SARS-CoV-2 BA.2.86 enters lung cells and evades neutralizing antibodies with high efficiency.

BA.2.86, a recently identified descendant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2 sublineage, contains ∼35 mutations in the spike (S) protein and spreads in multiple countries. Here, we investigated whether the virus exhibits altered biological traits, focusing on S protein-driven viral entry. Employing pseudotyped particles, we show that BA.2.86, unlike other Omicron sublineages, enters Calu-3 lung cells with high efficiency and in a serine- but not cysteine-protease-dependent manner. Robust lung cell infection was confirmed with authentic BA.2.86, but the virus exhibited low specific infectivity. Further, BA.2.86 was highly resistant against all therapeutic antibodies tested, efficiently evading neutralization by antibodies induced by non-adapted vaccines. In contrast, BA.2.86 and the currently circulating EG.5.1 sublineage were appreciably neutralized by antibodies induced by the XBB.1.5-adapted vaccine. Collectively, BA.2.86 has regained a trait characteristic of early SARS-CoV-2 lineages, robust lung cell entry, and evades neutralizing antibodies. However, BA.2.86 exhibits low specific infectivity, which might limit transmissibility.

The Omicron variant is highly resistant against antibody-mediated neutralization: Implications for control of the COVID-19 pandemic.

The rapid spread of the SARS-CoV-2 Omicron variant suggests that the virus might become globally dominant. Further, the high number of mutations in the viral spike protein raised concerns that the virus might evade antibodies induced by infection or vaccination. Here, we report that the Omicron spike was resistant against most therapeutic antibodies but remained susceptible to inhibition by sotrovimab. Similarly, the Omicron spike evaded neutralization by antibodies from convalescent patients or individuals vaccinated with the BioNTech-Pfizer vaccine (BNT162b2) with 12- to 44-fold higher efficiency than the spike of the Delta variant. Neutralization of the Omicron spike by antibodies induced upon heterologous ChAdOx1 (Astra Zeneca-Oxford)/BNT162b2 vaccination or vaccination with three doses of BNT162b2 was more efficient, but the Omicron spike still evaded neutralization more efficiently than the Delta spike. These findings indicate that most therapeutic antibodies will be ineffective against the Omicron variant and that double immunization with BNT162b2 might not adequately protect against severe disease induced by this variant.

COVID-19 immune signatures reveal stable antiviral T cell function despite declining humoral responses.

Cellular and humoral immunity to SARS-CoV-2 is critical to control primary infection and correlates with severity of disease. The role of SARS-CoV-2-specific T cell immunity, its relationship to antibodies, and pre-existing immunity against endemic coronaviruses (huCoV), which has been hypothesized to be protective, were investigated in 82 healthy donors (HDs), 204 recovered (RCs), and 92 active COVID-19 patients (ACs). ACs had high amounts of anti-SARS-CoV-2 nucleocapsid and spike IgG but lymphopenia and overall reduced antiviral T cell responses due to the inflammatory milieu, expression of inhibitory molecules (PD-1, Tim-3) as well as effector caspase-3, -7, and -8 activity in T cells. SARS-CoV-2-specific T cell immunity conferred by polyfunctional, mainly interferon-γ-secreting CD4+ T cells remained stable throughout convalescence, whereas humoral responses declined. Immune responses toward huCoV in RCs with mild disease and strong cellular SARS-CoV-2 T cell reactivity imply a protective role of pre-existing immunity against huCoV.

Status of HIV and comorbidities in refugees with HIV from Ukraine.

