Viruses in unexplained encephalitis cases in American black bears (Ursus americanus)

Charles E. Alex, Elizabeth Fahsbender, Eda Altan, Robert Bildfell, Peregrine Wolff, Ling Jin, Wendy Black, Kenneth Jackson, Leslie Woods, Brandon Munk, Tiffany Tse, Eric Delwart, Patricia A. Pesavento

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Viral infections were investigated in American black bears (Ursus americanus) from Nevada and northern California with and without idiopathic encephalitis. Metagenomics analyses of tissue pools revealed novel viruses in the genera Circoviridae, Parvoviridae, Anelloviridae, Polyomaviridae, and Papillomaviridae. The circovirus and parvovirus were of particular interest due to their potential importance as pathogens. We characterized the genomes of these viruses and subsequently screened bears by PCR to determine their prevalence. The circovirus (Ursus americanus circovirus, UaCV) was detected at a high prevalence (10/16, 67%), and the chaphamaparvovirus (Ursus americanus parvovirus, UaPV) was found in a single bear. We showed that UaCV is present in liver, spleen/lymph node, and brain tissue of selected cases by in situ hybridization (ISH) and PCR. Infections were detected in cases of idiopathic encephalitis and in cases without inflammatory brain lesions. Infection status was not clearly correlated with disease, and the significance of these infections remains unclear. Given the known pathogenicity of a closely related mammalian circovirus, and the complex manifestations of circovirus-associated diseases, we suggest that UaCV warrants further study as a possible cause or contributor to disease in American black bears.

Original languageEnglish (US)
Article numbere0244056
JournalPloS one
Issue number12
StatePublished - Dec 2020

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General


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