Current perspectives on the phylogeny of Filoviridae

Abstract

Sporadic fatal outbreaks of disease in humans and non-human primates caused by Ebola or Marburg viruses have driven research into the characterization of these viruses with the hopes of identifying host tropisms and potential reservoirs. Such an understanding of the relatedness of newly discovered filoviruses may help to predict risk factors for outbreaks of hemorrhagic disease in humans and/or non-human primates. Recent discoveries such as three distinct genotypes of Reston ebolavirus, unexpectedly discovered in domestic swine in the Philippines; as well as a new species, Bundibugyo ebolavirus; the recent discovery of Lloviu virus as a potential new genus, Cuevavirus, within Filoviridae; and germline integrations of filovirus-like sequences in some animal species bring new insights into the relatedness of filoviruses, their prevalence and potential for transmission to humans. These new findings reveal that filoviruses are more diverse and may have had a greater influence on the evolution of animals than previously thought. Herein we review these findings with regard to the implications for understanding the host range, prevalence and transmission of Filoviridae.

Fig. 1

Genome representations of Marburg viruses and Ebola viruses. Open reading frames and intergenic regions are indicated as shaded and unshaded boxes, respectively. Overlapping intergenic regions are shown as split boxes.

Fig. 2

Consensus phylogenetic tree of filovirus complete genomes. Phylogenetic analysis was conducted on 33 aligned filovirus full genome nucleotide sequences using the Maximum Composite Likelihood method (Tamura et al., 2004). Evolutionary history was inferred using the Neighbor-Joining method (Saitou and Nei, 1987) in MEGA 4 (Tamura et al., 2007) and using software default settings with the complete deletion option enabled. The tree shown is the consensus of a 1000 randomly assorted bootstrap replicates (Felsenstein, 1985).

Fig. 3

Consensus phylogenetic tree of endogenous and exogenous filovirus VP35 nucleotide sequences. VP35 sequences were analyzed using the Neighbor-Joining method (Saitou and Nei, 1987) in MEGA 4 (Tamura et al., 2007). The analysis was performed under the software default settings, except that evolutionary distances were computed using the Dayhoff matrix (Schwartz and Dayhoff, 1979) with the MEGA complete deletion option enabled. The rooted consensus tree was drawn based on 1000 randomly assorted bootstrap replicates (Felsenstein, 1985), with the Wallaby sequence integration being artificially designated as an outgroup based on its sequence containing multiple alignment gaps and stop codons. (∗) indicates sequence data derived from (Belyi et al., 2010).