fish following experimental infections (Moody & Owens 1994). The above observations indicate that iridoviruses infecting aquatic animals enjoy a worldwide distribution and are increasingly associated with serious disease (Ahne et al. 1997.Although some aspects of iridovirus biology have been examined (Willis et al. 1985, Hedrick et al. 1992, Zupanovic et al. 1998a,b, Bollinger et al. 1999, Mao et al. 1999a, additional work is needed to understand the ecology, epidemiology, and pathogenicity of iridovirus-host interaction. In this study, 3 RGV isolates linked to severe disease in cultured frogs were characterized by experimental infection, histopathology, electron microscopy, serological cross reactivity, gel electrophoresis of virion polypeptides and DNA restriction fragments, PCR amplification, and sequence analysis of the major capsid protein (MCP) gene. We found that the 3 isolates were essentially identical to each other and closely related to FV3. In view of this, it is likely that RGV is a strain of FV3. MATERIALS AND METHODSPreparation of RGV isolates. RGV isolates were prepared from tissues (liver, kidney and s...

Lymphocystis diseases in fish throughout the world have been extensively described. Here we report the complete genome sequence of lymphocystis disease virus isolated in China (LCDV-C), an LCDV isolated from cultured flounder (Paralichthys olivaceus) with lymphocystis disease in China. The LCDV-C genome is 186,250 bp, with a base composition of 27.25% G؉C. Computer-assisted analysis revealed 240 potential open reading frames (ORFs) and 176 nonoverlapping putative viral genes, which encode polypeptides ranging from 40 to 1,193 amino acids. The percent coding density is 67%, and the average length of each ORF is 702 bp. A search of the GenBank database using the 176 individual putative genes revealed 103 homologues to the corresponding ORFs of LCDV-1 and 73 potential genes that were not found in LCDV-1 and other iridoviruses. Among the 73 genes, there are 8 genes that contain conserved domains of cellular genes and 65 novel genes that do not show any significant homology with the sequences in public databases. Although a certain extent of similarity between putative gene products of LCDV-C and corresponding proteins of LCDV-1 was revealed, no colinearity was detected when their ORF arrangements and coding strategies were compared to each other, suggesting that a high degree of genetic rearrangements between them has occurred. And a large number of tandem and overlapping repeated sequences were observed in the LCDV-C genome. The deduced amino acid sequence of the major capsid protein (MCP) presents the highest identity to those of LCDV-1 and other iridoviruses among the LCDV-C gene products. Furthermore, a phylogenetic tree was constructed based on the multiple alignments of nine MCP amino acid sequences. Interestingly, LCDV-C and LCDV-1 were clustered together, but their amino acid identity is much less than that in other clusters. The unexpected levels of divergence between their genomes in size, gene organization, and gene product identity suggest that LCDV-C and LCDV-1 shouldn't belong to a same species and that LCDV-C should be considered a species different from LCDV-1.

