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Distinct dendritic cell (DC) subsets play important roles in shaping immune responses. Circulating DC precursors (pre-DCs) are more susceptible to HIV infection in vitro , which may explain the inefficiency of immune responses against HIV. However, the interplay between HIV and pre-DC is not defined in vivo. We identify human pre-DC equivalents in the cynomolgus macaque and then analyze their dynamics during simian immunodeficiency virus (SIV) infection to illustrate a sharp decrease of blood pre-DCs in early SIV infection and accumulation in lymph nodes (LNs), where they neglect to upregulate CD83/CD86 or MHC-II. Additionally, SIV infection attenuates the capacity of stimulated LN pre-DCs to produce IL-12p40. Analysis of HIV cohorts provides correlation between costimulatory molecule expression on pre-DCs and T cell activation in spontaneous HIV controllers. These findings pinpoint certain dynamics and functional changes of pre-DCs during SIV infection, providing a deeper understanding of immune dysregulation mechanisms elicited in people living with HIV. [Display omitted] • Identification of human pre-DC equivalent in macaques • Pre-DCs accumulate in the lymph node from early SIV infection • IL-12p40 production capacity of lymph node pre-DCs is attenuated in SIV infection • T cell activation in HIV controllers correlates with pre-DC costimulatory markers Gardet et al. define the human equivalent of dendritic cell precursors (pre-DCs) in a monkey model of HIV infection to demonstrate their accumulation in lymph nodes but without activating properly. This insight provides a better understanding of how HIV interferes with the immune response in humans. [ABSTRACT FROM AUTHOR]

The 2015 Cent Gardes Conference on HIV vaccines took place on October 25–27 at the Merieux Foundation Conference Center in Veyrier du Lac, near Annecy, France. The meeting reviewed progress in the development of HIV vaccines and identified new directions of future research. The field has advanced incrementally over the past year but major progress will require additional information from new clinical trials. In this article, we review the presentations on humoral immune responses to HIV, and highlight the difficulty of eliciting broadly neutralizing antibodies by vaccination. Advances in cellular immunity for HIV prevention will be reviewed separately, in a following article. [ABSTRACT FROM AUTHOR]

Summary During the early phase of replication, HIV reverse transcribes its RNA and crosses the nuclear envelope while escaping host antiviral defenses. The host factor Cyclophilin A (CypA) is essential for these steps and binds the HIV capsid; however, the mechanism underlying this effect remains elusive. Here, we identify related capsid mutants in HIV-1, HIV-2, and SIVmac that are restricted by CypA. This antiviral restriction of mutated viruses is conserved across species and prevents nuclear import of the viral cDNA. Importantly, the inner nuclear envelope protein SUN2 is required for the antiviral activity of CypA. We show that wild-type HIV exploits SUN2 in primary CD4 + T cells as an essential host factor that is required for the positive effects of CypA on reverse transcription and infection. Altogether, these results establish essential CypA-dependent functions of SUN2 in HIV infection at the nuclear envelope. [ABSTRACT FROM AUTHOR]

Abstract: Animal models of malaria, mainly mice, have made a large contribution to our knowledge of host–pathogen interactions and immune responses, and to drug and vaccine design. Non-human primate (NHP) models for malaria are admittedly under-used, although they are probably closer models than mice for human malaria; in particular, NHP models allow the use of human pathogens (Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium knowlesi). NHPs, whether natural hosts or experimentally challenged with a simian Plasmodium, can also serve as robust pre-clinical models. Some simian parasites are closely related to a human counterpart, with which they may share a common ancestor, and display similar major features with the human infection and pathology. NHP models allow longitudinal studies, from the early events following sporozoite inoculation to the later events, including analysis of organs and tissues, particularly liver, spleen, brain and bone marrow. NHP models have one other significant advantage over mouse models: NHPs are our closest relatives and thus their biology is very similar to ours. Recently developed in vivo imaging tools have provided insight into malaria parasite infection and disease in mouse models. One advantage of these tools is that they limit the need for invasive procedures, such as tissue biopsies. Many such technologies are now available for NHP studies and provide new opportunities for elucidating host/parasite interactions. The aim of this review is to bring the malaria community up to date on what is currently possible and what soon will be, in terms of in vivo imaging in NHP models of malaria, to consider the pros and the cons of the various techniques, and to identify challenges. [Copyright &y& Elsevier]