PURPOSE: To describe the clinical characteristics of refugees with HIV from Ukraine that seek continuation of medical care in Germany. METHODS: Fourty-six refugees with HIV that had left Ukraine between 24 February and 30 December 2022 were examined. Information on patients' history was obtained using a standardized questionnaire for clinical care. Interviews were conducted in Russian during their first clinical presentation. RESULTS: Fourty-six persons (41 females and 5 males) were included and their mean age was 39.6 (±8.4) years. The mean time since HIV diagnosis was 8.0 (median, IQR 7.15) years and 70.3% of participants currently received tenfofovir-DF, lamividine and dolutegravir. Most refugees had an undetectable HIV viral load and their current mean CD4 T cell count was 702 (SD ± 289) per µL. Serology revealed previous hepatitis B infection in 50.4% without evidence for replication, with undetectable anti-hepatitis B surface antigen in the remaining refugees. Antibodies against hepatitis C were present in 23 refugees (50%), but only 10 patients had been diagnosed with hepatitis C previously. Five refugees had undergone successful antiviral treatment for hepatitis C. Detectable HCV-RNA was evident in nine patients (19.6%). Sixteen (38.6%) refugees had a positive tuberculosis (TB) interferon gamma release assay, and four were on TB treatment for previously diagnosed infection. One had been diagnosed with multidrug-resistant (MDR) TB, two with pre-extensively drug-resistant (pre-XDR) TB and two with XDR TB and were treated with combinations of second-line and novel agents according to WHO guidelines. CONCLUSIONS: Based on this preliminary analysis of a not fully representative cohort, refugees with HIV from Ukraine were young, mostly healthy females highly adherent to antiretroviral therapy. The rate of transmittable co-infections urges early diagnostic evaluation and treatment.

Limited Weight Impact After Switching From Boosted Protease Inhibitors to Dolutegravir in Persons With Human Immunodeficiency Virus With High Cardiovascular Risk: A Post Hoc Analysis of the 96-Week NEAT-022 Randomized Trial.

BACKGROUND: In the NEAT022 trial, virologically suppressed persons with human immunodeficiency virus (HIV) at high cardiovascular risk switching from protease inhibitors to dolutegravir either immediately (DTG-I) or after 48 weeks (DTG-D) showed noninferior virological suppression and significant lipid and cardiovascular disease risk reductions on switching to dolutegravir relative to continuing protease inhibitors. METHODS: In post hoc analysis, major endpoints were 48-week and 96-week weight and body mass index (BMI) changes. Factors associated with weight/BMI changes within the first 48 weeks of DTG exposure, proportion of participants by category of percentage weight change, proportions of BMI categories over time, and impact on metabolic outcomes were also assessed. RESULTS: Between May 2014 and November 2015, 204 (DTG-I) and 208 (DTG-D) participants were included. Weight significantly increased (mean, +0.810 kg DTG-I arm, and +0.979 kg DTG-D arm) in the first 48 weeks postswitch, but remained stable from 48 to 96 weeks in DTG-I arm. Switching from darunavir, White race, total to high-density lipoprotein cholesterol ratio <3.7, and normal/underweight BMI were independently associated with higher weight/BMI gains. The proportion of participants with ≥5% weight change increased similarly in both arms over time. The proportions of BMI categories, use of lipid-lowering drugs, diabetes and/or use of antidiabetic agents, and hypertension and/or use of antihypertensive agents did not change within or between arms at 48 and 96 weeks. CONCLUSIONS: Switching from protease inhibitors to dolutegravir in persons with HIV with high cardiovascular risk led to modest weight gain limited to the first 48 weeks, which involved preferentially normal-weight or underweight persons and was not associated with negative metabolic outcomes. CLINICAL TRIALS REGISTRATION: NCT02098837 and EudraCT 2013-003704-39.

Incidence of Hypertension and Blood Pressure Changes in Persons With Human Immunodeficiency Virus at High Risk for Cardiovascular Disease Switching From Boosted Protease Inhibitors to Dolutegravir: A Post-hoc Analysis of the 96-week Randomised NEAT-022 Trial.

BACKGROUND: Integrase inhibitors have been recently linked to a higher risk for hypertension. In NEAT022 randomized trial, virologically suppressed persons with human immunodeficiency virus (HIV, PWH) with high cardiovascular risk switched from protease inhibitors to dolutegravir either immediately (DTG-I) or after 48 weeks (DTG-D). METHODS: Primary endpoint was incident hypertension at 48 weeks. Secondary endpoints were changes in systolic (SBP) and diastolic (DBP) blood pressure; adverse events and discontinuations associated with high blood pressure; and factors associated with incident hypertension. RESULTS: At baseline, 191 (46.4%) participants had hypertension and 24 persons without hypertension were receiving antihypertensive medications for other reasons. In the 197 PWH (n = 98, DTG-I arm; n = 99, DTG-D arm) without hypertension or antihypertensive agents at baseline, incidence rates per 100 person-years were 40.3 and 36.3 (DTG-I) and 34.7 and 52.0 (DTG-D) at 48 (P = .5755) and 96 (P = .2347) weeks. SBP or DBP changes did not differed between arms. DBP (mean, 95% confidence interval) significantly increased in both DTG-I (+2.78 mmHg [1.07-4.50], P = .0016) and DTG-D (+2.29 mmHg [0.35-4.23], P = .0211) arms in the first 48 weeks of exposure to dolutegravir. Four (3 under dolutegravir, 1 under protease inhibitors) participants discontinued study drugs due to adverse events associated with high blood pressure. Classical factors, but not treatment arm, were independently associated with incident hypertension. CONCLUSIONS: PWH at high risk for cardiovascular disease showed high rates of hypertension at baseline and after 96 weeks. Switching to dolutegravir did not negatively impact on the incidence of hypertension or blood pressure changes relative to continuing protease inhibitors.

