HIV-1 immune activation induces Siglec-1 expression and enhances viral trans-infection in blood and tissue myeloid cells.

BACKGROUND: Myeloid cells are key players in the recognition and response of the host against invading viruses. Paradoxically, upon HIV-1 infection, myeloid cells might also promote viral pathogenesis through trans-infection, a mechanism that promotes HIV-1 transmission to target cells via viral capture and storage. The receptor Siglec-1 (CD169) potently enhances HIV-1 trans-infection and is regulated by immune activating signals present throughout the course of HIV-1 infection, such as interferon α (IFNα). RESULTS: Here we show that IFNα-activated dendritic cells, monocytes and macrophages have an enhanced ability to capture and trans-infect HIV-1 via Siglec-1 recognition of viral membrane gangliosides. Monocytes from untreated HIV-1-infected individuals trans-infect HIV-1 via Siglec-1, but this capacity diminishes after effective antiretroviral treatment. Furthermore, Siglec-1 is expressed on myeloid cells residing in lymphoid tissues, where it can mediate viral trans-infection. CONCLUSIONS: Siglec-1 on myeloid cells could fuel novel CD4(+) T-cell infections and contribute to HIV-1 dissemination in vivo.

Comparison of Immunogenicity in Rhesus Macaques of Transmitted-Founder, HIV-1 Group M Consensus, and Trivalent Mosaic Envelope Vaccines Formulated as a DNA Prime, NYVAC, and Envelope Protein Boost.

An effective human immunodeficiency virus type 1 (HIV-1) vaccine must induce protective antibody responses, as well as CD4(+) and CD8(+) T cell responses, that can be effective despite extraordinary diversity of HIV-1. The consensus and mosaic immunogens are complete but artificial proteins, computationally designed to elicit immune responses with improved cross-reactive breadth, to attempt to overcome the challenge of global HIV diversity. In this study, we have compared the immunogenicity of a transmitted-founder (T/F) B clade Env (B.1059), a global group M consensus Env (Con-S), and a global trivalent mosaic Env protein in rhesus macaques. These antigens were delivered using a DNA prime-recombinant NYVAC (rNYVAC) vector and Env protein boost vaccination strategy. While Con-S Env was a single sequence, mosaic immunogens were a set of three Envs optimized to include the most common forms of potential T cell epitopes. Both Con-S and mosaic sequences retained common amino acids encompassed by both antibody and T cell epitopes and were central to globally circulating strains. Mosaics and Con-S Envs expressed as full-length proteins bound well to a number of neutralizing antibodies with discontinuous epitopes. Also, both consensus and mosaic immunogens induced significantly higher gamma interferon (IFN-γ) enzyme-linked immunosorbent spot assay (ELISpot) responses than B.1059 immunogen. Immunization with these proteins, particularly Con-S, also induced significantly higher neutralizing antibodies to viruses than B.1059 Env, primarily to tier 1 viruses. Both Con-S and mosaics stimulated more potent CD8-T cell responses against heterologous Envs than did B.1059. Both antibody and cellular data from this study strengthen the concept of using in silico-designed centralized immunogens for global HIV-1 vaccine development strategies. IMPORTANCE: There is an increasing appreciation for the importance of vaccine-induced anti-Env antibody responses for preventing HIV-1 acquisition. This nonhuman primate study demonstrates that in silico-designed global HIV-1 immunogens, designed for a human clinical trial, are capable of eliciting not only T lymphocyte responses but also potent anti-Env antibody responses.