The widely administered Mycobacterium bovis BCG is an attractive live vector for the development of AIDS vaccines. We explored immune responses induced in cynomolgus macaques to rBCG–SIV3, a mixture of three recombinant BCG strains expressing the SIVmac251 nef, gag and env genes. After a single intradermal (ID) inoculation, circulating blood cells from rBCG–SIV3-vaccinated monkeys exhibited CTL responses targeted against the three antigens and interferon-gamma (IFNγ) secretion was observed. A rectal or oral boosting dose of rBCG–SIV3 elicited anti-SIV IgAs in the rectum of vaccinated monkeys and increased IFNγ secretion by circulating blood cells. Despite a good response against the vector, rBCG–SIV3 administration did not induce IgG antibody responses or lymphoproliferation against the SIV antigens in blood. This could be due to the lack of in vivo persistence of the recombinant BCG strains that were used. Rectal challenge with fully pathogenic SIVmac251-infected all animals. However, after viral challenge, anti-SIV cellular and antibody responses were higher in rBCG–SIV3 monkeys than in controls indicating that the vaccine induced anti-SIV CD4+ T-cell memory. [Copyright &y& Elsevier]

Virus-specific CD8+ T cells play an important role in controlling viral replication during acute primary infection. At this early stage, mucosal tissues represent a major site of viral replication. Therefore, the presence of functional virus-specific CD8+ effector T cells in the mucosa during primary infection is a key issue in the pathogenesis of infection. In order to evaluate the extent of this response, six rhesus macaques were infected with simian immunodeficiency virus (SIV)mac251 and sacrificed on day 28 following infection. The functional activity of SIV-effector CD8+ T cells was evaluated by means of a γ-IFN ELISpot assay with autologous cells expressing SIV env, gag, pol and nef genes as antigen-presenting cells. This evaluation was performed on PBMCs, spleen, peripheral lymph node, gut-associated lymph node and lamina propria lymphocytes isolated from different mucosal sites. In parallel, the cell-associated viral load was quantified in all these tissues. Five macaques had γ-IFN SIV-specific CD8+ T cells in PBMCs and/or lymph nodes. However, in these macaques, these CD8+ T cells were only present in seven mucosal sites out of 24 tested (the lamina propria lymphocytes of the duodenum, jejunum, ileum and colon were evaluated separately for each animal), whereas they were detected in all corresponding gut-associated lymph nodes. In addition, the mean frequency of SIV-specific γ-IFN-secreting CD8+ T cells was 117 ± 228 per 106 cells in the lamina propria vs. 958 ± 1184 in gut associated lymph nodes (P = 0.001). No overall correlation was observed between the CD8+ T-cell activity and the viral load: among the 17 mucosal sites in which the virus was isolated, no specific activity was detected in 13 sites. In conclusion, these data indicate that the frequencies of SIV-specific γ-IFN-secreting CD8+ T cells are low in the mucosa during early primary infection. This may be of importance with regard to the intense viral replication observed in the mucosa at this stage. [Copyright &y& Elsevier]

