Topical application of entry inhibitors as "virustats" to prevent sexual transmission of HIV infection

With the continuing march of the AIDS epidemic and little hope for an effective vaccine in the near future, work to develop a topical strategy to prevent HIV infection is increasingly important. This stated, the track record of large scale "microbicide" trials has been disappointing with nonspecific inhibitors either failing to protect women from infection or even increasing HIV acquisition. Newer strategies that target directly the elements needed for viral entry into cells have shown promise in non-human primate models of HIV transmission and as these agents have not yet been broadly introduced in regions of highest HIV prevalence, they are particularly attractive for prophylaxis. We review here the agents that can block HIV cellular entry and that show promise as topical strategies or "virustats" to prevent mucosal transmission of HIV infectio

Dynamics of Immune Reconstitution and Activation Markers in HIV+ Treatment-Naïve Patients Treated with Raltegravir, Tenofovir Disoproxil Fumarate and Emtricitabine

Background: The dynamics of CD4+ T cell reconstitution and changes in immune activation and inflammation in HIV-1 disease following initiation of antiretroviral therapy (ART) are incompletely defined and their underlying mechanisms poorly understood. Methods: Thirty-nine treatment-naïve patients were treated with raltegravir, tenofovir DF and emtricitabine. Immunologic and inflammatory indices were examined in persons with sustained virologic control during 48 weeks of therapy. Results: Initiation of ART increased CD4+ T cell numbers and decreased activation and cell cycle entry among CD4+ and CD8+ T cell subsets, and attenuated markers of coagulation (D-dimer levels) and inflammation (IL-6 and TNFr1). These indices decayed at different rates and almost all remained elevated above levels measured in HIV-seronegatives through 48 weeks of viral control. Greater first and second phase CD4+ T cell restoration was related to lower T cell activation and cell cycling at baseline, to their decay with treatment, and to baseline levels of selected inflammatory indices, but less so to their changes on therapy. Conclusions: ART initiation results in dynamic changes in viral replication, T cell restoration, and indices of immune activation, inflammation, and coagulation. These findings suggest that determinants of T cell activation/cycling and inflammation/coagulation may have distinguishable impact on immune homeostasis. Trial Registration Clinicaltrials.gov NCT0066097

Interferon-α is the primary plasma type-I IFN in HIV-1 infection and correlates with immune activation and disease markers.

Type-I interferon (IFN-I) has been increasingly implicated in HIV-1 pathogenesis. Various studies have shown elevated IFN-I and an IFN-I-induced gene and protein expression signature in HIV-1 infection, yet the elevated IFN-I species has not been conclusively identified, its source remains obscure and its role in driving HIV-1 pathogenesis is controversial. We assessed IFN-I species in plasma by ELISAs and bioassay, and we investigated potential sources of IFN-I in blood and lymph node tissue by qRT-PCR. Furthermore, we measured the effect of therapeutic administration of IFNα in HCV-infected subjects to model the effect of IFNα on chronic immune activation. IFN-I bioactivity was significantly increased in plasma of untreated HIV-1-infected subjects relative to uninfected subjects (p = 0.012), and IFNα was the predominant IFN-I subtype correlating with IFN-I bioactivity (r = 0.658, p<0.001). IFNα was not detectable in plasma of subjects receiving anti-retroviral therapy. Elevated expression of IFNα mRNA was limited to lymph node tissue cells, suggesting that peripheral blood leukocytes are not a major source of IFNα in untreated chronic HIV-1 infection. Plasma IFN-I levels correlated inversely with CD4 T cell count (p = 0.003) and positively with levels of plasma HIV-1 RNA and CD38 expression on CD8 T cells (p = 0.009). In hepatitis C virus-infected subjects, treatment with IFN-I and ribavirin increased expression of CD38 on CD8 T cells (p = 0.003). These studies identify IFNα derived from lymph nodes, rather than blood leukocytes, as a possible source of the IFN-I signature that contributes to immune activation in HIV-1 infection

Circulating human CD4 and CD8 T cells do not have large intracellular pools of CCR5

CC Chemokine Receptor 5 (CCR5) is an important mediator of chemotaxis and the primary coreceptor for HIV-1. A recent report by other researchers suggested that primary T cells harbor pools of intracellular CCR5. With the use of a series of complementary techniques to measure CCR5 expression (antibody labeling, Western blot, quantitative reverse transcription polymerase chain reaction), we established that intracellular pools of CCR5 do not exist and that the results obtained by the other researchers were false-positives that arose because of the generation of irrelevant binding sites for anti-CCR5 antibodies during fixation and permeabilization of cells

IFNα and its signature are increased in plasma of HIV-1-infected subjects not receiving ART.