Effect of Maraviroc Intensification on HIV-1-Specific T Cell Immunity in Recently HIV-1-Infected Individuals

Background The effect of maraviroc on the maintenance and the function of HIV-1-specific T cell responses remains unknown. Methods Subjects recently infected with HIV-1 were randomized to receive anti-retroviral treatment with or without maraviroc intensification for 48 weeks, and were monitored up to week 60. PBMC and in vitro-expanded T cells were tested for responses to the entire HIV proteome by ELISpot analyses. Intracellular cytokine staining assays were conducted to monitor the (poly)-functionality of HIV-1-specific T cells. Analyses were performed at baseline and week 24 after treatment start, and at week 60 (3 months after maraviroc discontinuation). Results Maraviroc intensification was associated with a slower decay of virus-specific T cell responses over time compared to the non-intensified regimen in both direct ex-vivo as well as in in-vitro expanded cells. The effector function profiles of virus-specific CD8+ T cells were indistinguishable between the two arms and did not change over time between the groups. Conclusions Maraviroc did not negatively impact any of the measured parameters, but was rather associated with a prolonged maintenance of HIV-1-specific T cell responses. Maraviroc, in addition to its original effect as viral entry inhibitor, may provide an additional benefit on the maintenance of virus-specific T cells which may be especially important for future viral eradication strategies.

Anti-MPER antibodies with heterogeneous neutralization capacity are detectable in most untreated HIV-1 infected individuals

Background The MPER region of the HIV-1 envelope glycoprotein gp41 is targeted by broadly neutralizing antibodies. However, the localization of this epitope in a hydrophobic environment seems to hamper the elicitation of these antibodies in HIV infected individuals. We have quantified and characterized anti-MPER antibodies by ELISA and by flow cytometry using a collection of mini gp41-derived proteins expressed on the surface of 293T cells. Longitudinal plasma samples from 35 HIV-1 infected individuals were assayed for MPER recognition and MPER-dependent neutralizing capacity using HIV-2 viruses engrafted with HIV-1 MPER sequences. Results Miniproteins devoid of the cysteine loop of gp41 exposed the MPER on 293T cell membrane. Anti-MPER antibodies were identified in most individuals and were stable when analyzed in longitudinal samples. The magnitude of the responses was strongly correlated with the global response to the HIV-1 envelope glycoprotein, suggesting no specific limitation for anti-MPER antibodies. Peptide mapping showed poor recognition of the C-terminal MPER moiety and a wide presence of antibodies against the 2F5 epitope. However, antibody titers failed to correlate with 2F5-blocking activity and, more importantly, with the specific neutralization of HIV-2 chimeric viruses bearing the HIV-1 MPER sequence; suggesting a strong functional heterogeneity in anti-MPER humoral responses. Conclusions Anti-MPER antibodies can be detected in the vast majority of HIV-1 infected individuals and are generated in the context of the global anti-Env response. However, the neutralizing capacity is heterogeneous suggesting that eliciting neutralizing anti-MPER antibodies by immunization might require refinement of immunogens to skip nonneutralizing responses.

Decreasing Proportion of Recent Infections among Newly Diagnosed HIV-1 Cases in Switzerland, 2008 to 2013 Based on Line-Immunoassay-Based Algorithms.

BACKGROUND: HIV surveillance requires monitoring of new HIV diagnoses and differentiation of incident and older infections. In 2008, Switzerland implemented a system for monitoring incident HIV infections based on the results of a line immunoassay (Inno-Lia) mandatorily conducted for HIV confirmation and type differentiation (HIV-1, HIV-2) of all newly diagnosed patients. Based on this system, we assessed the proportion of incident HIV infection among newly diagnosed cases in Switzerland during 2008-2013. METHODS AND RESULTS: Inno-Lia antibody reaction patterns recorded in anonymous HIV notifications to the federal health authority were classified by 10 published algorithms into incident (up to 12 months) or older infections. Utilizing these data, annual incident infection estimates were obtained in two ways, (i) based on the diagnostic performance of the algorithms and utilizing the relationship 'incident = true incident + false incident', (ii) based on the window-periods of the algorithms and utilizing the relationship 'Prevalence = Incidence x Duration'. From 2008-2013, 3'851 HIV notifications were received. Adult HIV-1 infections amounted to 3'809 cases, and 3'636 of them (95.5%) contained Inno-Lia data. Incident infection totals calculated were similar for the performance- and window-based methods, amounting on average to 1'755 (95% confidence interval, 1588-1923) and 1'790 cases (95% CI, 1679-1900), respectively. More than half of these were among men who had sex with men. Both methods showed a continuous decline of annual incident infections 2008-2013, totaling -59.5% and -50.2%, respectively. The decline of incident infections continued even in 2012, when a 15% increase in HIV notifications had been observed. This increase was entirely due to older infections. Overall declines 2008-2013 were of similar extent among the major transmission groups. CONCLUSIONS: Inno-Lia based incident HIV-1 infection surveillance proved useful and reliable. It represents a free, additional public health benefit of the use of this relatively costly test for HIV confirmation and type differentiation.

