The multifaceted nature of HIV tissue reservoirs.

PURPOSE OF REVIEW: To underline the complexity and the heterogeneity of the HIV reservoir. RECENT FINDINGS: While lymphoid tissues (spleen, lymph nodes, gut-associated lymphoid tissue) harbor specific subsets of specialized CD4 +  T cells enriched in HIV-infected cells, non-CD4 +  T cell reservoirs such as tissue-resident macrophages and dendritic cells have also been implicated to contribute to viral persistence. Moreover, studies have applied highly sensitive tools to detect transcriptional activity within HIV-infected cells during prolonged ART and revealed a broader spectrum of transcriptional activity for proviruses than previously thought. Finally, while a combination of factors might be involved in the regulation of HIV persistence within different tissues and remains to be fully elucidated, recent results from autopsy samples of HIV-infected ART suppressed individuals indicate extensive clonality of HIV reservoirs in multiple tissues and suggest that the recirculation of HIV-infected cells and their local expansions in tissues may also contribute to the complexity of the HIV reservoirs in humans. SUMMARY: HIV persistence in blood and multiple tissues despite long-standing and potent therapy is one of the major barriers to a cure. Given that the HIV reservoir is established early and is highly complex based on its composition, viral diversity, tissue distribution, transcriptional activity, replication competence, migration dynamics and proliferative potential across the human body and possible compartmentalization in specific tissues, combinatorial therapeutic approaches are needed that may synergize to target multiple viral reservoirs to achieve a cure for HIV infection.

The HIV-1 reservoir landscape in persistent elite controllers and transient elite controllers.

BACKGROUNDPersistent controllers (PCs) maintain antiretroviral-free HIV-1 control indefinitely over time, while transient controllers (TCs) eventually lose virological control. It is essential to characterize the quality of the HIV reservoir in terms of these phenotypes in order to identify the factors that lead to HIV progression and to open new avenues toward an HIV cure.METHODSThe characterization of HIV-1 reservoir from peripheral blood mononuclear cells was performed using next-generation sequencing techniques, such as full-length individual and matched integration site proviral sequencing (FLIP-Seq; MIP-Seq).RESULTSPCs and TCs, before losing virological control, presented significantly lower total, intact, and defective proviruses compared with those of participants on antiretroviral therapy (ART). No differences were found in total and defective proviruses between PCs and TCs. However, intact provirus levels were lower in PCs compared with TCs; indeed the intact/defective HIV-DNA ratio was significantly higher in TCs. Clonally expanded intact proviruses were found only in PCs and located in centromeric satellite DNA or zinc-finger genes, both associated with heterochromatin features. In contrast, sampled intact proviruses were located in permissive genic euchromatic positions in TCs.CONCLUSIONSThese results suggest the need for, and can give guidance to, the design of future research to identify a distinct proviral landscape that may be associated with the persistent control of HIV-1 without ART.FUNDINGInstituto de Salud Carlos III (FI17/00186, FI19/00083, MV20/00057, PI18/01532, PI19/01127 and PI22/01796), Gilead Fellowships (GLD22/00147). NIH grants AI155171, AI116228, AI078799, HL134539, DA047034, MH134823, amfAR ARCHE and the Bill and Melinda Gates Foundation.

Myeloid-Derived Suppressor-like Cells as a Prognostic Marker in Critically Ill Patients: Insights from Experimental Endotoxemia and Intensive Care Patients.