Amino acids, post-translational modifications, nitric oxide, and oxidative stress in serum and urine of long COVID and ex COVID human subjects.

In this study, we investigated the status of amino acids, their post-translational modifications (PTM), major nitric oxide (NO) metabolites and of malondialdehyde (MDA) as a biomarker of oxidative stress in serum and urine samples of long COVID (LoCo, n = 124) and ex COVID (ExCo, n = 24) human subjects collected in 2022. Amino acids and metabolites were measured by gas chromatography-mass spectrometry (GC-MS) methods using stable-isotope labelled analogs as internal standards. There were no differences with respect to circulating and excretory arginine and asymmetric dimethylarginine (ADMA). LoCo participants excreted higher amounts of guanidino acetate than ExCo participants (17.8 ± 10.4 µM/mM vs. 12.6 ± 8.86 µM/mM, P = 0.005). By contrast, LoCo participants excreted lower amounts of the advanced glycation end-product (AGE) NG-carboxyethylarginine (CEA) than ExCo participants did (0.675 ± 0.781 µM/mM vs. 1.16 ± 2.04 µM/mM, P = 0.0326). The serum concentrations of MDA did not differ between the groups, indicating no elevated oxidative stress in LoCo or ExCo. The serum concentration of nitrite was lower in LoCo compared to ExCo (1.96 ± 0.92 µM vs. 2.56 ± 1.08 µM; AUC, 0.718), suggesting altered NO synthesis in the endothelium. The serum concentration of nitrite correlated inversely with the symptom anxiety (r = - 0.293, P = 0.0003). The creatinine-corrected urinary excretion of Lys and its metabolite L-5-hydroxy-Lys correlated positively with COVID toes (r = 0.306, P = 0.00027) and sore throat (r = 0.302, P = 0.0003). Our results suggest that amino acid metabolism, PTM and oxidative stress are not severely affected in long COVID. LoCo participants may have a lower circulating NO reservoir than ExCo.

Diminishing Immune Responses against Variants of Concern in Dialysis Patients 4 Months after SARS-CoV-2 mRNA Vaccination.

Patients undergoing chronic hemodialysis were among the first to receive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinations because of their increased risk for severe coronavirus disease and high case-fatality rates. By using a previously reported cohort from Germany of at-risk hemodialysis patients and healthy donors, where antibody responses were examined 3 weeks after the second vaccination, we assessed systemic cellular and humoral immune responses in serum and saliva 4 months after vaccination with the Pfizer-BioNTech BNT162b2 vaccine using an interferon-γ release assay and multiplex-based IgG measurements. We further compared neutralization capacity of vaccination-induced IgG against 4 SARS-CoV-2 variants of concern (Alpha, Beta, Gamma, and Delta) by angiotensin-converting enzyme 2 receptor-binding domain competition assay. Sixteen weeks after second vaccination, compared with 3 weeks after, cellular and humoral responses against the original SARS-CoV-2 isolate and variants of concern were substantially reduced. Some dialysis patients even had no detectable B- or T-cell responses.

Humoral immune response following prime and boost BNT162b2 vaccination in people living with HIV on antiretroviral therapy.