Dual and Opposite Effects of hRAD51 Chemical Modulation on HIV-1 Integration.

The cellular DNA repair hRAD51 protein has been shown to restrict HIV-1 integration both in vitro and in vivo. To investigate its regulatory functions, we performed a pharmacological analysis of the retroviral integration modulation by hRAD51. We found that, in vitro, chemical activation of hRAD51 stimulates its integration inhibitory properties, whereas inhibition of hRAD51 decreases the integration restriction, indicating that the modulation of HIV-1 integration depends on the hRAD51 recombinase activity. Cellular analyses demonstrated that cells exhibiting high hRAD51 levels prior to de novo infection are more resistant to integration. On the other hand, when hRAD51 was activated during integration, cells were more permissive. Altogether, these data establish the functional link between hRAD51 activity and HIV-1 integration. Our results highlight the multiple and opposite effects of the recombinase during integration and provide new insights into the cellular regulation of HIV-1 replication.

Interleukin-1- and type I interferon-dependent enhanced immunogenicity of an NYVAC-HIV-1 Env-Gag-Pol-Nef vaccine vector with dual deletions of type I and type II interferon-binding proteins.

UNLABELLED: NYVAC, a highly attenuated, replication-restricted poxvirus, is a safe and immunogenic vaccine vector. Deletion of immune evasion genes from the poxvirus genome is an attractive strategy for improving the immunogenic properties of poxviruses. Using systems biology approaches, we describe herein the enhanced immunological profile of NYVAC vectors expressing the HIV-1 clade C env, gag, pol, and nef genes (NYVAC-C) with single or double deletions of genes encoding type I (ΔB19R) or type II (ΔB8R) interferon (IFN)-binding proteins. Transcriptomic analyses of human monocytes infected with NYVAC-C, NYVAC-C with the B19R deletion (NYVAC-C-ΔB19R), or NYVAC-C with B8R and B19R deletions (NYVAC-C-ΔB8RB19R) revealed a concerted upregulation of innate immune pathways (IFN-stimulated genes [ISGs]) of increasing magnitude with NYVAC-C-ΔB19R and NYVAC-C-ΔB8RB19R than with NYVAC-C. Deletion of B8R and B19R resulted in an enhanced activation of IRF3, IRF7, and STAT1 and the robust production of type I IFNs and of ISGs, whose expression was inhibited by anti-type I IFN antibodies. Interestingly, NYVAC-C-ΔB8RB19R induced the production of much higher levels of proinflammatory cytokines (tumor necrosis factor [TNF], interleukin-6 [IL-6], and IL-8) than NYVAC-C or NYVAC-C-ΔB19R as well as a strong inflammasome response (caspase-1 and IL-1β) in infected monocytes. Top network analyses showed that this broad response mediated by the deletion of B8R and B19R was organized around two upregulated gene expression nodes (TNF and IRF7). Consistent with these findings, monocytes infected with NYVAC-C-ΔB8RB19R induced a stronger type I IFN-dependent and IL-1-dependent allogeneic CD4(+) T cell response than monocytes infected with NYVAC-C or NYVAC-C-ΔB19R. Dual deletion of type I and type II IFN immune evasion genes in NYVAC markedly enhanced its immunogenic properties via its induction of the increased expression of type I IFNs and IL-1β and make it an attractive candidate HIV vaccine vector. IMPORTANCE: NYVAC is a replication-deficient poxvirus developed as a vaccine vector against HIV. NYVAC expresses several genes known to impair the host immune defenses by interfering with innate immune receptors, cytokines, or interferons. Given the crucial role played by interferons against viruses, we postulated that targeting the type I and type II decoy receptors used by poxvirus to subvert the host innate immune response would be an attractive approach to improve the immunogenicity of NYVAC vectors. Using systems biology approaches, we report that deletion of type I and type II IFN immune evasion genes in NYVAC poxvirus resulted in the robust expression of type I IFNs and interferon-stimulated genes (ISGs), a strong activation of the inflammasome, and upregulated expression of IL-1β and proinflammatory cytokines. Dual deletion of type I and type II IFN immune evasion genes in NYVAC poxvirus improves its immunogenic profile and makes it an attractive candidate HIV vaccine vector.