c Pneumonia is one of the most prevalent Staphylococcus aureus-mediated diseases, and the treatment of this infection is becoming challenging due to the emergence of multidrug-resistant S. aureus, especially methicillin-resistant S. aureus (MRSA) strains. It has been reported that LysGH15, the lysin derived from phage GH15, displays high efficiency and a broad lytic spectrum against MRSA and that apigenin can markedly diminish the alpha-hemolysin of S. aureus. In this study, the combination therapy of LysGH15 and apigenin was evaluated in vitro and in a mouse S. aureus pneumonia model. No mutual adverse influence was detected between LysGH15 and apigenin in vitro. In animal experiments, the combination therapy showed a more effective treatment effect than LysGH15 or apigenin monotherapy (P < 0.05). The bacterial load in the lungs of mice administered the combination therapy was 1.5 log units within 24 h after challenge, whereas the loads in unprotected mice or mice treated with apigenin or LysGH15 alone were 10.2, 4.7, and 2.6 log units, respectively. The combination therapy group showed the best health status, the lowest ratio of wet tissue to dry tissue of the lungs, the smallest amount of total protein and cells in the lung, the fewest pathological manifestations, and the lowest cytokine level compared with the other groups (P < 0.05). With regard to its better protective efficacy, the combination therapy of LysGH15 and apigenin exhibits therapeutic potential for treating pneumonia caused by MRSA. This paper reports the combination therapy of lysin and natural products derived from traditional Chinese medicine. Staphylococcus aureus is a ubiquitous and zoonotic pathogen that causes high morbidity and mortality in a variety of diseases, ranging from skin and soft tissue infections to necrotizing pneumonia and overwhelming sepsis (1, 2). S. aureus pneumonia is one of the most prevalent S. aureus-mediated diseases and accounts for 13.3% of all invasive S. aureus infections (3). Treatment of S. aureus infection has become increasingly difficult, given the prevalence of multidrug-resistant S. aureus strains, especially the widespread existence of methicillin-resistant S. aureus (MRSA) strains (4). MRSA strains are typically resistant to multiple antibiotics, including gentamicin, erythromycin, fluoroquinolones, and ofloxacin, among others (5). There are also reports of vancomycin-resistant S. aureus (VRSA), raising serious concerns within the medical community (6-8). Therefore, there is an urgent need for novel therapeutic strategies that are efficient against this pathogen.Lysin, which is encoded by the phage (bacterial virus) genome at the end of the phage lytic life cycle to lyse the host cell, can rapidly and specifically lyse Gram-positive bacteria when exogenously applied (9). Because the bacterial cell wall is conserved and necessary for the life cycle, the current lack of bacterial resistance against lysin is not surprising (10). In addition, its species specificity or type specificity ensures that lysin w...

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Flavobacterium columnare is a Gram-negative bacterium causing columnaris disease of freshwater fish worldwide, and development of efficacious vaccines has been a continuous challenge in aquaculture. In this study, 14 proteins were identified from cellular components of F. columnare using an immunoblotting approach in two-dimensional electrophoresis map gels with antibacterial sera from grass carp, Ctenopharyngodon idella (Valenciennes), and then anti-grass carp-recombinant Ig (rIg) polyclonal antibodies. These proteins were characterized conclusively by matrix-assisted laser desorption/ ionization-time of flight-mass spectrometry (MAL-DI-TOF/TOF MS). The 14 proteins are immunogenic molecules of F. columnare, including chaperonins DnaK, GroEL and trigger factor, and translation elongation factor G, translation elongation factor Tu, 30S ribosomal subunit protein S1, dihydrolipoamide succinyltransferase, succinyl-CoA synthetase, SpoOJ regulator protein, alcohol dehydrogenase, fructose-bisphosphate aldolase, 3-hydroxybutyryl-CoA dehydrogenase and two conserved hypothetical proteins. These identified immunogenic proteins may provide candidate molecules for the development of vaccines against columnaris disease.

This paper concerns the dynamic stability of the steady 3-D wave structure of a planar normal shock front intersecting perpendicularly to a planar solid wall for unsteady potential flows. The stability problem can be formulated as a free boundary problem of a quasi-linear hyperbolic equation of second order in a dihedral-space domain between the shock front and the solid wall. The key difficulty is brought by the edge singularity of the space domain, the intersection curve between the shock front and the solid wall. Different from the 2-D case, for which the singular part of the boundary is only a point, it is a curve for the 3-D case in this paper. This difference brings new difficulties to the mathematical analysis of the stability problem. A modified partial hodograph transformation is introduced such that the extension technique developed for the 2-D case can be employed to establish the well-posed theory for the initial-boundary value problem of the linearized hyperbolic equation of second order in a dihedral-space domain. Moreover, the extension technique is improved in this paper such that loss of regularity in the a priori estimates on the shock front does not occur. Thus the classical nonlinear iteration scheme can be constructed to prove the existence of the solution to the stability problem, which shows the dynamic stability of the steady planar normal shock without applying the Nash-Moser iteration method.