A preprint by Farias et al. shows that the type I interferon response to respiratory syncytial virus infection reduces lung metastasis of breast cancer in a mouse model.

Although not formally defined as a neglected tropical disease, HIV-2 infection attracts remarkably little attention or investment compared with its pandemic relative, HIV-1. Efficacy and safety of three antiretroviral therapy regimens for treatment-naive African adults living with HIV-2 (FIT-2): a pilot, phase 2, non-comparative, open-label, randomised controlled trialThe raltegravir and ritonavir-boosted lopinavir regimens were efficient and safe in adults with HIV-2. Both regimens could be compared in future phase 3 trials. The results of this pilot study suggest a trend towards better virological and immunological efficacy in the raltegravir-based regimen. Full-Text PDF Open Access

A preprint by Ngo et al. reports a new mouse model for the constitutive depletion of pDCs, showing that pDCs are dispensable for antiviral immunity.

We assessed a cohort of people living with human immunodeficiency virus (PLWH) (n = 110) and HIV negative controls (n = 64) after 1, 2 or 3 SARS-CoV-2 vaccine doses. At all timepoints, PLWH had significantly lower neutralizing antibody (nAb) titers than HIV-negative controls. We also observed a delayed development of neutralization in PLWH that was underpinned by a reduced frequency of spike-specific memory B cells (MBCs). Improved neutralization breadth was seen against the Omicron variant (BA.1) after the third vaccine dose in PLWH but lower nAb responses persisted and were associated with global MBC dysfunction. In contrast, SARS-CoV-2 vaccination induced robust T cell responses that cross-recognized variants in PLWH. Strikingly, individuals with low or absent neutralization had detectable functional T cell responses. These PLWH had reduced numbers of circulating T follicular helper cells and an enriched population of CXCR3(+)CD127(+)CD8(+)T cells after two doses of SARS-CoV-2 vaccination.

Interest in MHC-E–restricted CD8+ T cell responses has been aroused by the discovery of their efficacy in controlling simian immunodeficiency virus (SIV) infection in a vaccine model. The development of vaccines and immunotherapies utilizing human MHC-E (HLA-E)–restricted CD8+ T cell response requires an understanding of the pathway(s) of HLA-E transport and antigen presentation, which have not been clearly defined previously. We show here that, unlike classical HLA class I, which rapidly exits the endoplasmic reticulum (ER) after synthesis, HLA-E is largely retained because of a limited supply of high-affinity peptides, with further fine-tuning by its cytoplasmic tail. Once at the cell surface, HLA-E is unstable and is rapidly internalized. The cytoplasmic tail plays a crucial role in facilitating HLA-E internalization, which results in its enrichment in late and recycling endosomes. Our data reveal distinctive transport patterns and delicate regulatory mechanisms of HLA-E, which help to explain its unusual immunological functions.

Cross-institutional journal clubs focused on preprints are a new approach to community-based peer review and allow ERCs to gain experience.

A group of early-career researchers have harnessed cross-institutional journal clubs to assess and review immunology preprints. A group of early-career researchers have harnessed cross-institutional journal clubs to assess and review immunology preprints.

Natural killer (NK) cell subsets with adaptive properties are emerging as regulators of vaccine-induced T and B cell responses and are specialized towards antibody-dependent functions contributing to SARS-CoV-2 control. Although HIV-1 infection is known to affect the NK cell pool, the additional impact of SARS-CoV-2 infection and/or vaccination on NK cell responses in people living with HIV (PLWH) has remained unexplored. Our data show that SARS-CoV-2 infection skews NK cells towards a more differentiated/adaptive CD57 + FcεRIγ − phenotype in PLWH. A similar subset was induced following vaccination in SARS-CoV-2 naïve PLWH in addition to a CD56 bright population with cytotoxic potential. Antibody-dependent NK cell function showed robust and durable responses to Spike up to 148 days post-infection, with responses enriched in adaptive NK cells. NK cell responses were further boosted by the first vaccine dose in SARS-CoV-2 exposed individuals and peaked after the second dose in SARS-CoV-2 naïve PLWH. The presence of adaptive NK cells associated with the magnitude of cellular and humoral responses. These data suggest that features of adaptive NK cells can be effectively engaged to complement and boost vaccine-induced adaptive immunity in potentially more vulnerable groups such as PLWH.

Summary Lentivectors (LVs) induce sustained transgene expression and are attractive vaccine platforms for complex immune scenarios like cancer and persistent infections. This review summarises the literature on lentivectors with potential uses for in vivo immunotherapy, focussing on those targeting the most potent antigen-presenting cells: dendritic cells (DCs). There is a growing interest in myeloid-targeting therapies as, by influencing an early stage in the immune hierarchy, they can orchestrate a more diverse and complex targeted immune response. We dissect the nature of DC-targeting LVs and their induced immune responses to understand the state of the art, identify the knowledge gaps and guide efforts to maximise the generation of potent and effective immune responses. Lentivector-based vaccines provide several advantages over other vaccine platforms, such as directed tropism and limited vector immunogenicity, and have been shown to generate effective and sustained immune responses. Overall, DC-targeting lentivectors stand out as promising tools to be exploited in cancer immunotherapy, and new-generation LVs can further exploit the gained knowledge in the study of naturally occurring lentiviruses for a more directed and adjuvanted response.