OBJECTIVES: People living with HIV (PLWH) with low CD4 T-cell counts may be at a higher risk for severe coronavirus disease 2019 (COVID-19) outcomes and in need of efficient vaccination. The World Health Organization (WHO) now recommends prioritizing PLHIV for COVID-19 vaccination. Data on immune responses after messenger RNA (mRNA) vaccination in PLHIV in relation to CD4 counts are scarce. We aimed at assessing the humoral immune response in PLHIV after mRNA vaccination against COVID-19. METHODS: We examined a cohort of PLHIV after prime (n = 88) and boost (n = 52) vaccination with BNT162b2. We assessed levels of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein-specific immunoglobulin G (IgG)/IgA and circulating neutralizing antibodies in plasma and correlated results to the cellular immune status. BNT162b2-vaccinated health care workers served as controls. RESULTS: All PLWH had a viral load of ≤ 200 HIV-1 RNA copies/mL and 96.5% had a viral load of < 50 copies/mL. Anti-S IgG and neutralizing antibody responses after BNT162b2 priming were significantly lower in PLHIV having a CD4:CD8 T-cell ratio of < 0.5. However, we observed robust humoral immunity in the majority of PLWH receiving antiretroviral therapy (ART) irrespective of CD4 T-cell nadir, current CD4 count or CD4:CD8 ratio after full BNT162b2 vaccination. Nevertheless, HIV-negative controls produced significantly higher mean anti-S IgG concentrations with less variability. CONCLUSIONS: The majority of PLWH mounted robust responses after complete BNT162b2 vaccination but overall amounts of antibodies directed against the SARS-CoV-2 receptor-binding domain were variable. The impact on clinical efficacy remains unclear.

Major revision version 11.0 of the European AIDS Clinical Society Guidelines 2021.

BACKGROUND: The European AIDS Clinical Society (EACS) Guidelines were revised in 2021 for the 17th time with updates on all aspects of HIV care. KEY POINTS OF THE GUIDELINES UPDATE: Version 11.0 of the Guidelines recommend six first-line treatment options for antiretroviral treatment (ART)-naïve adults: tenofovir-based backbone plus an unboosted integrase inhibitor or plus doravirine; abacavir/lamivudine plus dolutegravir; or dual therapy with lamivudine or emtricitabine plus dolutegravir. Recommendations on preferred and alternative first-line combinations from birth to adolescence were included in the new paediatric section made with Penta. Long-acting cabotegravir plus rilpivirine was included as a switch option and, along with fostemsavir, was added to all drug-drug interaction (DDI) tables. Four new DDI tables for anti-tuberculosis drugs, anxiolytics, hormone replacement therapy and COVID-19 therapies were introduced, as well as guidance on screening and management of anxiety disorders, transgender health, sexual health for women and menopause. The sections on frailty, obesity and cancer were expanded, and recommendations for the management of people with diabetes and cardiovascular disease risk were revised extensively. Treatment of recently acquired hepatitis C is recommended with ongoing risk behaviour to reduce transmission. Bulevirtide was included as a treatment option for the hepatitis Delta virus. Drug-resistant tuberculosis guidance was adjusted in accordance with the 2020 World Health Organization recommendations. Finally, there is new guidance on COVID-19 management with a focus on continuance of HIV care. CONCLUSIONS: In 2021, the EACS Guidelines were updated extensively and broadened to include new sections. The recommendations are available as a free app, in interactive web format and as an online pdf.

Development of the HIV360 international core set of outcome measures for adults living with HIV: A consensus process.

OBJECTIVES: HIV outcomes centre primarily around clinical markers with limited focus on patient-reported outcomes. With a global trend towards capturing the outcomes that matter most to patients, there is agreement that standardizing the definition of value in HIV care is key to their incorporation. This study aims to address the lack of routine, standardized data in HIV care. METHODS: An international working group (WG) of 37 experts and patients, and a steering group (SG) of 18 experts were convened from 14 countries. The project team (PT) identified outcomes by conducting a literature review, screening 1979 articles and reviewing the full texts of 547 of these articles. Semi-structured interviews and advisory groups were performed with the WG, SG and people living with HIV to add to the list of potentially relevant outcomes. The WG voted via a modified Delphi process - informed by six Zoom calls - to establish a core set of outcomes for use in clinical practice. RESULTS: From 156 identified outcomes, consensus was reached to include three patient-reported outcomes, four clinician-reported measures and one administratively reported outcome; standardized measures were included. The WG also reached agreement to measure 22 risk-adjustment variables. This outcome set can be applied to any person living with HIV aged > 18 years. CONCLUSIONS: Adoption of the HIV360 outcome set will enable healthcare providers to record, compare and integrate standardized metrics across treatment sites to drive quality improvement in HIV care.

