<p>A panel of mutant and wild-type HN and F combinations were co-transfected into 293 T cells with the HIV-Luc vector. Pseudoviruses in the culture medium were harvested 48 h later and used to infect 293 T cells in 96-well plates. The luciferase activity of the infected cells was detected 48 h post infection and normalized with the titer of p24 in the pseudoviruses. All results are shown as means ± SD from four independent experiments. “**” indicated <i>P</i><0.01.</p
