Ebolavirus evolves in human to minimize the detection by immune cells by accumulating adaptive mutations

Area of Science:

• Virology
• Evolutionary Biology
• Immunology

Background:

• The 2014 Zaire ebolavirus (EBOV) outbreak highlighted the urgent need for effective treatments and vaccines.
• Understanding host immune pressure and viral immune evasion mechanisms is critical for EBOV control.

Purpose of the Study:

• To identify adaptive selection pressures on amino acid sites of EBOV strains from the 2014 outbreak.
• To analyze the evolutionary dynamics of EBOV in response to host immunity.

Main Methods:

• Utilized multiple statistical methods including SLAC, FEL, REL, IFEL, FUBAR, and MEME to detect selection pressures.
• Employed computational RNA structure prediction to assess the impact of nucleotide mutations.

Main Results:

• Identified 11 and 14 amino acid sites under positive and negative selection, respectively, across key EBOV proteins.
• Found that 11 of the 25 selected sites are involved in T and B-cell epitopes.
• Observed purifying selection pressure, indicating viral adaptation to the human host and reduced immune recognition.

Conclusions:

• EBOV strains have evolved adaptive mutations to evade T and B-cell detection, enhancing survival fitness.
• Synonymous mutations in the NP gene may affect RNA secondary structure and genome replication.
• Findings provide insights into EBOV evolution and immune evasion, informing future vaccine and therapeutic strategies.