Search

Trionyx sinensis hemorrhagic syndrome virus (TSHSV) is a newly discovered lethal arterivirus that causes serious disease in Trionyx sinensis in China. In this study, the complete genome sequence of TSHSV was determined by RACE cloning, and the functions of the predicted proteins were predicted. The complete genome of TSHSV was found to be 17,875 bp in length, and a 3'-end poly(A) tail was detected. Eight TSHSV hypothetical proteins (TSHSV-HPs) were predicted by gene model identification. TSHSV-HP2, 3 and 4 were associated with replicase activity, since papain-like protease (PLPs), serine-type endopeptidase, P-loop-containing nucleoside triphosphate hydrolase, and EndoU-like endoribonuclease motifs were detected. Phylogenetic analysis showed that TSHSV clusters with an arterivirus from a Chinese broad-headed pond turtle.

Ranaviruses are nucleoplasmic large DNA viruses that can cause major economic losses in the aquaculture industry and pose a severe threat to global ecological diversity. The available literature demonstrates that classifiable members of the genus Ranavirus enter cells via multiple and complicated routes. Here, we demonstrated the underlying cellular entry mechanism of soft-shelled turtle iridovirus (STIV) using green fluorescence tagged recombinant virus. Treatment with chlorpromazine, sucrose, ethyl-isopropyl amiloride, chloroquine or bafilomycin A1 all significantly decreased STIV infection, suggesting that STIV uses clathrin-mediated endocytosis and macropinocytosis to enter cells via a pH-dependent pathway. Depletion of cellular cholesterol with methyl-β-cyclodextrin significantly inhibited STIV entry, but neither filipin III nor nystatin did, suggesting that STIV entry was cholesterol dependent but caveola independent. Treatment with dynasore, genistein, ML-7 or cytochalasin D all significantly inhibited STIV infection, indicating that Rac GTPase and myosin II activity were required for the macropinocytosis-like pathway as well as actin polymerization. Our findings suggest that the molecular events involved in STIV entry are not identical to those of other ranavirus isolates. Our results also extend our understanding of the molecular mechanism of iridovirus entry and pathogenesis.

Marine turtle fibropapillomatosis is an emerging disease that affects marine turtles worldwide. This report describes the histopathological features and involvement of chelonid fibropapilloma-associated herpesvirus in marine turtle fibropapillomatosis detected in the green turtle Chelonia mydas at Príncipe Island, Gulf of Guinea. The histopathological findings confirmed the presence of fibropapillomas with both verrucous and fibromatous subtypes. Quantitative real-time PCR was used for detection of chelonid fibropapilloma-associated herpesvirus in tissue samples (n = 18) collected from afflicted (n = 10) and apparently healthy turtles (n = 2), revealing 94.4% positive samples, confirming the presence of viral sequences not only in fibropapillomatosis lesions but also in the skin of apparently healthy animals.

Through 4 consecutive genomic walks employing a recently modified inverse polymerase chain reaction technique, a 4,054-bp DNA fragment of a newfound green turtle herpesvirus (GTHV) was obtained from tumor tissues of a green turtle with fibropapillomas. This newly identified viral DNA fragment contains two non-overlapping open reading frames (ORF) oriented in the 3' to 5' direction. The first ORF is 59% G+C rich and contains the full-length genomic sequence of the DNA binding protein (DBP) gene (3,585 bp) encoding a protein of 1,195 amino acid residues in length. The second ORF encodes a partial peptide of the UL28 gene. Phylogenetic analysis of the GTHV DBP gene confirmed and substantiated that this novel Chelonian herpesvirus is closely related to the subfamily Alphaherpesvirinae. Examination of the translated amino acid sequence further supports this categorization since GTHV DBP comprises a highly conserved zinc finger motif (CXLCX4RX2C) and a putative DNA binding domain, and exhibits high sequence homology to other alphaherpesviruses. Cloning and sequencing the genome of this putative herpesvirus will facilitate current understanding of its role in causing GTFP and the development of molecular- and immuno-based methods for the diagnosis and prevention of this devastating disease of green turtles.

An alpha-herpesvirus has recently been associated with green turtle fibropapilloma (FP). To further understand the etiological role of this newfound green turtle herpesvirus (GTHV) in the pathogenesis of FP, expression of GTHV polymerase ( pol) gene was determined in tumors and normal-appearing nontumor tissues and organs from five green turtles suffering multiple fibropapillomas, using reverse transcription-polymerase chain reaction (RT-PCR). Amplification of RNA prepared from tumor tissues evidenced the substantial expression of GTHV DNA pol gene in all specimens tested (15/15). However, GTHV pol gene expression in normal-appearing tissues and organs of affected animals was limited (4/45), and GTHV mRNA was detected only in periorbital tissue (1/2), gall bladder (2/5) and lung (1/5) by nested RT-PCR. By contrast, RT-PCR evaluation of RNA isolated from non-tumored turtles revealed undetectable expression of this herpesvirus gene. cDNA sequence analysis revealed that GTHV gene sequences were identical in different tumors. Our data represent the first evidence of the replication of this putative turtle herpesvirus in affected green turtles and fibropapilloma tissues are always active sites of GTHV mRNA synthesis. These findings extend and substantiate the pathogenic association of GTHV with FP.

A 1,632-bp fragment, flanking the original 483-bp region of the DNA polymerase gene of a novel herpesvirus found in tissues of green turtles (Chelonia mydas) with fibropapilloma, was amplified from the circularized EcoRI-cut DNA extracted from tumor tissues by inverse PCR. The resultant 2,019-bp partial sequence of the DNA polymerase gene of the newfound herpesvirus, including the original 483-bp region, showed a high degree of homology at both the nucleotide and amino acid levels with that of other human and animal herpesviruses. Phylogenetic analysis confirmed that this novel herpesvirus belonged to the Alphaherpesvirinae subfamily.

A virus was isolated from tissues of 2 diseased Hermann's tortoises (Testudo hermanni) and preliminarily characterized as an iridovirus. This conclusion was based on the presence of inclusion bodies in the cytoplasm of infected cells, sensitivity to chloroform, inhibition of virus replication by 5-iodo-2'-desoxyuridine and the size and icosahedral morphology of viral particles. The virus was able to replicate in several reptilian, avian and mammalian cell lines at 28 degrees C, but not at 37 degrees C. Restriction enzyme analysis showed resistance of the ral DNA to digestion with HpaII due to methylation of the internal cytosine at CCGG sequences. Part of the genomic region encoding the major capsid protein was amplified by PCR and subjected to sequence analysis. Comparative analysis of the obtained nucleotide sequence revealed that the isolate is closely related to frog virus 3, the type species of the genus Ranavirus.