Cross-institutional journal clubs focused on preprints are a new approach to community-based peer review and allow ERCs to gain experience.

The academic community has been increasingly using preprints to disseminate their latest research findings quickly and openly. This early and open access of non-peer reviewed research warrants new means from the scientific community to efficiently assess and provide feedback to preprints. Yet, most peer review of scientific studies performed today are still managed by journals, each having their own peer review policy and transparency. However, approaches to uncouple the peer review process from journal publication are emerging. Additionally, formal education of early career researchers (ECRs) in peer reviewing is rarely available, hampering the quality of peer review feedback. Here, we introduce the Preprint Club, a cross-institutional, community-based approach to peer reviewing, founded by ECRs from the University of Oxford, Karolinska Institutet and Icahn School of Medicine at Mount Sinai. Over the past two years and using the collaborative setting of the Preprint Club, we have been discussing, assessing, and providing feedback on recent preprints in the field of immunology. In this article, we provide a blueprint of the Preprint Club basic structure, demonstrate its effectiveness, and detail the lessons we learned on its impact on peer review training and preprint author’s perception.

People living with HIV (PLWH) on suppressive antiretroviral therapy (ART) can have residual immune dysfunction and often display poorer responses to vaccination. We assessed in a cohort of PLWH (n=110) and HIV negative controls (n=64) the humoral and spike-specific B-cell responses following 1, 2 or 3 SARS-CoV-2 vaccine doses. PLWH had significantly lower neutralizing antibody (nAb) titers than HIV-negative controls at all studied timepoints. Moreover, their neutralization breadth was reduced with fewer individuals developing a neutralizing response against the Omicron variant (BA.1) relative to controls. We also observed a delayed development of neutralization in PLWH that was underpinned by a reduced frequency of spike-specific memory B cells (MBCs) and pronounced B cell dysfunction. Improved neutralization breadth was seen after the third vaccine dose in PLWH but lower nAb responses persisted and were associated with global, but not spike-specific, MBC dysfunction. In contrast to the inferior antibody responses, SARS-CoV-2 vaccination induced robust T cell responses that cross-recognized variants in PLWH. Strikingly, a subset of PLWH with low or absent neutralization had detectable functional T cell responses. These individuals had reduced numbers of circulating T follicular helper cells and an enriched population of CXCR3 + CD127 + CD8 + T cells after two doses of SARS-CoV-2 vaccination, which may compensate for sub-optimal serological responses in the event of infection. Therefore, normalisation of B cell homeostasis could improve serological responses to vaccines in PLWH and evaluating T cell immunity could provide a more comprehensive immune status profile in these individuals and others with B cell imbalances.

Although pivotal trials with varying populations and study methods suggest higher efficacy for mRNA than adenoviral Covid-19 vaccines, not many studies have directly compared vaccine effectiveness in the population. Here, we conduct a head-to-head comparison of BNT162b2 versus ChAdOx1 against Covid-19. We analyse 235,181 UK Biobank participants aged 50 years or older and vaccinated with one or two doses of BNT162b2 or ChAdOx1. People are followed from the vaccination date until 18/10/2021. Inverse probability weighting is used to minimise confounding and the Cox models to derive hazard ratio. We find that, compared with one dose of ChAdOx1, vaccination with BNT162b2 is associated with a 28% (95% CI, 12-42) decreased risk of SARS-CoV-2 infection. Also, two doses of BNT162b2 vs ChAdOx1 confers 30% (95% CI, 25-35) and 29% (95% CI, 10-45) lower risks of both infection and hospitalisation during the study period when the Delta variant is dominant. Furthermore, the comparative protection against the infection persists for at least six months among the fully vaccinated, suggesting no differential waning between the two vaccines. These findings can inform evidence-based Covid-19 vaccination campaigns and booster strategies.

preprint by Martinez-Riano et al. evaluates the dynamics of antigen retention by follicular dendritic cells (FDCs) in germinal centres, showing that immune complexes accumulate in the centre of the FDC network.

preprint by Mosallanejad et al. uses a comparative immunology approach to investigate the catalytic domains of cGAS, showing that reactivity to self-DNA is not conserved across mammalian species.

Two preprints describe a role for the RNA editor ADAR1 in recognizing Z-RNA to prevent spontaneous activation of the type I interferon pathway.

There is an urgent need to understand the nature of immune responses against SARS-CoV-2, to inform risk-mitigation strategies for people living with HIV (PLWH). Here we show that the majority of PLWH with ART suppressed HIV viral load, mount a detectable adaptive immune response to SARS-CoV-2. Humoral and SARS-CoV-2-specific T cell responses are comparable between HIV-positive and negative subjects and persist 5-7 months following predominately mild COVID-19 disease. T cell responses against Spike, Membrane and Nucleoprotein are the most prominent, with SARS-CoV-2-specific CD4 T cells outnumbering CD8 T cells. We further show that the overall magnitude of SARS-CoV-2-specific T cell responses relates to the size of the naive CD4 T cell pool and the CD4:CD8 ratio in PLWH. These findings suggest that inadequate immune reconstitution on ART, could hinder immune responses to SARS-CoV-2 with implications for the individual management and vaccine effectiveness in PLWH.

