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Characterization of a Novel Hepadnavirus in the White Sucker (Catostomus commersonii) from the Great Lakes Region of the United States.

ABSTRACT: The white sucker Catostomus commersonii is a freshwater teleost often utilized as a resident sentinel. Here, we sequenced the full genome of a hepatitis B-like virus that infects white suckers from the Great Lakes Region of the United States. Dideoxy sequencing confirmed that the white sucker hepatitis B virus (WSHBV) has a circular genome (3,542 bp) with the prototypical codon organization of hepadnaviruses. Electron microscopy demonstrated that complete virions of approximately 40 nm were present in the plasma of infected fish. Compared to avi- and orthohepadnaviruses, sequence conservation of the core, polymerase, and surface proteins was low and ranged from 16 to 27% at the amino acid level. An X protein homologue common to the orthohepadnaviruses was not present. The WSHBV genome included an atypical, presumptively noncoding region absent in previously described hepadnaviruses. Phylogenetic analyses confirmed WSHBV as distinct from previously documented hepadnaviruses. The level of divergence in protein sequences between WSHBV and other hepadnaviruses and the identification of an HBV-like sequence in an African cichlid provide evidence that a novel genus of the family Hepadnaviridae may need to be established that includes these hepatitis B-like viruses in fishes. Viral transcription was observed in 9.5% (16 of 169) of white suckers evaluated. The prevalence of hepatic tumors in these fish was 4.9%, and only 2.4% of fish were positive for both virus and hepatic tumors. These results are not sufficient to draw inferences regarding the association of WSHBV and carcinogenesis in white sucker.We report the first full-length genome of a hepadnavirus from fishes. Phylogenetic analysis of this genome indicates divergence from genomes of previously described hepadnaviruses from mammalian and avian hosts and supports the creation of a novel genus. The discovery of this novel virus may better our understanding of the evolutionary history of hepatitis B-like viruses of other hosts. In fishes, knowledge of this virus may provide insight regarding possible risk factors associated with hepatic neoplasia in the white sucker. This may also offer another model system for mechanistic research.

SUBMITTER: Hahn CM

PROVIDER: S-EPMC4645335 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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Characterization of a Novel Hepadnavirus in the White Sucker (Catostomus commersonii) from the Great Lakes Region of the United States.

Hahn Cassidy M CM Iwanowicz Luke R LR Cornman Robert S RS Conway Carla M CM Winton James R JR Blazer Vicki S VS

Journal of virology 20150916 23

<h4>Unlabelled</h4>The white sucker Catostomus commersonii is a freshwater teleost often utilized as a resident sentinel. Here, we sequenced the full genome of a hepatitis B-like virus that infects white suckers from the Great Lakes Region of the United States. Dideoxy sequencing confirmed that the white sucker hepatitis B virus (WSHBV) has a circular genome (3,542 bp) with the prototypical codon organization of hepadnaviruses. Electron microscopy demonstrated that complete virions of approximat ...[more]

PMID: 26378165

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Project description:Hepatitis B viruses belong to a family of circular, double-stranded DNA viruses that infect a range of organisms, with host responses that vary from mild infection to chronic infection and cancer. The white sucker hepatitis B virus (WSHBV) was first described in the white sucker (Catostomus commersonii), a freshwater teleost, and belongs to the genus Parahepadnavirus. At present, the host range of WSHBV and its impact on fish health are unknown, and neither genetic diversity nor association with fish health have been studied in any parahepadnavirus. Given the relevance of genomic diversity to disease outcome for the orthohepadnaviruses, we sought to characterize genomic variation in WSHBV and determine how it is structured among watersheds. We identified WSHBV-positive white sucker inhabiting tributaries of Lake Michigan, Lake Superior, Lake Erie (USA), and Lake Athabasca (Canada). Copy number in plasma and in liver tissue was estimated via qPCR. Templates from 27 virus-positive fish were amplified and sequenced using a primer-specific, circular long-range amplification method coupled with amplicon sequencing on the Illumina MiSeq. Phylogenetic analysis of the WSHBV genome identified phylogeographical clustering reminiscent of that observed with human hepatitis B virus genotypes. Notably, most non-synonymous substitutions were found to cluster in the pre-S/spacer overlap region, which is relevant for both viral entry and replication. The observed predominance of p1/s3 mutations in this region is indicative of adaptive change in the polymerase open reading frame (ORF), while, at the same time, the surface ORF is under purifying selection. Although the levels of variation we observed do not meet the criteria used to define sub/genotypes of human and avian hepadnaviruses, we identified geographically associated genome variation in the pre-S and spacer domain sufficient to define five WSHBV haplotypes. This study of WSHBV genetic diversity should facilitate the development of molecular markers for future identification of genotypes and provide evidence in future investigations of possible differential disease outcomes.