Patients admitted to the intensive care unit (ICU) often experience endotoxemia, nosocomial infections and sepsis. Polymorphonuclear and monocytic myeloid-derived suppressor cells (PMN-MDSCs and M-MDSCs) can have an important impact on the development of infectious diseases, but little is known about their potential predictive value in critically ill patients. Here, we used unsupervised flow cytometry analyses to quantify MDSC-like cells in healthy subjects challenged with endotoxin and in critically ill patients admitted to intensive care units and at risk of developing infections. Cells phenotypically similar to PMN-MDSCs and M-MDSCs increased after endotoxin challenge. Similar cells were elevated in patients at ICU admission and normalized at ICU discharge. A subpopulation of M-MDSC-like cells expressing intermediate levels of CD15 (CD15int M-MDSCs) was associated with overall mortality (p = 0.02). Interestingly, the high abundance of PMN-MDSCs and CD15int M-MDSCs was a good predictor of mortality (p = 0.0046 and 0.014), with area under the ROC curve for mortality of 0.70 (95% CI = 0.4-1.0) and 0.86 (0.62-1.0), respectively. Overall, our observations support the idea that MDSCs represent biomarkers for sepsis and that flow cytometry monitoring of MDSCs may be used to risk-stratify ICU patients for targeted therapy.

Deciphering factors linked with reduced SARS-CoV-2 susceptibility in the Swiss HIV Cohort Study.

BACKGROUND: Factors influencing susceptibility to SARS-CoV-2 remain to be resolved. Using data of the Swiss HIV Cohort Study (SHCS) on 6,270 people with HIV (PWH) and serologic assessment for SARS-CoV-2 and circulating-human-coronavirus (HCoV) antibodies, we investigated the association of HIV-related and general parameters with SARS-CoV-2 infection. METHODS: We analyzed SARS-CoV-2 PCR-tests, COVID-19 related hospitalizations, and deaths reported to the SHCS between January 1, 2020 and December 31, 2021. Antibodies to SARS-CoV-2 and HCoVs were determined in pre-pandemic (2019) and pandemic (2020) bio-banked plasma and compared to HIV-negative individuals. We applied logistic regression, conditional logistic regression, and Bayesian multivariate regression to identify determinants of SARS-CoV-2 infection and Ab responses to SARS-CoV-2 in PWH. RESULTS: No HIV-1-related factors were associated with SARS-CoV-2 acquisition. High pre-pandemic HCoV antibodies were associated with a lower risk of subsequent SARS-CoV-2 infection and with higher SARS-CoV-2 antibody responses upon infection. We observed a robust protective effect of smoking on SARS-CoV-2-infection risk (aOR= 0.46 [0.38,0.56], p=2.6*10-14), which occurred even in previous smokers, and was highest for heavy smokers. CONCLUSIONS: Our findings of two independent protective factors, smoking and HCoV antibodies, both affecting the respiratory environment, underscore the importance of the local immune milieu in regulating susceptibility to SARS-CoV-2.

Lymph node dendritic cells harbor inducible replication-competent HIV despite years of suppressive ART.

Although gut and lymph node (LN) memory CD4 T cells represent major HIV and simian immunodeficiency virus (SIV) tissue reservoirs, the study of the role of dendritic cells (DCs) in HIV persistence has long been limited to the blood due to difficulties to access lymphoid tissue samples. In this study, we show that LN migratory and resident DC subpopulations harbor distinct phenotypic and transcriptomic profiles. Interestingly, both LN DC subpopulations contain HIV intact provirus and inducible replication-competent HIV despite the expression of the antiviral restriction factor SAMHD1. Notably, LN DC subpopulations isolated from HIV-infected individuals treated for up to 14 years are transcriptionally silent but harbor replication-competent virus that can be induced upon TLR7/8 stimulation. Taken together, these results uncover a potential important contribution of LN DCs to HIV infection in the presence of ART.

New Dominant-Negative IL6ST Variants Expand the Immunological and Clinical Spectrum of GP130-Dependent Hyper-IgE Syndrome.

