Thus, lymphocytes (CD4+ and CD8+ T cells and CD20+ B cells) and NK cells (CD56+) were almost completely resistant to HK-R2, whereas HK and HK-H17R infected these cells at a level of 20 to 40 % (MOI 3) with HK-H17R showing a higher infection rate than HK in CD4+ T cells and NK cells. Here, CD4 is linked to infection.