Seems to be required for maximal rate of protein biosynthesis. Enhances ribosome dissociation into subunits and stabilizes the binding of the initiator Met-tRNA(I) to 40 S ribosomal subunits. (Microbial infection) Interacts with human respiratory syncytial virus (HRSV) nucleoprotein; this interaction recruits EIF1AX to the viral replication complex to facilitate viral genomic RNA synthesis and virus production. Belongs to the eIF-1A family.