Patients with autosomal dominant (AD) hyper-IgE syndrome (HIES) suffer from a constellation of manifestations including recurrent bacterial and fungal infections, severe atopy, and skeletal abnormalities. This condition is typically caused by monoallelic dominant-negative (DN) STAT3 variants. In 2020, we described 12 patients from eight kindreds with DN IL6ST variants resulting in a new form of AD HIES. These variants encoded truncated GP130 receptors, with intact extracellular and transmembrane domains, but lacking the intracellular recycling motif and the four STAT3-binding residues, resulting in an inability to recycle and activate STAT3. We report here two new DN variants of IL6ST in three unrelated families with HIES-AD. The biochemical and clinical impacts of these variants are different from those of the previously reported variants. The p.(Ser731Valfs*8) variant, identified in seven patients from two families, lacks the recycling motif and all the STAT3-binding residues, but its levels on the cell surface are only slightly increased and it underlies mild biological phenotypes with variable clinical expressivity. The p.(Arg768*) variant, identified in a single patient, lacks the recycling motif and the three most distal STAT3-binding residues. This variant accumulates at the cell surface and underlies severe biological and clinical phenotypes. The p.(Ser731Valfs*8) variant shows that a DN GP130 expressed at near normal levels on the cell surface can underlie heterogeneous clinical presentations, ranging from mild to severe. The p.(Arg768*) variant demonstrates that a truncated GP130 protein retaining one STAT3-binding residue can underlie severe HIES.

Real-life drug retention rate and safety of rituximab when treating rheumatic diseases: a single-centre Swiss retrospective cohort study.

BACKGROUND: In Switzerland, rituximab (RTX) is licenced for the treatment of rheumatoid arthritis (RA) and ANCA-associated vasculitis (AAV) but is frequently used off-label to treat other auto-immune diseases (AID), especially connective tissue diseases (CTD). We aimed to characterise the use of RTX in AID in a real-life Swiss setting and compare RTX retention rates and safety outcomes between patients treated for RA, CTD and AAV. METHODS: A retrospective cohort study of patients who started RTX in the Rheumatology Department for RA or AID. The RTX retention rate was analysed using Kaplan-Meier survival curves. Occurrences of serious adverse events (SAE), low IgG levels and anti-drug antibodies (ADA) were reported. RESULTS: Two hundred three patients were treated with RTX: 51.7% had RA, 29.6% CTD, 9.9% vasculitis and 8.9% other AIDs. The total observation time was 665 patient-years. RTX retention probability at 2 years (95%CI) was similar for RA and CTD 0.65 (0.55 to 0.73), 0.60 (0.47 to 0.72) and lower for vasculitis 0.25 (0.09 to 0.45). Survival curves for RTX retention matched closely (p = 0.97) between RA and CTD patients but were lower for patients with vasculitis due to a higher percentage of induced remission. Patients with vasculitis (95%) and CTD (75%) had a higher rate of concomitant glucocorticoid use than RA (60%). Moderate to severe hypogammaglobulinaemia was observed more frequently in patients with vasculitis (35%) than with RA (13%) or CTD (9%) and was associated with an increased risk of presenting a first infectious SAE (HR 2.01, 95% CI 1.04 to 3.91). The incidence rate of SAE was 23.3 SAE/100 patient-years (36% were infectious). When searched, ADAs were observed in 18% of the patients and were detected in 63% of infusions-related SAE. 10 patients died during RTX treatment and up to 12 months after the last RTX infusion, 50% from infection. CONCLUSION: RTX retention rates are similar for patients with RA and CTD but lower for those with vasculitis due to more frequent remission. Patients treated with RTX for vasculitis present more SAE and infectious SAE than patients with RA and CTD, potentially due to a higher use of concomitant glucocorticoids and the occurrence of hypogammaglobulinaemia.

Frequency matters: comparison of drug resistance mutation detection by Sanger and next-generation sequencing in HIV-1.