Project description:White-nose syndrome is a fungal disease that is threatening bat populations across North America. The disease primarily affects cave-hibernating bats by depleting fat reserves during hibernation and causing a range of other physiological consequences when immune responses are suppressed. Since it was first detected in 2006, the disease has killed millions of bats and is responsible for extensive local extinctions. To better understand the effects of white-nose syndrome on various bat species, we analyzed summer acoustic survey data collected from 2016 to 2020 at nine US National Parks within the Great Lakes region. We examined the effect that white-nose syndrome, time of the year relative to pup volancy, habitat type, and regional variation (i.e., park) have on the acoustic abundance (i.e., mean call abundance) of six bat species. As expected, little brown bat (Myotis lucifugus) and northern long-eared bat (Myotis septentrionalis), both hibernating species, experienced a significant decline in acoustic abundance following white-nose syndrome detection. We observed a significant increase in acoustic abundance as white-nose syndrome progressed for hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans), both migratory species that are not impacted by the disease. Contrary to our predictions, we observed an increase in big brown bat (Eptesicus fuscus; hibernating) acoustic abundance and a decrease in eastern red bat (Lasiurus borealis; migratory) acoustic abundance following the detection of white-nose syndrome. We did not observe any significant changes after the onset of white-nose syndrome in the seasonal patterns of acoustic activity related to pup volancy, suggesting that production or recruitment of young may not be affected by the disease. Our results suggest that white-nose syndrome is affecting the acoustic abundance of certain species; however, these changes may not be a result of reduced reproductive success caused by the disease. In addition, species population dynamics may be indirectly affected by white-nose syndrome as a result of reduced competition or a foraging niche release. We also found that for parks located at higher latitudes, little brown bat and northern long-eared bat were more likely to experience greater declines in acoustic abundance as a result of white-nose syndrome. Our work provides insight into species-specific responses to white-nose syndrome at a regional scale and examines factors that may facilitate resistance or resiliency to the disease.

Project description:Colored dissolved organic matter (CDOM), a major component of the dissolved organic carbon (DOC) pool in many lakes, is an important controlling factor in lake ecosystem functioning. Absorption coefficients at 440 nm (a440, m-1), a common measure of CDOM, exhibited strong associations with dissolved iron (Fediss) and DOC in 280 lakes of the Upper Great Lakes States (UGLS: Minnesota, Wisconsin, and Michigan), as has been found in Scandinavia and elsewhere. Linear regressions between the three variables on UGLS lake data typically yielded R2 values of 0.6-0.9, suggesting that some underlying common processes influence organic matter and Fediss. Statistical and experimental evidence, however, supports only a minor role for iron contributions to a440 in UGLS lakes. Although both DOC and Fediss were significant variables in linear and log-log regressions on a440, DOC was the stronger predictor; adding Fediss to the linear a440-DOC model improved the R2 only from 0.90 to 0.93. Furthermore, experimental additions of FeIII to colored lake waters had only small effects on a440 (average increase of 0.242 m-1 per 100 μg/L of added FeIII). For 136 visibly stained waters (with a440 > 3.0 m-1), where allochthonous DOM predominates, DOM accounted for 92.3 ± 5.0% of the measured a440 values, and Fediss accounted for the remainder. In 75% of the lakes, Fediss accounted for < 10% of a440, but contributions of 15-30% were observed for 7 river-influenced lakes. Contributions of Fediss in UGLS lakes to specific UV absorbance at 254 nm (SUVA254) generally were also low. Although Fediss accounted for 5-10% of measured SUVA254 in a few samples, on average, 98.1% of the SUVA254 signal was attributable to DOM and only 1.9% to Fediss. DOC predictions from measured a440 were nearly identical to those from a440 corrected to remove Fediss contributions. Overall, variations in Fediss in most UGLS lakes have very small effects on CDOM optical properties, such as a440 and SUVA254, and negligible effects on the accuracy of DOC estimated from a440, data for which can be obtained at broad regional scales by remote sensing methods.

Dataset Information

Characterization of a Novel Hepadnavirus in the White Sucker (Catostomus commersonii) from the Great Lakes Region of the United States.

Publications

Characterization of a Novel Hepadnavirus in the White Sucker (Catostomus commersonii) from the Great Lakes Region of the United States.

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