TNF and infection: Not surprisingly, anti-TNFα therapy increases patient susceptibility to infection by various viruses (e.g., HIV and Epstein-Barr virus) by countering the protective antiviral effect of this cytokine.54,55 This factor has long been known to have antiviral activity mediated by killing infected cells directly or by increasing uninfected cell resistance to infection.56–59 These observations suggest that the presence of TNFα is not compatible with lentiviral transduction.