A study by Nowroozalizadeh et al. showed an inverse correlation between plasma LPS levels and expression of proinflammatory cytokines IL-12 and IFN-γ following TLR stimulation in HIV-2-infected, HAART-naïve individuals, whereas in HIV-2-infected individuals with AIDS, there was a positive correlation between LPS levels, CD4+ T-cell lymphopenia, and HIV RNA load similar to HIV-1 infection (63). Here, CD4 is linked to HIV-1 infection.