Remarkably, infection of cells by WU95Hu−H3 was not increased upon transfection with ST3Gal4 even though WU95Hu−H3 and FU02Hu−H3 displayed similar 2-3Sia/2-6Sia KD ratios and infection of FU02Hu−H3 was increased by ST3Gal4 transfection of all four cell lines. Here, ST3GAL4 is linked to infection.