Purinergic receptors and nucleotide-binding domain leucine-rich repeat containing (NLR) proteins have been shown to control viral infection. Here, we show that the NLR family member NLRP3 and the purinergic receptor P2Y2 constitutively interact and regulate susceptibility to HIV-1 infection. We found that NLRP3 acts as an inhibitory factor of viral entry that represses F-actin remodeling. The binding of the HIV-1 envelope to its host cell receptors (CD4, CXCR4, and/or CCR5) overcomes this restriction by stimulating P2Y2. Once activated, P2Y2 enhances its interaction with NLRP3 and stimulates the recruitment of the E3 ubiquitin ligase CBL to NLRP3, ultimately leading to NLRP3 degradation. NLRP3 degradation is permissive for PYK2 phosphorylation (PYK2Y402∗) and subsequent F-actin polymerization, which is required for the entry of HIV-1 into host cells. Taken together, our results uncover a mechanism by which HIV-1 overcomes NLRP3 restriction that appears essential for the accomplishment of the early steps of HIV-1 entry. • NLRP3 and P2Y2 interact and regulate susceptibility to HIV-1 infection • NLRP3 is an intrinsic inhibitory factor for HIV-1 that represses F-actin remodeling • HIV-1 Env binding to host receptors overcomes NLRP3 restriction by activating P2Y2 • P2Y2 activation leads to CBL-mediated NLRP3 degradation and favors viral entry Paoletti et al. identified a constitutive interaction between NLRP3 and P2Y2 that regulates HIV-1 entry into target cells. They revealed that NLRP3 represses viral entry by impairing F-actin reorganization. HIV-1 overcomes this host cellular resistance by inducing NLRP3 degradation through the activation of P2Y2-dependent signaling pathway. [ABSTRACT FROM AUTHOR]

Chest X-ray (CXR), computed tomography (CT), and positron emission tomography–computed tomography (PET-CT) are noninvasive imaging techniques widely used in human and veterinary pulmonary research and medicine. These techniques have recently been applied in studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-exposed non-human primates (NHPs) to complement virological assessments with meaningful translational readouts of lung disease. Our review of the literature indicates that medical imaging of SARS-CoV-2-exposed NHPs enables high-resolution qualitative and quantitative characterization of disease otherwise clinically invisible and potentially provides user-independent and unbiased evaluation of medical countermeasures (MCMs). However, we also found high variability in image acquisition and analysis protocols among studies. These findings uncover an urgent need to improve standardization and ensure direct comparability across studies. In non-human primates (NHPs), characteristic radiographic abnormalities (best observed by high-resolution imaging), combined with concordant immunological, virological, and lung histopathological findings, mirror mild-to-moderate human disease. Noninvasive medical imaging can visualize otherwise 'silent' disease at high resolution and generates quantifiable measurements that are particularly important in sublethal models, providing an essential complement to standard immunological, virological, and pathological assays, which can only be performed as snapshots (not longitudinally) or may be difficult to perform. The incorporation of advanced medical imaging tools in NHP studies for coronavirus disease 2019 (COVID-19) research is not without challenges, including high experimental costs due to the limited availability of equipment in high containment environments, frequency of anesthesia events required for imaging, and the number of animals that can practically be imaged at a single time point. [ABSTRACT FROM AUTHOR]

• NHPs represent the best animal model for human immunology and for the major respiratory infections pathophysiology. • NHPs allow controlled pathogen exposure and monitoring, which facilitates treatments and vaccines evaluation. • Whole-body imaging allows respiratory infectious diseases monitoring in NHP in a very similar way to humans. Respiratory pathogens represent a great burden for humanity and a potential source of new pandemics, as illustrated by the recent emergence of coronavirus disease 2019 (COVID-19). In recent decades, biotechnological advances have led to the development of numerous innovative therapeutic molecules and vaccine immunogens. However, we still lack effective treatments and vaccines against many respiratory pathogens. More than ever, there is a need for a fast, predictive, preclinical pipeline, to keep pace with emerging diseases. Animal models are key for the preclinical development of disease management strategies. The predictive value of these models depends on their ability to reproduce the features of the human disease, the mode of transmission of the infectious agent and the availability of technologies for monitoring infection. This review focuses on the use of non-human primates as relevant preclinical models for the development of prevention and treatment for human respiratory infections. [ABSTRACT FROM AUTHOR]

