TNF and HIV-1 infection: Experiments using tissue explants have shown that gram-positive bacteria such as Staphylococcus aureus, Group B Streptococcus and genital pathogens such as Candida albicans and Neisseria gonorrhea increase Langerhans' cells susceptibility to HIV-1 infection via TLR2 agonists and TNF-α production [17], [18].