Immunogenicity of COVID-19 Vaccination in Melanoma Patients under Immune Checkpoint Blockade.

BACKGROUND: Immunogenicity of SARS-CoV-2 vaccines is modestly impaired in cancer patients due to a generally weakened immune system. Immune checkpoint inhibitors (ICI) are expected to enhance immune response. This has already been described to be the case in influenza vaccines, and first data about COVID-19 vaccines show a trend in this direction. AIM: We aimed to investigate the immune response of patients with melanoma under ICI therapy after COVID-19 vaccination. PATIENTS AND METHODS: In the Skin Cancer Center Hanover (Germany), we recruited 60 patients with advanced melanoma who either received ICI therapy during or before the vaccination period. Serological blood analysis was performed using quantitative ELISA for Anti-SARS-CoV-2 spike protein 1 IgG antibodies. RESULTS: We did not observe an enhanced humoral immune response in patients under active or past ICI therapy after COVID-19 vaccination. Nevertheless, there is a tendency of higher antibody levels when ICI therapy was received within the last 6 months before vaccination. Subgroup analysis revealed that patients in our study population under ongoing targeted therapy during vaccination period had significantly higher median antibody levels than patients without any active antitumor treatment. CONCLUSION: Melanoma patients under ICI therapy show comparable antibody response after SARS-CoV-2 vaccination to healthy health care professionals. This finding is independent of the timing of ICI therapy.

SARS-CoV-2-specific immune responses in elderly and immunosuppressed participants and patients with hematologic disease or checkpoint inhibition in solid tumors: study protocol of the prospective, observational CoCo immune study.

BACKGROUND: Immunocompromised people (ICP) and elderly individuals (older than 80 years) are at increased risk for severe coronavirus infections. To protect against serious infection with SARS-CoV-2, ICP are taking precautions that may include a reduction of social contacts and participation in activities which they normally enjoy. Furthermore, for these people, there is an uncertainty regarding the effectiveness of the vaccination. The COVID-19 Contact (CoCo) Immune study strives to characterize the immune response to COVID-19 vaccination in immunocompromised, elderly people, and patients with hematological or oncological diseases. The study uses blood-based screenings to monitor the humoral and cellular immune response in these groups after vaccination. Questionnaires and qualitative interviews are used to describe the level of social participation. METHODS: The CoCo Immune Study is a mixed methods prospective, longitudinal, observational study at two large university hospitals in Northern Germany. Starting in March 2021, it monitors anti-SARS-CoV-2 immune responses and collects information on social participation in more than 600 participants, at least 18 years old. Inclusion criteria and subcohorts: Participants with (1) regularly intake of immunosuppressive medication (ICP-cohort) or (2) age ≥ 80 years (80 + -cohort). Additionally, patients with current or former (3) myeloid, (4) lymphatic disease or (5) solid tumor under checkpoint inhibition (3-5: HO-cohort). EXCLUSION CRITERIA: (1) refusal to give informed consent, (2) contraindication to blood testing, (3) inability to declare consent. Participants complete a questionnaire at four different time points: prior to full vaccination, and 1, 6 and 12 months after completed vaccination. In addition, participants draw blood samples themselves or through a local health care provider and send them with their questionnaires per post at the respective time points after vaccination. Patients of the HO cohort dispense additional blood samples at week 3 to 12 and at month 6 to 9 after 2nd vaccination to gain additional knowledge in B and T cell responses. Selected participants are invited to qualitative interviews about social participation. DISCUSSION: This observational study is designed to gain insight into the immune response of people with weakened immune systems and to find out how social participation is affected after COVID-19 vaccination. TRIAL REGISTRATION: This study was registered with German Clinical Trial Registry (registration number: DRKS00023972) on 30th December 2020.

National medical specialty guidelines of HIV indicator conditions in Europe lack adequate HIV testing recommendations: a systematic guideline review.