Variety of conventional vaccine strategies tested against HIV-1 have failed to induce protection against HIV acquisition or durable control of viremia. Therefore, innovative strategies that can induce long lasting protective immunity against HIV chronic infection are needed. Recently, we developed an integration-defective HIV lentiDNA vaccine that undergoes a single cycle of replication in target cells in which most viral antigens are produced. A single immunization with such lentiDNA induced long-lasting T-cell and modest antibody responses in cynomolgus macaques. Here eighteen months after this single immunization, all animals were subjected to repeated low dose intra-rectal challenges with a heterologous pathogenic SIVmac251 isolate. Although the viral set point in SIVmac-infected cynomolgus is commonly lower than that seen in Indian rhesus macaques, the vaccinated group of macaques displayed a two log reduction of peak of viremia followed by a progressive and sustained control of virus replication relative to control animals. This antiviral control correlated with antigen-specific CD4+ and CD8+ T cells with high capacity of recall responses comprising effector and central memory T cells but also memory T cell precursors. This is the first description of SIV control in NHP model infected at 18 months following a single immunization with a non-integrative single cycle lentiDNA HIV vaccine. While not delivering sterilizing immunity, our single immunization strategy with a single-cycle lentivector DNA vaccine appears to provide an interesting and safe vaccine platform that warrants further exploration. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract This work investigates the impact of vaginal ring size and drug loading on the in vitro release, safety, ease of fit, and pharmacokinetics in cynomolgus macaques of matrix-type silicone elastomer vaginal rings containing a combination of the non-nucleoside reverse transcriptase inhibitor dapivirine and the protease inhibitor darunavir. Drug-free and drug-loaded vaginal rings having three different geometries were manufactured by reaction injection molding. In vitro drug release was assessed using both a solvent/water mixture and a vaginal fluid simulant. Macaques fitted with drug-free vaginal rings for 28 days were assessed by colposcopy, cytological evaluation of cervico-vaginal lavage and histological evaluation of tissue after ring removal. The 20 × 4.5 mm combination ring, deemed most appropriate for vaginal fit and comfort in the macaques, was evaluated for pharmacokinetics over 28 days. Substantial differences were observed in the in vitro release profiles between the three ring sizes. However, these differences were not manifest in vivo , where measured drug concentrations after 20 × 4.5 mm ring use were not significantly different from those reported previously with a 25 × 6 mm ring. These results suggest that ring placement and fit is an important species-specific study parameter that should be optimised prior to pharmacokinetic testing. [ABSTRACT FROM AUTHOR]

We evaluated the immunogenicity of a prime/boost vaccine strategy combining 5 lipopeptides (HIV-Lipo-5) and a recombinant modified vaccinia virus Ankara (rMVA-HIV) in cynomolgus macaques. Both of these vaccine components deliver HIV LAI Gag, Pol, and Nef antigens. Systemic and local safety was excellent in all groups. Immunization with HIV-Lipo-5 alone induced significant serum anti-HIV antibody titers which were not modified by rMVA-HIV immunization. However, induction of T-cell responses, as measured by IFNγ and IL-2 producing cells upon short-term stimulation with HIV peptide pools, required combined immunization with rMVA-HIV. Responses were preferentially observed against Gag antigen. Interestingly, HIV-Lipo-5 efficiently primed HIV induced T-cell responses upon the injection of rMVA-HIV, which may help to reduce the required number of vector injections. Our results provide a rationale for the use of a strategy involving HIV-Lipo-5 priming followed by rMVA-HIV booster immunization as a prophylactic or therapeutic vaccine approach against HIV infection and AIDS. [ABSTRACT FROM AUTHOR]

The miniCD4 M48U1 was formulated into thermosensitive and mucoadhesive pluronic® hydrogels as anti-HIV-1 microbicide. The release kinetics of M48U1 from F127/HPMC (20/1wt%) and F127/F68/HPMC (22.5/2.5/1wt%) studied during 24h by using Franz diffusion cells showed that HEC hydrogel (1.5wt%) used as control released 93% of the peptide, while about 25% of M48U1 remained in pluronic® hydrogels. The formulation of M48U1 in pluronic® hydrogels ensures a local delivery because no diffusion of the peptide was detected through vaginal Cynomolgus macaque mucosa using Ussing chamber. Finally, toxicological studies showed no significant difference in the HeLa cell viability of the pluronic® hydrogels in comparison with HEC and phosphate buffer saline. [ABSTRACT FROM AUTHOR]

