Paraskevopoulou, Sofia, Pirzer, Fabian, Goldmann, Nora, Schmid, Julian, Corman, Victor Max, Gottula, Lina Theresa, Schroeder, Simon, Rasche, Andrea, Muth, Doreen, Drexler, Jan Felix, Heni, Alexander Christoph, Eibner, Georg Joachim, Page, Rachel A., Jones, Terry C., Müller, Marcel A., Sommer, Simone, Glebe, Dieter, and Drosten, Christian. 2020. "Mammalian deltavirus without hepadnavirus coinfection in the neotropical rodent Proechimys semispinosus." Proceedings of the National Academy of Sciences of the United States of America, 117, (30) 17977–17983. https://doi.org/10.1073/pnas.2006750117.
Hepatitis delta virus (HDV) is a human hepatitis-causing RNA virus, unrelated to any other taxonomic group of RNA viruses. Its occurrence as a satellite virus of hepatitis B virus (HBV) is a singular case in animal virology for which no consensus evolutionary explanation exists. Here we present a mammalian deltavirus that does not occur in humans, identified in the neotropical rodent species Proechimys semispinosus . The rodent deltavirus is highly distinct, showing a common ancestor with a recently described deltavirus in snakes. Reverse genetics based on a tandem minus-strand complementary DNA genome copy under the control of a cytomegalovirus (CMV) promoter confirms autonomous genome replication in transfected cells, with initiation of replication from the upstream genome copy. In contrast to HDV, a large delta antigen is not expressed and the farnesylation motif critical for HBV interaction is absent from a genome region that might correspond to a hypothetical rodent large delta antigen. Correspondingly, there is no evidence for coinfection with an HBV-related hepadnavirus based on virus detection and serology in any deltavirus-positive animal. No other coinfecting viruses were detected by RNA sequencing studies of 120 wild-caught animals that could serve as a potential helper virus. The presence of virus in blood and pronounced detection in reproductively active males suggest horizontal transmission linked to competitive behavior. Our study establishes a nonhuman, mammalian deltavirus that occurs as a horizontally transmitted infection, is potentially cleared by immune response, is not focused in the liver, and possibly does not require helper virus coinfection.
