New Perspectives on Ebola Virus Evolution

• Published in: PloS one 2016-08, Vol.11 (8), p.e0160410
• Main Authors: Brown, Celeste J, Quates, Caleb J, Mirabzadeh, Christopher A, Miller, Craig R, Wichman, Holly A, Miura, Tanya A, Ytreberg, F Marty
• Format: Article
• Language: English
• Subjects: Adaptive structures; Africa, Western - epidemiology; Amino Acid Sequence; Amino acids; Analysis; Binding sites; Bioinformatics; Biology and Life Sciences; Chiroptera; Computer and Information Sciences; Disease Outbreaks; Ebola virus; Ebolavirus; Ebolavirus - isolation & purification; Ebolavirus - metabolism; Ebolavirus - physiology; Epidemics; Epidemiology; Evolution; Evolution, Molecular; Gene sequencing; Genetics; Genomes; Glycoproteins; Glycoproteins - classification; Glycoproteins - genetics; Glycoproteins - metabolism; Glycosylation; Hemorrhagic Fever, Ebola - diagnosis; Hemorrhagic Fever, Ebola - epidemiology; Hemorrhagic Fever, Ebola - virology; Humans; Immune response; Immune system; Immunoglobulins; Infections; Infectious diseases; Medicine and Health Sciences; Molecular biology; Mucin; Mutagenesis, Site-Directed; N-Terminus; Outbreaks; Phylogenetics; Phylogeny; Physical Sciences; Physics; Positive selection; Protein structure; Protein Structure, Tertiary; Proteins; Research and Analysis Methods; Risk factors; RNA polymerase; Rooting; Spike glycoprotein; Studies; Viral diseases; Viral Envelope Proteins - classification; Viral Envelope Proteins - genetics; Viral Envelope Proteins - metabolism; Virology; Viruses; Zoonoses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0160410

Since the recent devastating outbreak of Ebola virus disease in western Africa, there has been significant effort to understand the evolution of the deadly virus that caused the outbreak. There has been a considerable investment in sequencing Ebola virus (EBOV) isolates, and the results paint an important picture of how the virus has spread in western Africa. EBOV evolution cannot be understood outside the context of previous outbreaks, however. We have focused this study on the evolution of the EBOV glycoprotein gene (GP) because one of its products, the spike glycoprotein (GP1,2), is central to the host immune response and because it contains a large amount of the phylogenetic signal for this virus. We inferred the maximum likelihood phylogeny of 96 nonredundant GP gene sequences representing each of the outbreaks since 1976 up to the end of 2014. We tested for positive selection and considered the placement of adaptive amino acid substitutions along the phylogeny and within the protein structure of GP1,2. We conclude that: 1) the common practice of rooting the phylogeny of EBOV between the first known outbreak in 1976 and the next outbreak in 1995 provides a misleading view of EBOV evolution that ignores the fact that there is a non-human EBOV host between outbreaks; 2) the N-terminus of GP1 may be constrained from evolving in response to the host immune system by the highly expressed, secreted glycoprotein, which is encoded by the same region of the GP gene; 3) although the mucin-like domain of GP1 is essential for EBOV in vivo, it evolves rapidly without losing its twin functions: providing O-linked glycosylation sites and a flexible surface.