Abstract: Background: The immunodeficiency defining AIDS results from a progressive decline in the number of CD4+ T cells. Although no single viral protein is likely to be the sole effector of immune impairment, the gp41 envelope protein is believed to contribute significantly to AIDS pathogenesis. We have shown that 3S, a unique motif of gp41, is highly conserved in HIV-1 strains and specifically induces NKp44L, a ligand of the natural cytotoxicity receptor NKp44, on CD4+ T cells, rendering them sensitive to NK lysis. We therefore hypothesized that a 3S/gp41 vaccine strategy designed to modulate the NK cell compartment might improve CD4+ T cell resistance, independently of any effect on viral load. Methods: Nine macaques were chronically infected with the SHIV163P3; four were then immunized with the 3S/gp41 peptide and five with the carrier alone. Frequency of CD4+ T cell subsets, proliferation, cell activation and apoptosis were analyzed in the periphery and the lymph nodes, spleen and rectum by flow cytometry. Results: The anti-3S antibodies prevented NKp44L expression on CD4+ T cells in vivo and subsequently preserved the CD4+ central memory T cells in 3S/gp41-vaccinated animals. They also limited the NK cytotoxic activity against autologous CD4+ T cells, the cell activation, the proliferation, and the apoptosis in peripheral blood and secondary lymphoid tissues remained intact. Conclusion: These data suggest a new paradigm for AIDS vaccine development, aimed at generating specific responses to protect a specific subset of CD4+ T cells from attack by activated NK cells. [Copyright &y& Elsevier]

Abstract: The transcriptional transactivator (Tat) of HIV-1 is regarded as an attractive target for the development of an AIDS vaccine. However, investigations have suggested that Tat is poorly immunogenic and prompted us to develop a strategy to increase its ability to raise an immune response. The strategy is based on stabilization of Tat using sulfated sugars, previously proven to boost its humoral immunogenic potency, in mice. We have now examined the pattern of immune response raised by two Tat-stabilized proteins previously mixed with Alum, in mice and macaques. We found that BALB/c and DBA/2 mice raise a Th2 immune response that contrasts with the mixed Th1/Th2 response observed in cynomolgus macaques indicating that the profile of response found in mice cannot be extrapolated to macaques. We thoroughly analyzed the macaque anti-Tat immune response and observed that the anti-Tat antibodies appear after only one immunization and that their titers remain elevated up to 8 weeks after the last injection. We found a similar behavior for the cellular immune response. Furthermore, we observed that approximately 50% of the IFN-γ-secreting Tat-specific T-cells are CD8 lymphocytes. Last, we observed that the macaque sera neutralize the transactivating activity of Tat. This analysis shows that the two Tat-stabilized preparations raise a potent and long-lasting humoral and cellular immune response in cynomolgus macaque and opens an avenue to investigate whether a strong anti-Tat immune response can protect non-human primates against a viral challenge. [Copyright &y& Elsevier]

Abstract: CBD1 peptide (SLEQIWNNMTWMQWDK), corresponding to the consensus caveolin-1 binding domain in HIV-1 envelope glycoprotein gp41, elicits the production of antibodies that inhibit infection of primary CD4+ T lymphocytes by various primary HIV-1 isolates. Here the immunogenicity of the CBD1 peptide was investigated in cynomolgus macaques using adjuvants that are acceptable for human use. In the first set of studies, macaques were immunized with the CBD1 peptide in association with muramyl dipeptide derivative MDP-Lys(L18) combined with the oil-in-water emulsion, MF-59. After five immunizations at 4 weeks interval, the antibody titer against the CBD1 peptide was found to be either medium, poor, weak or none, thus suggesting that the CBD1 immune response might be restricted by the major histocompatibility complex (MHC) class II molecules. In the second set of studies therefore, macaques were immunized with the CBD1 peptide in association with the ‘promiscuous’ T cell epitope from the tetanus toxin, either as free peptides or covalently linked with the dilysine linker using CpG ODN and Montanide ISA 51 as adjuvants. This latter immunization procedure boosted markedly the anti-CBD1 antibody response, since even the non-responders generated high-titered peptide-specific antibodies. Moreover, co-immunization of the CBD1 and the T helper epitope as free peptides seemed to be favorable for the production of neutralizing antibodies, with 50% inhibition of HIV-1 infection occurring at 300–400-fold dilution of the immune sera. Finally, neutralizing and non-neutralizing immune macaque sera could be differentiated by the profile of cross-reactivity with overlapping CBD1-related peptides in ELISA. Taken together, our results demonstrate that the CBD1 peptide is immunogenic in macaques and that an eventual MHC-restriction could be overcome by the administration with an appropriate T helper epitope. [Copyright &y& Elsevier]