Synthetic long peptide booster immunization in rhesus macaques primed with replication-competent NYVAC-C-KC induces a balanced CD4/CD8 T-cell and antibody response against the conserved regions of HIV-1.

The Thai trial (RV144) indicates that a prime-boost vaccine combination that induces both T-cell and antibody responses may be desirable for an effective HIV vaccine. We have previously shown that immunization with synthetic long peptides (SLP), covering the conserved parts of SIV, induced strong CD4 T-cell and antibody responses, but only modest CD8 T-cell responses. To generate a more balanced CD4/CD8 T-cell and antibody response, this study evaluated a pox-vector prime/SLP boost strategy in rhesus macaques. Priming with a replication-competent NYVAC, encoding HIV-1 clade C gag, pol and nef, induced modest IFNγ T-cell immune responses, predominantly directed against HIV-1 Gag. Booster immunization with SLP, covering the conserved parts of HIV-1 Gag, Pol and Env, resulted in a more than 10-fold increase in IFNγ ELISpot responses in four of six animals, which were predominantly HIV-1 Pol-specific. The animals showed a balanced polyfunctional CD4 and CD8 T-cell response and high Ab titres.

Head-to-Head Comparison of Poxvirus NYVAC and ALVAC Vectors Expressing Identical HIV-1 Clade C Immunogens in Prime-Boost Combination with Env Protein in Nonhuman Primates.

UNLABELLED: We compared the HIV-1-specific cellular and humoral immune responses elicited in rhesus macaques immunized with two poxvirus vectors (NYVAC and ALVAC) expressing the same HIV-1 antigens from clade C, Env gp140 as a trimeric cell-released protein and a Gag-Pol-Nef polyprotein as Gag-induced virus-like particles (VLPs) (referred to as NYVAC-C and ALVAC-C). The immunization protocol consisted of two doses of the corresponding poxvirus vector plus two doses of a combination of the poxvirus vector and a purified HIV-1 gp120 protein from clade C. This immunogenicity profile was also compared to that elicited by vaccine regimens consisting of two doses of the ALVAC vector expressing HIV-1 antigens from clades B/E (ALVAC-vCP1521) plus two doses of a combination of ALVAC-vCP1521 and HIV-1 gp120 protein from clades B/E (similar to the RV144 trial regimen) or clade C. The results showed that immunization of macaques with NYVAC-C stimulated at different times more potent HIV-1-specific CD4(+) T-cell responses and induced a trend toward higher-magnitude HIV-1-specific CD8(+) T-cell immune responses than did ALVAC-C. Furthermore, NYVAC-C induced a trend toward higher levels of binding IgG antibodies against clade C HIV-1 gp140, gp120, or murine leukemia virus (MuLV) gp70-scaffolded V1/V2 and toward best cross-clade-binding IgG responses against HIV-1 gp140 from clades A, B, and group M consensus, than did ALVAC-C. Of the linear binding IgG responses, most were directed against the V3 loop in all immunization groups. Additionally, NYVAC-C and ALVAC-C also induced similar levels of HIV-1-neutralizing antibodies and antibody-dependent cellular cytotoxicity (ADCC) responses. Interestingly, binding IgA antibody levels against HIV-1 gp120 or MuLV gp70-scaffolded V1/V2 were absent or very low in all immunization groups. Overall, these results provide a comprehensive survey of the immunogenicity of NYVAC versus ALVAC expressing HIV-1 antigens in nonhuman primates and indicate that NYVAC may represent an alternative candidate to ALVAC in the development of a future HIV-1 vaccine. IMPORTANCE: The finding of a safe and effective HIV/AIDS vaccine immunogen is one of the main research priorities. Here, we generated two poxvirus-based HIV vaccine candidates (NYVAC and ALVAC vectors) expressing the same clade C HIV-1 antigens in separate vectors, and we analyzed in nonhuman primates their immunogenicity profiles. The results showed that immunization with NYVAC-C induced a trend toward higher HIV-1-specific cellular and humoral immune responses than did ALVAC-C, indicating that this new NYVAC vector could be a novel optimized HIV/AIDS vaccine candidate for human clinical trials.