<p>Plasma IFN-I bioactivity measured by the iLite™ bioassay was increased in plasma of HIV-1-infected subjects in comparison to uninfected subjects (median 1.04 IFNα2 equivalent units for HIV-1-infected subjects, median 0.89 IFNα2 equivalent units for uninfected subjects, p = 0.012) (A). IFNα was increased in plasma of HIV-1-infected subjects in comparison to uninfected subjects (median 4.27 pg/ml for HIV-1-infected subjects, median 3.13 pg/ml for uninfected subjects, p<0.001) (B). IFNβ was not increased in plasma of HIV-1-infected subjects compared to uninfected subjects (median 2.34 pg/ml for HIV-1-infected subjects, median 2.34 pg/ml for uninfected subjects, p = 0.560) (B). IFNω was not increased in plasma of HIV-1-infected subjects compared to uninfected subjects (median 4.69 pg/ml for HIV-1-infected subjects, median 4.69 pg/ml for uninfected subjects, p = 0.837) (B). Plasma IFNα levels were strongly associated with plasma IFN-I bioactivity in HIV-1-infected subjects (r = 0.711, p<0.001) (C). Plasma IP-10 was increased in plasma of HIV-1-infected subjects in comparison to uninfected subjects (median 538.2 pg/ml for HIV-1-infected subjects, median 132.6 pg/ml for uninfected subjects, p = 0.002) (D). Slight variations in sample sizes for different assays occur as results for some subjects were not available.</p

Therapeutic administration of IFNα induces increased expression of the activation marker CD38 on memory CD8 T cells in HCV-infected subjects.

<p>A longitudinal study was conducted to assess CD38 expression on memory (CD45RO+) CD8 T cells. Seven HCV-infected (HIV-1-uninfected) subjects were studied immediately prior to initiation of therapy with s.c. pegylated IFNα and oral ribavirin, and after 4 and 12 weeks of therapy. CD38-specific MFI (MFI for CD38 minus MFI for IgG1 isotype control) increased on memory CD8 T cells in all seven treated subjects at 4 weeks of therapy (p = 0.018). A further increase in CD38 was observed in five of seven subjects by week 12 of therapy (p = 0.018). The difference in CD38 expression between week 0 (prior to therapy) and week 12 was highly significant (p = 0.018).</p

IFNα mRNA expression is elevated in lymph nodes, but not peripheral blood leukocytes, of HIV-1-infected subjects.

<p>There was no significant difference in expression of IFNα mRNA in whole blood leukocytes of HIV-1-infected subjects without ART (median relative expression of 0.10) and uninfected subjects (median relative expression of 0.88) (p = 0.981) (A). Similarly, there was no significant difference in IFNβ mRNA expression in whole blood leukocytes (median relative expression of 0.003 for HIV-1-infected subjects, median relative expression of 0.001 for uninfected subjects; p = 0.298) (A). An IFN-I signature was evident in peripheral blood leukocytes, as expression of the ISG MxA was significantly increased in HIV-1-infected subjects without ART compared to uninfected subjects (median relative expression of 0.85 for HIV-1-infected subjects, median relative expression of 0.26 for uninfected subjects; p = 0.016) (A). In contrast, expression of IFNα mRNA in lymph node tissue was significantly elevated in HIV-1-infected subjects without ART (median relative expression of 0.93) relative to uninfected subjects (median relative expression of 0.12) (p = 0.037) (B). There was no statistically significant difference in IFNβ mRNA expression between the two donor groups (median relative expression of 0.20 for HIV-1-infected subjects, median relative expression of 0.06 for uninfected subjects; p = 0.728) (B). Expression of the ISG MxA was significantly increased in lymph node tissue from HIV-1-infected subjects compared to uninfected subjects (median relative expression of 1.05 for HIV-1-infected subjects vs. 0.45 for uninfected subjects; p = 0.037) (B).</p

Plasma IFNα and IFN-I bioactivity are associated with plasma HIV-1 RNA levels, CD4 T cell count and immune activation in untreated subjects with chronic HIV-1-infection.

<p>Plasma HIV-1 RNA levels in HIV-1-infected subjects without ART correlated positively with plasma IFN-I bioactivity (r = 0.329, p = 0.017) (A), as well as with plasma IFNα (r = 0.356, p = 0.008) (B). Absolute CD4 T cell count in these subjects correlated inversely with plasma IFN-I bioactivity (r = -0.426, p = 0.002) (C) and plasma IFNα (r = -0.407, p = 0.002) (D). Expression of CD38 by memory (CD45RO+) CD8 T cells in these subjects correlated positively with plasma IFN-I bioactivity (r = 0.374, p = 0.021) (E) and with plasma IFNα (r = 0.387, p = 0.01) (F).</p

Plasma IFNα and IP-10 levels are comparable between HIV-1 infected subjects on ART and uninfected subjects.

<p>IFNα and IP-10 levels were determined in the plasma of 25 individuals with chronic HIV-1 infection who received ART and responded with HIV-1 RNA below assay detection limits (<50 copies/ml) for two years or more. IFNα was detected in plasma from only one such donor, and then at trace levels (A). The difference in plasma IFNα level between HIV-1 infected subjects without ART and HIV-1-infected subjects with ART was highly significant (p<0.001). Plasma IP-10 levels in ART-treated HIV-1-infected donors were comparable to those in uninfected donors (p = 0.460) and were significantly lower in comparison to untreated HIV-1-infected donors (p<0.001) (B).</p