Summary: Using the experimental infection of cynomolgus macaques with simian immunodeficiency virus (SIV) as a model of human immunodeficiency virus infection in humans, we studied the immunogenicity and protective efficacy of a vaccine strategy combining DNA, the modified recombinant vaccinia virus strain Ankara (MVA) and Semliki Forest virus (SFV) expressing gag, pol, env, tat, rev and nef from SIV. Although this immunization strategy induced moderate immune responses, the control of pathogenic SIVmac251 infection following mucosal challenge was clearly improved by vaccination. The viral load in vaccinated animals was reduced by 2 logs during the acute phase of infection and, in five of the six macaques, viral load fell below the detection limit at set point. No correlates of immune protection were identified, but SIV-specific T-cell responses were detected earlier in vaccinated animals than in controls. These results highlight the power of live attenuated virus vectors for vaccination strategies. [Copyright &y& Elsevier]

Abstract: Modified vaccinia virus Ankara (MVA) is a potent vaccine vector, which proved its safety, immunogenity and efficacy in preclinical and clinical studies. The rational for the development of a vaccine against HIV based on the regulatory protein Nef delivered by MVA combined with a V2-deleted Env protein is discussed. [Copyright &y& Elsevier]

Recent efforts to design an human immunodeficiency virus type 1 (HIV-1) vaccine candidate have focused on means of eliciting anti-viral T-cell responses. We tried to improve the immunogenicity of DNA vaccines by designing hybrid DNA constructs encoding hepatitis B surface antigen (HBsAg) fused to antigenic domains of simian/human immunodeficiency virus (SHIV 89.6P). Immunisation with hybrid DNA induced both effector and long-lasting precursor T-cells. Following boosting with a recombinant modified vaccinia Ankara (rMVA) producing full-length SIV and HIV antigens, it appeared that priming with hybrid DNA had increased virus-specific T-cell responses in terms of both the number of virus-specific IFN-γ-secreting T-cells and virus-specific lymphoproliferation. After intrarectal challenge with SHIV 89.6P, immunised animals demonstrated early control of SHIV 89.6P replication and stable CD4+ T-cell counts. [Copyright &y& Elsevier]

Recent contributions have demonstrated that actively secreted Tat protein plays an important functional role in human immunodeficiency virus-1 (HIV-1) infection and that Tat antibodies might interfere with disease progression by blocking the protein extracellularly. In this context we have studied the recognition of several Tat mutants as well as various synthetic Tat fragments by anti-Tat monoclonal antibodies and by IgG antibodies from a large collection of slow and fast-progressor infected individuals. We have also tested the sera from simian/human immunodeficiency virus (SHIV)-infected macaques with these Tat peptides. Important differences were found between long-term non-progressors and fast-progressors, and between human and monkey sera in terms of antibody specificity. Rabbits and macaques were immunised with several Tat peptides and we found that certain antibody subsets from immunised animals recognised the cognate protein Tat and had the capacity to inhibit Tat-induced apoptosis of T cells. Such antibodies might be important for controlling Tat-induced death in cells uninfected by HIV-1. [Copyright &y& Elsevier]