Infection of a chimeric simian and human immunodeficiency virus with CCR5-specific HIV-1 envelope to Rhesus macaques

Innate immunity in experimental SIV infection and vaccination

Innate immunity represents the first line of defence to pathogens besides the physical barrier and seems to play a role in protection against HIV/SIV infection and disease progression. High production of beta-chemokines and CD8+ T cell anti-viral factors in naive as well as in vaccinated macaques has been associated with complete or partial protection against SIV infection indicating that genetic or environmental factors may influence their production. This innate immunity may help in generating HIV/SIV-specific responses upon the first exposure to HIV/SIV. SIV subunit vaccines given by the targeted iliac lymph node route have been shown to induce an increased production of CD8+ T cell suppressor factors and beta-chemokines. Only a few vaccine studies have focused on enhancing the innate immune response against HIV/SIV. The use of unmethylated CpG motifs, HSP and GM-CSF as adjuvants in SIV vaccines has been shown to induce production of HIV/SIV-inhibiting cytokines and beta-chemokines, which seem to be important in modulating and steering the adaptive immune responses. HSP has also been shown to induce gammadelta+ T cells, which contribute to the innate immunity. More knowledge about the interplay between the innate and adaptive immune responses is important to develop new HIV/SIV vaccine strategies.

Use of a small molecule CCR5 inhibitor in macaques to treat simian immunodeficiency virus infection or prevent simian-human immunodeficiency virus infection

Human immunodeficiency virus type 1 (HIV-1) fuses with cells after sequential interactions between its envelope glycoproteins, CD4 and a coreceptor, usually CC chemokine receptor 5 (CCR5) or CXC receptor 4 (CXCR4). CMPD 167 is a CCR5-specific small molecule with potent antiviral activity in vitro. We show that CMPD 167 caused a rapid and substantial (4–200-fold) decrease in plasma viremia in six rhesus macaques chronically infected with simian immunodeficiency virus (SIV) strains SIVmac251 or SIVB670, but not in an animal infected with the X4 simian–human immunodeficiency virus (SHIV), SHIV-89.6P. In three of the SIV-infected animals, viremia reduction was sustained. In one, there was a rapid, but partial, rebound and in another, there was a rapid and complete rebound. There was a substantial delay (>21 d) between the end of therapy and the onset of full viremia rebound in two animals. We also evaluated whether vaginal administration of gel-formulated CMPD 167 could prevent vaginal transmission of the R5 virus, SHIV-162P4. Complete protection occurred in only 2 of 11 animals, but early viral replication was significantly less in the 11 CMPD 167-recipients than in 9 controls receiving carrier gel. These findings support the development of small molecule CCR5 inhibitors as antiviral therapies, and possibly as components of a topical microbicide to prevent HIV-1 sexual transmission.