Once-daily dolutegravir versus darunavir plus ritonavir for treatment-naive adults with HIV-1 infection (FLAMINGO): 96 week results from a randomised, open-label, phase 3b study.

BACKGROUND: The primary analysis of the FLAMINGO study at 48 weeks showed that patients taking dolutegravir once daily had a significantly higher virological response rate than did those taking ritonavir-boosted darunavir once daily, with similar tolerability. We present secondary efficacy and safety results analysed at 96 weeks. METHODS: FLAMINGO was a multicentre, open-label, phase 3b, non-inferiority study of HIV-1-infected treatment-naive adults. Patients were randomly assigned (1:1) to dolutegravir 50 mg or darunavir 800 mg plus ritonavir 100 mg, with investigator-selected combination tenofovir and emtricitabine or combination abacavir and lamivudine background treatment. The main endpoints were plasma HIV-1 RNA less than 50 copies per mL and safety. The non-inferiority margin was -12%. If the lower end of the 95% CI was greater than 0%, then we concluded that dolutegravir was superior to ritonavir-boosted darunavir. This trial is registered with ClinicalTrials.gov, number NCT01449929. FINDINGS: Of 595 patients screened, 488 were randomly assigned and 484 included in the analysis (242 assigned to receive dolutegravir and 242 assigned to receive ritonavir-boosted darunavir). At 96 weeks, 194 (80%) of 242 patients in the dolutegravir group and 164 (68%) of 242 in the ritonavir-boosted darunavir group had HIV-1 RNA less than 50 copies per mL (adjusted difference 12·4, 95% CI 4·7-20·2; p=0·002), with the greatest difference in patients with high viral load at baseline (50/61 [82%] vs 32/61 [52%], homogeneity test p=0·014). Six participants (three since 48 weeks) in the dolutegravir group and 13 (four) in the darunavir plus ritonavir group discontinued because of adverse events. The most common drug-related adverse events were diarrhoea (23/242 [10%] in the dolutegravir group vs 57/242 [24%] in the darunavir plus ritonavir group), nausea (31/242 [13%] vs 34/242 [14%]), and headache (17/242 [7%] vs 12/242 [5%]). INTERPRETATION: Once-daily dolutegravir is associated with a higher virological response rate than is once-daily ritonavir-boosted darunavir. Dolutegravir compares favourably in efficacy and safety to a boosted darunavir regimen with nucleoside reverse transcriptase inhibitor background treatment for HIV-1-infected treatment-naive patients. FUNDING: ViiV Healthcare and Shionogi & Co.

The Depsipeptide Romidepsin Reverses HIV-1 Latency In Vivo.