BACKGROUND: Next-generation sequencing (NGS) is gradually replacing Sanger sequencing (SS) as the primary method for HIV genotypic resistance testing. However, there are limited systematic data on comparability of these methods in a clinical setting for the presence of low-abundance drug resistance mutations (DRMs) and their dependency on the variant-calling thresholds. METHODS: To compare the HIV-DRMs detected by SS and NGS, we included participants enrolled in the Swiss HIV Cohort Study (SHCS) with SS and NGS sequences available with sample collection dates ≤7 days apart. We tested for the presence of HIV-DRMs and compared the agreement between SS and NGS at different variant-calling thresholds. RESULTS: We included 594 pairs of SS and NGS from 527 SHCS participants. Males accounted for 80.5% of the participants, 76.3% were ART naive at sample collection and 78.1% of the sequences were subtype B. Overall, we observed a good agreement (Cohen's kappa >0.80) for HIV-DRMs for variant-calling thresholds ≥5%. We observed an increase in low-abundance HIV-DRMs detected at lower thresholds [28/417 (6.7%) at 10%-25% to 293/812 (36.1%) at 1%-2% threshold]. However, such low-abundance HIV-DRMs were overrepresented in ART-naive participants and were in most cases not detected in previously sampled sequences suggesting high sequencing error for thresholds <3%. CONCLUSIONS: We found high concordance between SS and NGS but also a substantial number of low-abundance HIV-DRMs detected only by NGS at lower variant-calling thresholds. Our findings suggest that a substantial fraction of the low-abundance HIV-DRMs detected at thresholds <3% may represent sequencing errors and hence should not be overinterpreted in clinical practice.

Erratum: CD177, a specific marker of neutrophil activation, is associated with coronavirus disease 2019 severity and death.

[This corrects the article DOI: 10.1016/j.isci.2021.102711.].

Quantifying and Predicting Ongoing Human Immunodeficiency Virus Type 1 Transmission Dynamics in Switzerland Using a Distance-Based Clustering Approach.

BACKGROUND: Despite effective prevention approaches, ongoing human immunodeficiency virus 1 (HIV-1) transmission remains a public health concern indicating a need for identifying its drivers. METHODS: We combined a network-based clustering method using evolutionary distances between viral sequences with statistical learning approaches to investigate the dynamics of HIV transmission in the Swiss HIV Cohort Study and to predict the drivers of ongoing transmission. RESULTS: We found that only a minority of clusters and patients acquired links to new infections between 2007 and 2020. While the growth of clusters and the probability of individual patients acquiring new links in the transmission network was associated with epidemiological, behavioral, and virological predictors, the strength of these associations decreased substantially when adjusting for network characteristics. Thus, these network characteristics can capture major heterogeneities beyond classical epidemiological parameters. When modeling the probability of a newly diagnosed patient being linked with future infections, we found that the best predictive performance (median area under the curve receiver operating characteristic AUCROC = 0.77) was achieved by models including characteristics of the network as predictors and that models excluding them performed substantially worse (median AUCROC = 0.54). CONCLUSIONS: These results highlight the utility of molecular epidemiology-based network approaches for analyzing and predicting ongoing HIV transmission dynamics. This approach may serve for real-time prospective assessment of HIV transmission.

SARS-CoV-2 neutralizing antibody response in vaccinated and non-vaccinated hospital healthcare workers with or without history of infection.

Between March 2021 and February 2022, SARS-CoV-2 neutralizing antibodies dynamics was investigated in a prospective observational study in 903 healthcare workers of a hospital in Switzerland. A surrogate neutralization assay measuring the competitive inhibition of the angiotensin converting enzyme 2 (ACE2) binding to the spike protein (S) of the SARS-CoV-2 wild type virus and to five variants of concern (Alpha, Beta, Gamma, Delta, Omicron) was used. We observed a broad distribution of neutralization activity among participants and substantial differences in neutralizing titers against variants. Participants were grouped based on combinations of vaccination status (1, 2 or 3 doses) and/or prior or subsequent SARS-CoV-2 infection/reinfection. Triple vaccination resulted in the highest neutralization response, as did double vaccination with prior or subsequent infection. Double vaccination without infection showed an intermediate neutralization response while SARS-CoV-2 infection in non-vaccinated participants resulted in poor neutralization response. After triple vaccination or double vaccination plus infection, additional vaccination and/or reinfection had no impact on neutralizing antibody titers over the observed period. These results strongly support the booster dose strategy, while additional booster doses within short time intervals might not improve immunization. However, dynamics of neutralizing antibodies titers needs to be monitored individually, over time and include newly emerging variants.