Background: There is an urgent need to understand the nature of immune responses mounted against SARS-CoV-2, in order to better inform riskmitigation and vaccine strategies for people living with HIV (PLWH). Although not all PLWH are considered immunosuppressed, residual cellular immunodeficiency could influence COVID-19 disease severity and the evolution and durability of protective immunity. Information on the breadth, magnitude and longevity of SARS-CoV-2 specific responses in PLWH recovering from COVID-19 disease is currently lacking. In this study, we performed an integrated cross-sectional analysis of different branches of adaptive immunity to SARS-CoV-2 in PLWH and HIV negative donors in the convalescent phase of predominately mild COVID-19 disease. Methods: A total of n=47 HIV positive, controlled on ART, and n=35 HIV negative subjects were recruited at a median of 158 and 146 days post symptom onset respectively. SARS-CoV-2 antibodies against Spike (S1) and Nucleoprotein (N) were measured in serum by a Semiquantitative ELISA. A serum neutralisation assay with pseudotyped SARS-CoV-2 was performed to calculate the 50% inhibitory serum dilution (ID50). SARS-CoV-2 specific memory T cell responses were determined by IFN-γ ELISpot and intracellular cytokine production assays using peptide pools against SARS-CoV-2 structural and accessory proteins (Spike, Membrane, Nucleocapsid, Envelope, and ORF3a,6,7,8). Results: The majority of PLWH had detectable SARS-CoV-2 S-and N-specific antibodies with neutralizing activity at levels comparable to HIV negative subjects (p= 0.5753). Although, the overall magnitude of SARS-CoV-2 specific T cell responses measured by ELISpot was not significantly different between the groups (p=0.4642), this correlated with the size of the naive CD4 T cell pool (r=0.5518, p=0.0143) and the CD4:CD8 ratio in PLWH (r= 0.3820, p=0.037). In both groups, SARS-CoV-2 specific CD4 T cells were more abundant compared to CD8 T cells (HIV-p= 0.002, HIV+ p=0.0019). Both humoral and cellular responses were detected between 5-7 months post infection, providing evidence of medium-term durability of responses irrespective of HIV serostatus. Conclusion: The majority of PLWH mount a functional adaptive immune response to SARS-CoV-2. Incomplete immune reconstitution on ART and persistent alterations in the T cell compartment could, however, impact the development of protective immunity to SARS-CoV-2. These findings have implications for the risk stratification and management of PLWH.

Although pivotal trials with varying populations and study methods suggest higher efficacy for mRNA than adenoviral Covid-19 vaccines, no direct evidence is available. Here, we conducted a head-to-head comparison of BNT162b2 versus ChAdOx1 against Covid-19. We analysed 235,181 UK Biobank participants aged 50 years or older and vaccinated with one or two doses of BNT162b2 or ChAdOx1. People were followed from the vaccination date until 18/10/2021. Inverse probability weighting was used to minimise confounding and the Cox models to derive hazard ratio. We found that, compared with two doses of ChAdOx1, vaccination with BNT162b2 was associated with 30% lower risks of both SARS-CoV-2 infection and related hospitalisation during the period dominated by the delta variant. Also, this comparative effectiveness was consistent across several subgroups and persisted for at least six months, suggesting no differential waning between the two vaccines. Our findings can inform evidence-based Covid-19 vaccination campaigns and booster strategies.

Abstract Destabilization of balanced immune cell numbers and frequencies is a common feature of viral infections. This occurs due to, and further enhances, viral immune evasion and survival. Since the discovery of the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), which manifests in coronavirus disease 2019 (COVID-19), a great number of studies have described the association between this virus and pathologically increased or decreased immune cell counts. In this review, we consider the absolute and relative changes to innate and adaptive immune cell numbers, in COVID-19. In severe disease particularly, neutrophils are increased, which can lead to inflammation and tissue damage. Dysregulation of other granulocytes, basophils and eosinophils represents an unusual COVID-19 phenomenon. Contrastingly, the impact on the different types of monocytes leans more strongly to an altered phenotype, e.g. HLA-DR expression, rather than numerical changes. However, it is the adaptive immune response that bears the most profound impact of SARS-CoV-2 infection. T cell lymphopenia correlates with increased risk of intensive care unit admission and death; therefore, this parameter is particularly important for clinical decision-making. Mild and severe diseases differ in the rate of immune cell counts returning to normal levels post disease. Tracking the recovery trajectories of various immune cell counts may also have implications for long-term COVID-19 monitoring. This review represents a snapshot of our current knowledge, showing that much has been achieved in a short period of time. Alterations in counts of distinct immune cells represent an accessible metric to inform patient care decisions or predict disease outcomes.