Identification of novel avian and mammalian deltaviruses provides new insights into deltavirus evolution

Abstract

Hepatitis delta virus (HDV) is a satellite virus that requires hepadnavirus envelope proteins for its transmission. Although recent studies identified HDV-related deltaviruses in certain animals, the evolution of deltaviruses, such as the origin of HDV and the mechanism of its coevolution with its helper viruses, is unknown, mainly because of the phylogenetic gaps among deltaviruses. Here we identified novel deltaviruses of passerine birds, woodchucks, and white-tailed deer by extensive database searches and molecular surveillance. Phylogenetic and molecular epidemiological analyses suggest that HDV originated from mammalian deltaviruses and the past interspecies transmission of mammalian and passerine deltaviruses. Further, metaviromic and experimental analyses suggest that the satellite-helper relationship between HDV and hepadnavirus was established after the divergence of the HDV lineage from non-HDV mammalian deltaviruses. Our findings enhance our understanding of deltavirus evolution, diversity, and transmission, indicating the importance of further surveillance for deltaviruses.

HDV-Like Viruses

“…Similarly, RDeV, OvirDeV, and tgDeV infections do not seem to be limited to the liver, as the virus’s sequence reads have been obtained from at least two different tissues. On occasion, data were consistent with a broad range or even systemic infection [ 23 , 25 , 27 ].…”

“…A central component of these hypotheses is that HDV had been found, until recently, only in humans. Yet, several viruses closely related to HDV have now been detected in non-human species in the absence of any hepadnavirus [ 22 , 23 , 24 , 25 , 26 , 27 ]. Further studies are warranted to ascertain whether these agents represent satellite viruses dependent on a helper virus for their propagation, or alternatively, they are examples of a novel family of autonomous viroid-like agents in animals, whose transmission would occur by conventional receptor-mediated means.…”

“…Mammal deltaviruses have been identified in a neotropical rodent species Proechimys semispinosus (RDeV; [ 27 ]); in common vampire bats Desmodus rotundus (DrDeV-A and DrDeV-B); and in a liver transcriptome from a lesser dog-like bat Peropteryx macrotis (PmacDeV) [ 26 ]. Additional mammal deltavirus genomes were recovered from transcriptomes derived from white-tailed deer ( Odocoileus virginianus ; OvirDeV) and from captive-born Eastern woodchucks ( Marmota monax ; mmDeV) [ 25 , 26 ]. Three more deltavirus-like sequences have been also identified in birds, Taeniopygia guttata deltavirus (tgDeV), Serinus canaria -associated deltavirus (scDeV), and Erythrura gouldiae deltavirus (egDeV) [ 25 ].…”

“…Additional mammal deltavirus genomes were recovered from transcriptomes derived from white-tailed deer ( Odocoileus virginianus ; OvirDeV) and from captive-born Eastern woodchucks ( Marmota monax ; mmDeV) [ 25 , 26 ]. Three more deltavirus-like sequences have been also identified in birds, Taeniopygia guttata deltavirus (tgDeV), Serinus canaria -associated deltavirus (scDeV), and Erythrura gouldiae deltavirus (egDeV) [ 25 ].…”

In Vivo Models of HDV Infection: Is Humanizing NTCP Enough?

“…These HDV-like viruses were detected in different organs (brain, liver, kidney, gut, lung) and persisted completely in the absence of a co-infection with HBV-related hepadnaviruses. A recent study performing a transcriptome data analysis also identified novel HDV-related sequences in birds and mammals including the zebra finch (taeniopygia guttata), common canary (serinus canaria), Gouldian finch (erythrura gouldiae), Eastern woodchuck (marmota monax), and white-tailed deer (odocoileus virginianus) [63]. Moreover, snake HDV was able to replicate in different snake, monkey, and human cell lines after their transfection with a plasmid expressing snake HDV genomes.…”