CXCL12 and CXCL13 Cytokine Serum Levels Are Associated with the Magnitude and the Quality of SARS-CoV-2 Humoral Responses.

A better understanding of the immunological markers associated with long-lasting immune responses to SARS-CoV-2 infection is of paramount importance. In the present study, we characterized SARS-CoV-2-specific humoral responses in hospitalized (ICU and non-ICU) and non-hospitalized individuals at six months post-onset of symptoms (POS) (N = 95). We showed that the proportion of individuals with detectable anti-SARS-CoV-2 IgG or neutralizing (NAb) responses and the titers of antibodies were significantly reduced in non-hospitalized individuals, compared to ICU- or non-ICU-hospitalized individuals at 6 months POS. Interestingly, SARS-CoV-2-specific memory B cells persist at 6 months POS in both ICU and non-ICU patients and were enriched in cells harboring an activated and/or exhausted phenotype. The frequency/phenotype of SARS-CoV-2-specific memory B cells and the magnitude of IgG or NAb responses at 6 months POS correlated with the serum immune signature detected at patient admission. In particular, the serum levels of CXCL13, IL-1RA, and G-CSF directly correlated with the frequency of Spike-specific B cells and the magnitude of Spike-specific IgG or NAb, while the serum levels of CXCL12 showed an antagonizing effect. Our results indicate that the balance between CXCL12 and CXCL13 is an early marker associated with the magnitude and the quality of the SARS-CoV-2 humoral memory.

Host Molecule Incorporation into HIV Virions, Potential Influences in HIV Pathogenesis.

During the last phase of HIV viral production, nascent HIV virions acquire a fraction of the cellular lipid membrane to create the external lipid envelope, a process by which cellular proteins present on the surface of the infected cell can be incorporated along with Env trimers. Interestingly, several studies indicated that these incorporated host molecules could conserve their biological activity and consequently contribute to HIV pathogenesis either by enhancing the infectivity of HIV virions, their tissue tropism or by affecting immune cell functions. The following review will describe the main approaches used to characterize membrane bound host molecule incorporation into HIV virions, the proposed mechanisms involved, and the role of a non-exhaustive list of incorporated molecules.

The deficiency in Th2-like Tfh cells affects the maturation and quality of HIV-specific B cell response in viremic infection.

Optimal T follicular helper (Tfh) cells function is important to promote the development of germinal centers and maturation of high affinity antigen-specific B cells. We have found that the expression of CXCR3 defines distinct Tfh subsets: CXCR3+ Th1-like Tfh cells mainly producing single IFN-γ and dual IL-21/IFN-γ and CXCR3- Th2-like Tfh cells mainly producing single IL-4 and dual IL-21/IL-4 cytokines. CXCR3- Th2-like Tfhs are significantly reduced during ongoing HIV replication. While the percentage of Th2-like Tfh cells correlates with that of total and cycling HIV-specific B cells, the percentage of CXCR3+ Th1-like Tfhs correlates with HIV-specific B cells expressing T-bet and CXCR3. Of note, only IL-4 and IL-21 cytokines boosted efficient maturation of HIV-specific B cells while IFN-γ induced expression of T-bet and CXCR3 in B cells. Interestingly, total and HIV-specific CXCR3+ B cells showed lower rate of somatic hypermutation, as compared to CXCR3- B cells. Therefore, the imbalance in Th2/Th1-like Tfhs affects B cell responses in viremic HIV infection.

Magnitude and associated factors of latent tuberculosis infection due to Mycobacterium tuberculosis complex among high-risk groups in urban Bobo-Dioulasso, Burkina Faso.