UNLABELLED: Pharmacologically-induced activation of replication competent proviruses from latency in the presence of antiretroviral treatment (ART) has been proposed as a step towards curing HIV-1 infection. However, until now, approaches to reverse HIV-1 latency in humans have yielded mixed results. Here, we report a proof-of-concept phase Ib/IIa trial where 6 aviremic HIV-1 infected adults received intravenous 5 mg/m2 romidepsin (Celgene) once weekly for 3 weeks while maintaining ART. Lymphocyte histone H3 acetylation, a cellular measure of the pharmacodynamic response to romidepsin, increased rapidly (maximum fold range: 3.7-7.7 relative to baseline) within the first hours following each romidepsin administration. Concurrently, HIV-1 transcription quantified as copies of cell-associated un-spliced HIV-1 RNA increased significantly from baseline during treatment (range of fold-increase: 2.4-5.0; p = 0.03). Plasma HIV-1 RNA increased from <20 copies/mL at baseline to readily quantifiable levels at multiple post-infusion time-points in 5 of 6 patients (range 46-103 copies/mL following the second infusion, p = 0.04). Importantly, romidepsin did not decrease the number of HIV-specific T cells or inhibit T cell cytokine production. Adverse events (all grade 1-2) were consistent with the known side effects of romidepsin. In conclusion, romidepsin safely induced HIV-1 transcription resulting in plasma HIV-1 RNA that was readily detected with standard commercial assays demonstrating that significant reversal of HIV-1 latency in vivo is possible without blunting T cell-mediated immune responses. These finding have major implications for future trials aiming to eradicate the HIV-1 reservoir. TRIAL REGISTRATION: clinicaltrials.gov NTC02092116.

Immune correlates of vaccine protection against HIV-1 acquisition.

The partial efficacy reported in the RV144 HIV vaccine trial in 2009 has driven the HIV vaccine field to define correlates of risk associated with HIV-1 acquisition and connect these functionally to preventing HIV infection. Immunological correlates, mainly including CD4(+) T cell responses to the HIV envelope and Fc-mediated antibody effector function, have been connected to reduced acquisition. These immunological correlates place immunological and genetic pressure on the virus. Indeed, antibodies directed at conserved regions of the V1V2 loop and antibodies that mediate antibody-dependent cellular cytotoxicity to HIV envelope in the absence of inhibiting serum immunoglobulin A antibodies correlated with decreased HIV risk. More recently, researchers have expanded their search with nonhuman primate studies using vaccine regimens that differ from that used in RV144; these studies indicate that non-neutralizing antibodies are associated with protection from experimental lentivirus challenge as well. These immunological correlates have provided the basis for the design of a next generation of vaccine regimens to improve upon the qualitative and quantitative degree of magnitude of these immune responses on HIV acquisition.

Switching from tenofovir disoproxil fumarate to tenofovir alafenamide in antiretroviral regimens for virologically suppressed adults with HIV-1 infection: a randomised, active-controlled, multicentre, open-label, phase 3, non-inferiority study.

BACKGROUND: Antiretroviral regimens containing tenofovir disoproxil fumarate have been associated with renal toxicity and reduced bone mineral density. Tenofovir alafenamide is a novel tenofovir prodrug that reduces tenofovir plasma concentrations by 90%, thereby decreasing off-target side-effects. We aimed to assess whether efficacy, safety, and tolerability were non-inferior in patients switched to a regimen containing tenofovir alafenamide versus in those remaining on one containing tenofovir disoproxil fumarate. METHODS: In this randomised, actively controlled, multicentre, open-label, non-inferiority trial, we recruited HIV-1-infected adults from Gilead clinical studies at 168 sites in 19 countries. Patients were virologically suppressed (HIV-1 RNA <50 copies per mL) with an estimated glomerular filtration rate of 50 mL per min or greater, and were taking one of four tenofovir disoproxil fumarate-containing regimens for at least 96 weeks before enrolment. With use of a third-party computer-generated sequence, patients were randomly assigned (2:1) to receive a once-a-day single-tablet containing elvitegravir 150 mg, cobicistat 150 mg, emtricitabine 200 mg, and tenofovir alafenamide 10 mg (tenofovir alafenamide group) or to carry on taking one of four previous tenofovir disoproxil fumarate-containing regimens (tenofovir disoproxil fumarate group) for 96 weeks. Randomisation was stratified by previous treatment regimen in blocks of six. Patients and treating physicians were not masked to the assigned study regimen; outcome assessors were masked until database lock. The primary endpoint was the proportion of patients who received at least one dose of study drug who had undetectable viral load (HIV-1 RNA <50 copies per mL) at week 48. The non-inferiority margin was 12%. This study was registered with ClinicalTrials.gov, number NCT01815736. FINDINGS: Between April 12, 2013 and April 3, 2014, we enrolled 1443 patients. 959 patients were randomly assigned to the tenofovir alafenamide group and 477 to the tenofovir disoproxil fumarate group. Viral suppression at week 48 was noted in 932 (97%) patients assigned to the tenofovir alafenamide group and in 444 (93%) assigned to the tenofovir disoproxil fumarate group (adjusted difference 4·1%, 95% CI 1·6-6·7), with virological failure noted in ten and six patients, respectively. The number of adverse events was similar between the two groups, but study drug-related adverse events were more common in the tenofovir alafenamide group (204 patients [21%] vs 76 [16%]). Hip and spine bone mineral density and glomerular filtration were each significantly improved in patients in the tenofovir alafenamide group compared with those in the tenofovir disoproxil fumarate group. INTERPRETATION: Switching to a tenofovir alafenamide-containing regimen from one containing tenofovir disoproxil fumarate was non-inferior for maintenance of viral suppression and led to improved bone mineral density and renal function. Longer term follow-up is needed to better understand the clinical impact of these changes. FUNDING: Gilead Sciences.

