Fig. 4.

A single nucleotide substitution A140C, precludes RHA binding to PBS-segment, and diminishes infectivity of virions. (a) One-dimension ¹H spectra for PBS and PBS-A140C. While many of the major sharp signals remained unchanged, a few new small peaks were detected as denoted by asterisks (*), demonstrating local structural alternations in the PBS segment RNA. (b) The A140C mutation moderately reduces RHA^N300 binding (red) relative to 5′-L³⁴⁴ (black). (c) Infectivity of WT, ΔPBS, and A140C virions on TZM-bl cells was measured by Luciferase assays. Equivalent amounts of virions based on Gag ELISA were used to infect TZM-bl cells. The A140C mutation led to ∼ 60% reduction in infectivity as depicted in the graph (p≤0.001). ΔPBS and Mock serve as negative controls. Assays were performed in triplicate in three replicated experiments.