Objectives: To determine the prevalence and risk factors for latent tuberculosis infection (LTBI) among three high-risk groups - household contacts of TB index cases, healthcare workers and slaughterhouse workers - in Bobo-Dioulasso, Burkina Faso. Methods: Participants were recruited to this cross-sectional study from March to July 2020 after giving informed consent. Sociodemographic, clinical and biological data were collected using a structured questionnaire. The QuantiFERON-TB Gold Plus test (QFT-Plus) and the tuberculin skin test (TST) were used for detection of LTBI. Bivariate and multivariate logistic regression analyses were performed to identify risk factors for LTBI. Results: The prevalence of LTBI among 101 participants (age range 15-68 years) was 67.33% [95% confidence interval (CI) 57.27-76.33] and 84.16% (95% CI 75.55-90.66) based on QFT-Plus and TST results, respectively. Compared with healthcare workers and household contacts of TB index cases, the prevalence of LTBI among slaughterhouse workers was significantly higher for both QTF-Plus (96.8%; P<0.001) and TST (100%; P=0.003). Working in a slaughterhouse [adjusted odds ratio (AOR) 1.095, 95% CI 1.00-2.036], smoking (AOR 4.214, 95% CI 1.051-16.899), ≥15 years of exposure (AOR 5.617, 95% CI 1.202-32.198), having an animal at home (AOR 2.735, 95% CI 1.102-6.789) and protozoal infection (AOR 2.591, 95% CI 1.034-6.491) were significantly associated with LTBI on the QFT-Plus assay. Conclusion: The prevalence of LTBI was high in all three groups, particularly slaughterhouse workers. The risk factors identified could form the basis of targeted intervention.

Elite and posttreatment controllers, two facets of HIV control.

PURPOSE OF REVIEW: The quest for HIV-1 cure could take advantage of the study of rare individuals that control viral replication spontaneously (elite controllers) or after an initial course of antiretroviral therapy (posttreatment controllers, PTCs). In this review, we will compare back-to-back the immunological and virological features underlying viral suppression in elite controllers and PTCs, and explore their possible contributions to the HIV-1 cure research. RECENT FINDINGS: HIV-1 control in elite controllers shows hallmarks of an effective antiviral response, favored by genetic background and possibly associated to residual immune activation. The immune pressure in elite controllers might select against actively transcribing intact proviruses, allowing the persistence of a small and poorly inducible reservoir. Evidence on PTCs is less abundant but preliminary data suggest that antiviral immune responses may be less pronounced. Therefore, these patients may rely on distinct mechanisms, not completely elucidated to date, suppressing HIV-1 transcription and replication. SUMMARY: PTCs and elite controllers may control HIV replication using distinct pathways, the elucidation of which may contribute to design future interventional strategies aiming to achieve a functional cure.

Heterogenous humoral and cellular immune responses with distinct trajectories post-SARS-CoV-2 infection in a population-based cohort.

To better understand the development of SARS-CoV-2-specific immunity over time, a detailed evaluation of humoral and cellular responses is required. Here, we characterize anti-Spike (S) IgA and IgG in a representative population-based cohort of 431 SARS-CoV-2-infected individuals up to 217 days after diagnosis, demonstrating that 85% develop and maintain anti-S responses. In a subsample of 64 participants, we further assess anti-Nucleocapsid (N) IgG, neutralizing antibody activity, and T cell responses to Membrane (M), N, and S proteins. In contrast to S-specific antibody responses, anti-N IgG levels decline substantially over time and neutralizing activity toward Delta and Omicron variants is low to non-existent within just weeks of Wildtype SARS-CoV-2 infection. Virus-specific T cells are detectable in most participants, albeit more variable than antibody responses. Cluster analyses of the co-evolution of antibody and T cell responses within individuals identify five distinct trajectories characterized by specific immune patterns and clinical factors. These findings demonstrate the relevant heterogeneity in humoral and cellular immunity to SARS-CoV-2 while also identifying consistent patterns where antibody and T cell responses may work in a compensatory manner to provide protection.