An inhibitor of HIV-1 protease modulates constitutive eIF2α dephosphorylation to trigger a specific integrated stress response.

Inhibitors of the HIV aspartyl protease [HIV protease inhibitors (HIV-PIs)] are the cornerstone of treatment for HIV. Beyond their well-defined antiretroviral activity, these drugs have additional effects that modulate cell viability and homeostasis. However, little is known about the virus-independent pathways engaged by these molecules. Here we show that the HIV-PI Nelfinavir decreases translation rates and promotes a transcriptional program characteristic of the integrated stress response (ISR). Mice treated with Nelfinavir display hallmarks of this stress response in the liver, including α subunit of translation initiation factor 2 (eIF2α) phosphorylation, activating transcription factor-4 (ATF4) induction, and increased expression of known downstream targets. Mechanistically, Nelfinavir-mediated ISR bypassed direct activation of the eIF2α stress kinases and instead relied on the inhibition of the constitutive eIF2α dephosphorylation and down-regulation of the phophatase cofactor CReP (Constitutive Repressor of eIF2α Phosphorylation; also known as PPP1R15B). These findings demonstrate that the modulation of eIF2α-specific phosphatase cofactor activity can be a rheostat of cellular homeostasis that initiates a functional ISR and suggest that the HIV-PIs could be repositioned as therapeutics in human diseases to modulate translation rates and stress responses.

Safety and Immunogenicity of a Recombinant Adenovirus Serotype 35-Vectored HIV-1 Vaccine in Adenovirus Serotype 5 Seronegative and Seropositive Individuals.

BACKGROUND: Recombinant adenovirus serotype 5 (rAd5)-vectored HIV-1 vaccines have not prevented HIV-1 infection or disease and pre-existing Ad5 neutralizing antibodies may limit the clinical utility of Ad5 vectors globally. Using a rare Ad serotype vector, such as Ad35, may circumvent these issues, but there are few data on the safety and immunogenicity of rAd35 directly compared to rAd5 following human vaccination. METHODS: HVTN 077 randomized 192 healthy, HIV-uninfected participants into one of four HIV-1 vaccine/placebo groups: rAd35/rAd5, DNA/rAd5, and DNA/rAd35 in Ad5-seronegative persons; and DNA/rAd35 in Ad5-seropositive persons. All vaccines encoded the HIV-1 EnvA antigen. Antibody and T-cell responses were measured 4 weeks post boost immunization. RESULTS: All vaccines were generally well tolerated and similarly immunogenic. As compared to rAd5, rAd35 was equally potent in boosting HIV-1-specific humoral and cellular immunity and responses were not significantly attenuated in those with baseline Ad5 seropositivity. Like DNA, rAd35 efficiently primed rAd5 boosting. All vaccine regimens tested elicited cross-clade antibody responses, including Env V1/V2-specific IgG responses. CONCLUSIONS: Vaccine antigen delivery by rAd35 is well-tolerated and immunogenic as a prime to rAd5 immunization and as a boost to prior DNA immunization with the homologous insert. Further development of rAd35-vectored prime-boost vaccine regimens is warranted.