CD40LG and infection: As a means of excluding the possibility that the simultaneous presence in patient serum of anti-WNV IgM or IgG produced during the acute phase of infection (WNV-NTAbs), itself conferred protection against WNV in vitro, we confirmed that the pretreatment of Vero E6 cells with all the 19 serum samples at a dilution of 1:100 or 1:10 did not confer protection against WNV infection in vitro (data not shown).