Assessing the Impact of Persistent HIV Infection on Innate Lymphoid Cells Using In Vitro Models.

Pathogens that persist in their host induce immune dysfunctions even in the absence of detectable replication. To better understand the phenotypic and functional changes that persistent infections induce in sentinel innate immune cells, we developed human PBMC-based HIV models of persistent infection. Autologous nonactivated PBMCs were cocultured with chronically infected, acutely infected, or uninfected cells and were then analyzed by unsupervised high-dimensional flow cytometry. Using this approach, we identified prevalent patterns of innate immune dysfunctions associated with persistent HIV infections that at least in part mirror immune dysfunctions observed in patients. In one or more models of chronic infection, bystander CD16+ NK cells expressing markers of activation, such as CD94, CD45RO, CD62L, CD69, CD25, and immune checkpoints PD1, Tim3, TIGIT, NKG2A and Lag3, were significantly reduced. Conversely, helper ILC subsets expressing PDL1/PDL2 were significantly enriched in chronic infection compared with either uninfected or acute infection, suggesting that chronic HIV-1 infection was associated with an inhibitory environment for bystander ILC and NK subsets. The cell-based models of persistent infection that we describe here provide versatile tools to explore the molecular mechanisms of these immune dysfunctions and unveil the contribution of innate immunity in sustaining pathogen persistence.

Identifying enhancers of innate immune signaling as broad-spectrum antivirals active against emerging viruses.

The increasingly frequent outbreaks of pathogenic viruses have underlined the urgent need to improve our arsenal of antivirals that can be deployed for future pandemics. Innate immunity is a powerful first line of defense against pathogens, and compounds that boost the innate response have high potential to act as broad-spectrum antivirals. Here, we harnessed localization-dependent protein-complementation assays (called Alpha Centauri) to measure the nuclear translocation of interferon regulatory factors (IRFs), thus providing a readout of innate immune activation following viral infection that is applicable to high-throughput screening of immunomodulatory molecules. As proof of concept, we screened a library of kinase inhibitors on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and identified Gilteritinib as a powerful enhancer of innate responses to viral infection. This immunostimulatory activity of Gilteritinib was found to be dependent on the AXL-IRF7 axis and results in a broad and potent antiviral activity against unrelated RNA viruses.

Cotrimoxazole versus sulfadoxine-pyrimethamine for intermittent preventive treatment of malaria in HIV-infected pregnant women in Bangui, Central African Republic: A pragmatic randomised controlled trial.

OBJECTIVE: The main objective of the MACOMBA (Maternity and Control of Malaria-HIV co-infection in Bangui) trial was to show that cotrimoxazole (CTX) is more effective than sulphadoxine-pyremethamine-IPTp (IPTp-SP) to prevent placental malaria infection (primary end point) among HIV-positive pregnant women with a CD4+ count ≥350 cells/mm3 in Bangui, CAR. METHODS: MACOMBA is a multicentre, open-label randomised trial conducted in four maternity hospitals in Bangui. Between 2013 and 2017, 193 women were randomised and 112 (59 and 53 in CTX and IPTp-SP arms, respectively) were assessed for placental infection defined by microscopic parasitaemia or PCR. RESULTS: Thirteen women had a placental infection: five in the CTX arm (one by microscopic placental parasitaemia and four by PCR) and eight by PCR in the SP-IPTp (8.5% vs. 15.1%, p = 0.28). The percentage of newborns with low birthweight (<2500 g) did not differ statistically between the two arms. Self-reported compliance to CTX prophylaxis was good. There was a low overall rate of adverse events in both arms. CONCLUSION: Although our results do not allow us to conclude that CTX is more effective, drug safety and good compliance among women with this treatment favour its widespread use among HIV-infected pregnant women, as currently recommended by WHO.

RanBP2 regulates the anti-retroviral activity of TRIM5α by SUMOylation at a predicted phosphorylated SUMOylation motif.

TRIM5α is a cytoplasmic restriction factor that blocks post-entry retroviral infection. Evidence suggests that its antiviral activity can be regulated by SUMO, but how this is achieved remains unknown. Here, we show that TRIM5α forms a complex with RanGAP1, Ubc9, and RanBP2 at the nuclear pore, and that RanBP2 E3 SUMO ligase promotes the SUMOylation of endogenous TRIM5α in the cytoplasm. Loss of RanBP2 blocked SUMOylation of TRIM5α, altered its localization in primary cells, and suppressed the antiviral activity of both rhesus and human orthologs. In cells, human TRIM5α is modified on K84 within a predicted phosphorylated SUMOylation motif (pSUM) and not on K10 as found in vitro. Non-modified TRIM5α lacked antiviral activity, indicating that only SUMOylated TRIM5α acts as a restriction factor. This work illustrates the importance of the nuclear pore in intrinsic antiviral immunity, acting as a hub where virus, SUMO machinery, and restriction factors can meet.

Immunogenicity and Safety of Yellow Fever Vaccine in Allogeneic Hematopoietic Stem Cell Transplant Recipients After Withdrawal of Immunosuppressive Therapy.