BackgroundAdequate identification and testing of people at risk for HIV is fundamental for the HIV care continuum. A key strategy to improve timely testing is HIV indicator condition (IC) guided testing.AimTo evaluate the uptake of HIV testing recommendations in HIV IC-specific guidelines in European countries.MethodsBetween 2019 and 2021, European HIV experts reviewed guideline databases to identify all national guidelines of 62 HIV ICs. The proportion of HIV IC guidelines recommending HIV testing was reported, stratified by subgroup (HIV IC, country, eastern/western Europe, achievement of 90-90-90 goals and medical specialty).ResultsOf 30 invited European countries, 15 participated. A total of 791 HIV IC guidelines were identified: median 47 (IQR: 38-68) per country. Association with HIV was reported in 69% (545/791) of the guidelines, and 46% (366/791) recommended HIV testing, while 42% (101/242) of the AIDS-defining conditions recommended HIV testing. HIV testing recommendations were observed more frequently in guidelines in eastern (53%) than western (42%) European countries and in countries yet to achieve the 90-90-90 goals (52%) compared to those that had (38%). The medical specialties internal medicine, neurology/neurosurgery, ophthalmology, pulmonology and gynaecology/obstetrics had an HIV testing recommendation uptake below the 46% average. None of the 62 HIV ICs, countries or medical specialties had 100% accurate testing recommendation coverage in all their available HIV IC guidelines.ConclusionFewer than half the HIV IC guidelines recommended HIV testing. This signals an insufficient adoption of this recommendation in non-HIV specialty guidelines across Europe.

The SARS-CoV-2 Delta-Omicron Recombinant Lineage (XD) Exhibits Immune-Escape Properties Similar to the Omicron (BA.1) Variant.

Recently, a recombinant SARS-CoV-2 lineage, XD, emerged that harbors a spike gene that is largely derived from the Omicron variant BA.1 in the genetic background of the Delta variant. This finding raised concerns that the recombinant virus might exhibit altered biological properties as compared to the parental viruses and might pose an elevated threat to human health. Here, using pseudotyped particles, we show that ACE2 binding and cell tropism of XD mimics that of BA.1. Further, XD and BA.1 displayed comparable sensitivity to neutralization by antibodies induced upon vaccination with BNT162b2/Comirnaty (BNT) or BNT vaccination followed by breakthrough infection. Our findings reveal important biological commonalities between XD and Omicron BA.1 host cell entry and its inhibition by antibodies.

Humoral and Cellular Immune Responses Against Severe Acute Respiratory Syndrome Coronavirus 2 Variants and Human Coronaviruses After Single BNT162b2 Vaccination.

BACKGROUND: Vaccine-induced neutralizing antibodies are key in combating the coronavirus disease 2019 (COVID-19) pandemic. However, delays of boost immunization due to limited availability of vaccines may leave individuals vulnerable to infection and prolonged or severe disease courses. The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC)-B.1.1.7 (United Kingdom), B.1.351 (South Africa), and P.1 (Brazil)-may exacerbate this issue, as the latter two are able to evade control by antibodies. METHODS: We assessed humoral and T-cell responses against SARS-CoV-2 wild-type (WT), VOC, and endemic human coronaviruses (hCoVs) that were induced after single and double vaccination with BNT162b2. RESULTS: Despite readily detectable immunoglobulin G (IgG) against the receptor-binding domain of the SARS-CoV-2 S protein at day 14 after a single vaccination, inhibition of SARS-CoV-2 S-driven host cell entry was weak and particularly low for the B.1.351 variant. Frequencies of SARS-CoV-2 WT and VOC-specific T cells were low in many vaccinees after application of a single dose and influenced by immunity against endemic hCoV. The second vaccination significantly boosted T-cell frequencies reactive for WT and B.1.1.7 and B.1.351 variants. CONCLUSIONS: These results call into question whether neutralizing antibodies significantly contribute to protection against COVID-19 upon single vaccination and suggest that cellular immunity is central for the early defenses against COVID-19.

Perceived versus proven SARS-CoV-2-specific immune responses in health-care professionals.

