CD4 and infection: Since infection with VSV-G-pseudotyped virions was not as sensitive to TLR2 stimulation as infection with BaL- or BR-pseudotyped viruses, it seems plausible that the effects on HIV-1 infectivity of MDMs through TLR2 stimulation may be more related to the modulation of the expression levels of CD4 and CCR5 than those induced through other TLRs.