As a live attenuated vaccine, yellow fever vaccine (YFV) is not routinely performed after allogeneic hematopoietic stem cell transplant (HSCT) despite it being the only efficient preventive therapy. We retrospectively identified 21 HSCT recipients immunized with YFV at a median of 39 months after HSCT and a median of 33 months after withdrawal of immunosuppression without any side effects. Eighteen evaluable patients had protective immunity after YFV. We also observed that a third of the recipients vaccinated with YFV before HSCT had persistent protective immunity after HSCT.

Endogenous TRIM5α Function Is Regulated by SUMOylation and Nuclear Sequestration for Efficient Innate Sensing in Dendritic Cells.

During retroviral infection, viral capsids are subject to restriction by the cellular factor TRIM5α. Here, we show that dendritic cells (DCs) derived from human and non-human primate species lack efficient TRIM5α-mediated retroviral restriction. In DCs, endogenous TRIM5α accumulates in nuclear bodies (NB) that partly co-localize with Cajal bodies in a SUMOylation-dependent manner. Nuclear sequestration of TRIM5α allowed potent induction of type I interferon (IFN) responses during infection, mediated by sensing of reverse transcribed DNA by cGAS. Overexpression of TRIM5α or treatment with the SUMOylation inhibitor ginkgolic acid (GA) resulted in enforced cytoplasmic TRIM5α expression and restored efficient viral restriction but abrogated type I IFN production following infection. Our results suggest that there is an evolutionary trade-off specific to DCs in which restriction is minimized to maximize sensing. TRIM5α regulation via SUMOylation-dependent nuclear sequestration adds to our understanding of how restriction factors are regulated.

Effectiveness of two antifolate prophylactic strategies against malaria in HIV-positive pregnant women in Bangui, Central African Republic: study protocol for a randomized controlled trial (MACOMBA).

BACKGROUND: Co-infection with malaria parasite and HIV is an emerging public health problem in tropical areas, particularly in pregnant women, and management of the concurrent effects of these two infections is challenging. Co-trimoxazole is a sulfamide preparation used to prevent opportunistic infections in HIV-infected patients, and many studies have reported that it has significant activity against malaria. As the efficacy of intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine (SP) against malaria is decreasing, co-trimoxazole might be an alternative for preventing malaria among HIV-infected populations. The aim of this study is to compare the effectiveness of SP-IPT, which is recommended for the prevention of malaria during pregnancy in the Central African Republic, with that of a daily dose of co-trimoxazole against P. falciparum infections among HIV-infected pregnant women in Bangui, the capital of the Central African Republic. METHODS/DESIGN: The MACOMBA study (MAternity and COntrol of Malaria-HIV co-infection in BAngui) is a multicentre open-label randomized clinical trial conducted at four maternity hospitals in Bangui. All HIV-infected pregnant women presenting for an antenatal clinic visit between the weeks 16 and 28 of amenorrhoea, with a CD4 count of more than 350 cells/mm3, will be eligible. All the women will provide written consent before being enrolled in the study and will then be randomly allocated to either SP-IPT (25 mg of sulfadoxine and 1.25 mg of pyrimethamine) or daily co-trimoxazole doses (960 mg per dose). The primary end-point is the placental malaria parasitaemia rate at delivery. Other main outcome measures include the number of malaria episodes during pregnancy, safety, and treatment compliance. Furthermore, the frequency of molecular resistance markers dhfr and dhps will be measured. DISCUSSION: In this trial, we seek to confirm whether co-trimoxazole is operationally suitable to replace SP-IPT in order to prevent malaria among pregnant women infected with HIV in the Central African Republic. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01746199.

A nonintegrative lentiviral vector-based vaccine provides long-term sterile protection against malaria.

Trials testing the RTS,S candidate malaria vaccine and radiation-attenuated sporozoites (RAS) have shown that protective immunity against malaria can be induced and that an effective vaccine is not out of reach. However, longer-term protection and higher protection rates are required to eradicate malaria from the endemic regions. It implies that there is still a need to explore new vaccine strategies. Lentiviral vectors are very potent at inducing strong immunological memory. However their integrative status challenges their safety profile. Eliminating the integration step obviates the risk of insertional oncogenesis. Providing they confer sterile immunity, nonintegrative lentiviral vectors (NILV) hold promise as mass pediatric vaccine by meeting high safety standards. In this study, we have assessed the protective efficacy of NILV against malaria in a robust pre-clinical model. Mice were immunized with NILV encoding Plasmodium yoelii Circumsporozoite Protein (Py CSP) and challenged with sporozoites one month later. In two independent protective efficacy studies, 50% (37.5-62.5) of the animals were fully protected (p = 0.0072 and p = 0.0008 respectively when compared to naive mice). The remaining mice with detectable parasitized red blood cells exhibited a prolonged patency and reduced parasitemia. Moreover, protection was long-lasting with 42.8% sterile protection six months after the last immunization (p = 0.0042). Post-challenge CD8+ T cells to CSP, in contrast to anti-CSP antibodies, were associated with protection (r = -0.6615 and p = 0.0004 between the frequency of IFN-g secreting specific T cells in spleen and parasitemia). However, while NILV and RAS immunizations elicited comparable immunity to CSP, only RAS conferred 100% of sterile protection. Given that a better protection can be anticipated from a multi-antigen vaccine and an optimized vector design, NILV appear as a promising malaria vaccine.