There have been concerns about high rates of thus far undiagnosed SARS-CoV-2 infections in the health-care system. The COVID-19 Contact (CoCo) Study follows 217 frontline health-care professionals at a university hospital with weekly SARS-CoV-2-specific serology (IgA/IgG). Study participants estimated their personal likelihood of having had a SARS-CoV-2 infection with a mean of 21% [median 15%, interquartile range (IQR) 5-30%]. In contrast, anti-SARS-CoV-2 IgG prevalence was about 1-2% at baseline. Regular anti-SARS-CoV-2 IgG testing of health-care professionals may aid in directing resources for protective measures and care of COVID-19 patients in the long run.

The Loss of HLA-F/KIR3DS1 Ligation Is Mediated by Hemoglobin Peptides.

The human leukocyte antigen (HLA)-Ib molecule, HLA-F, is known as a CD4+ T-cell protein and mediator of HIV progression. While HLA-Ia molecules do not have the chance to select and present viral peptides for immune recognition due to protein downregulation, HLA-F is upregulated. Post HIV infection, HLA-F loses the affinity to its activating receptor KIR3DS1 on NK cells leading to progression of the HIV infection. Several studies aimed to solve the question of the biophysical interface between HLA ligands and their cognate receptors. It became clear that even an invariant HLA molecule can be structurally modified by the variability of the bound peptide. We recently discovered the ability of HLA-F to select and present peptides and the HLA-F allele-specific peptide selection from the proteomic content using soluble HLA (sHLA) technology and a sophisticated MS method. We established recombinant K562 cells that express membrane-bound HLA-F*01:01, 01:03 or 01:04 complexes. While a recombinant soluble form of KIR3DS1 did not bind to the peptide-HLA-F complexes, acid elution of the peptides resulted in the presentation of HLA-F open conformers, and the binding of the soluble KIR3DS1 receptor increased. We used CD4+/HIV- and CD4+/HIV+ cells and performed an MS proteome analysis. We could detect hemoglobin as significantly upregulated in CD4+ T-cells post HIV infection. The expression of cellular hemoglobin in nonerythroid cells has been described, yet HLA-Ib presentation of hemoglobin-derived peptides is novel. Peptide sequence analysis from HLA-F allelic variants featured hemoglobin peptides as dominant and shared. The reciprocal experiment of binding hemoglobin peptide fractions to the HLA-F open conformers resulted in significantly diminished receptor recognition. These results underpin the molecular involvement of HLA-F and its designated peptide ligand in HIV immune escape.

Immunogenic cell death of dendritic cells following modified vaccinia virus Ankara infection enhances CD8+ T cell proliferation.

"Immunogenic cell death" (ICD) is associated with the emission of so-called damage-associated molecular patterns (DAMPs) which trigger the immune response against dead-cell associated antigens. The secretion of the DAMP, adenosine triphosphate (ATP) has been shown to be autophagy-dependent. Here, we demonstrate that Modified Vaccinia virus Ankara (MVA), a highly attenuated strain of vaccinia virus, induces both cell death and autophagy in murine bone marrow-derived dendritic cells (BMDCs), which in turn confer the (cross-)priming of OVA-specific cytotoxic T cells (OT-I cells). Additionally, we show that MVA infection leads to increased extracellular ATP (eATP) as well as intracellular ATP (iATP) levels, with the latter being influenced by the autophagy. Furthermore, we show that the increased eATP supports the proliferation of OT-I cells and inhibition of the P2RX7 receptors results in an abrogation of the proliferation. These data reveal novel mechanisms on how MVA enhances adaptive immunity in vaccine strategies.

Herpes simplex virus 1 interferes with autophagy of murine dendritic cells and impairs their ability to stimulate CD8+ T lymphocytes.

The MHC class I presentation is responsible for the presentation of viral proteins to CD8+ T lymphocytes and mainly depends on the classical antigen processing pathway. Recently, a second pathway involving autophagy has been implicated in this process. Here, we show an increase in the capacity of murine dendritic cells (DCs) to present viral antigens on MHC class I after infection with a mutant herpes simplex virus 1 (HSV-1-Δ34.5), lacking infected cell protein 34.5 (ICP34.5), when compared to its parental HSV-1 strain. The ICP34.5 protein counteracts host cell translational arrest and suppresses macroautophagy, and the lack of this protein resulted in a low viral protein abundance, which was processed and presented in an efficient way. Our study demonstrates an important role of autophagy in processing endogenous viral proteins in HSV-1-infected DCs.