Early mesozoic coexistence of amniotes and hepadnaviridae.

PLoS Genet 2014 Dec 11;10(12):e1004559. Epub 2014 Dec 11.

Department of Evolutionary Biology (EBC), Uppsala University, Uppsala, Sweden.

Hepadnaviridae are double-stranded DNA viruses that infect some species of birds and mammals. This includes humans, where hepatitis B viruses (HBVs) are prevalent pathogens in considerable parts of the global population. Recently, endogenized sequences of HBVs (eHBVs) have been discovered in bird genomes where they constitute direct evidence for the coexistence of these viruses and their hosts from the late Mesozoic until present. Nevertheless, virtually nothing is known about the ancient host range of this virus family in other animals. Here we report the first eHBVs from crocodilian, snake, and turtle genomes, including a turtle eHBV that endogenized >207 million years ago. This genomic "fossil" is >125 million years older than the oldest avian eHBV and provides the first direct evidence that Hepadnaviridae already existed during the Early Mesozoic. This implies that the Mesozoic fossil record of HBV infection spans three of the five major groups of land vertebrates, namely birds, crocodilians, and turtles. We show that the deep phylogenetic relationships of HBVs are largely congruent with the deep phylogeny of their amniote hosts, which suggests an ancient amniote-HBV coexistence and codivergence, at least since the Early Mesozoic. Notably, the organization of overlapping genes as well as the structure of elements involved in viral replication has remained highly conserved among HBVs along that time span, except for the presence of the X gene. We provide multiple lines of evidence that the tumor-promoting X protein of mammalian HBVs lacks a homolog in all other hepadnaviruses and propose a novel scenario for the emergence of X via segmental duplication and overprinting of pre-existing reading frames in the ancestor of mammalian HBVs. Our study reveals an unforeseen host range of prehistoric HBVs and provides novel insights into the genome evolution of hepadnaviruses throughout their long-lasting association with amniote hosts.

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pgen.1004559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4263362PMC
December 2014
26 Reads

Publication Analysis

Top Keywords

early mesozoic
12
direct evidence
8
host range
8
amniote hosts
8
mammalian hbvs
8
hbvs
7
ago genomic
4
codivergence early
4
overprinting pre-existing
4
years ago
4
time span
4
>207 years
4
mesozoic notably
4
genomic "fossil"
4
duplication overprinting
4
oldest avian
4
segmental duplication
4
older oldest
4
years older
4
coexistence codivergence
4

References

(Supplied by CrossRef)
Our viral inheritance
RA Weiss et al.
Science 2013
Endogenous viral elements in animal genomes
A Katzourakis et al.
PLoS Genetics 2010
Endless forms most viral
WE Johnson et al.
PLoS Genetics 2010
The evolution of endogenous viral elements
EC Holmes et al.
Cell Host & Microbe 2011
Genome sequencing and population genomics in non-model organisms
H Ellegren et al.
Trends in Ecology & Evolution 2014
Paleovirology – ghosts and gifts of viruses past
MR Patel et al.
Current Opinion in Virology 2011
Macroevolution of complex retroviruses
A Katzourakis et al.
Science 2009

Similar Publications