An ultrapotent pan-β-coronavirus lineage B (β-CoV-B) neutralizing antibody locks the receptor-binding domain in closed conformation by targeting its conserved epitope

New threats posed by the emerging circulating variants of SARS-CoV-2 highlight the need to find conserved neutralizing epitopes for therapeutic antibodies and efficient vaccine design. Here, we identified a receptor-binding domain (RBD)-binding antibody, XG014, which potently neutralizes β-coronavirus lineage B (β-CoV-B), including SARS-CoV-2, its circulating variants, SARS-CoV and bat SARSr-CoV WIV1. Interestingly, antibody family members competing with XG014 binding show reduced levels of cross-reactivity and induce antibody-dependent SARS-CoV-2 spike (S) protein-mediated cell-cell fusion, suggesting a unique mode of recognition by XG014. Structural analyses reveal that XG014 recognizes a conserved epitope outside the ACE2 binding site and completely locks RBD in the non-functional “down” conformation, while its family member XG005 directly competes with ACE2 binding and position the RBD “up”. Single administration of XG014 is effective in protection against and therapy of SARS-CoV-2 infection in vivo. Our findings suggest the potential to develop XG014 as pan-β-CoV-B therapeutics and the importance of the XG014 conserved antigenic epitope for designing broadly protective vaccines against β-CoV-B and newly emerging SARS-CoV-2 variants of concern.

Intratumoral Combinatorial Administration of CD1c (BDCA-1)+ Myeloid Dendritic Cells Plus Ipilimumab and Avelumab in Combination with Intravenous Low-Dose Nivolumab in Patients with Advanced Solid Tumors: A Phase IB Clinical Trial

Intratumoral (IT) myeloid dendritic cells (myDCs) play a pivotal role in re-licensing antitumor cytotoxic T lymphocytes. IT injection of the IgG1 monoclonal antibodies ipilimumab and avelumab may induce antibody-dependent cellular cytotoxicity, thereby enhancing the release of tumor antigens that can be captured and processed by CD1c (BDCA-1)+ myDCs. Patients with advanced solid tumors after standard care were eligible for IT injections of ≥1 lesion with ipilimumab (10 mg) and avelumab (40 mg) and intravenous (IV) nivolumab (10 mg) on day 1, followed by IT injection of autologous CD1c (BDCA-1)+ myDCs on day 2. IT/IV administration of ipilimumab, avelumab, and nivolumab was repeated bi-weekly. Primary objectives were safety and feasibility. Nine patients were treated with a median of 21 × 106 CD1c (BDCA-1)+ myDCs, and a median of 4 IT/IV administrations of ipilimumab, avelumab, and nivolumab. The treatment was safe with mainly injection-site reactions, but also immune-related pneumonitis (n = 2), colitis (n = 1), and bullous pemphigoid (n = 1). The best response was a durable partial response in a patient with stage IV melanoma who previously progressed on checkpoint inhibitors. Our combinatorial therapeutic approach, including IT injection of CD1c (BDCA-1)+ myDCs, is feasible and safe, and it resulted in encouraging signs of antitumor activity in patients with advanced solid tumors.

Antibodies targeting epitopes on the cell-surface form of NS1 protect against Zika virus infection during pregnancy

There are no licensed therapeutics or vaccines available against Zika virus (ZIKV) to counteract its potential for congenital disease. Antibody-based countermeasures targeting the ZIKV envelope protein have been hampered by concerns for cross-reactive responses that induce antibody-dependent enhancement (ADE) of heterologous flavivirus infection. Nonstructural protein 1 (NS1) is a membrane-associated and secreted glycoprotein that functions in flavivirus replication and immune evasion but is absent from the virion. Although some studies suggest that antibodies against ZIKV NS1 are protective, their activity during congenital infection is unknown. Here we develop mouse and human anti-NS1 monoclonal antibodies that protect against ZIKV in both non-pregnant and pregnant mice. Avidity of antibody binding to cell-surface NS1 along with Fc effector functions engagement correlate with protection in vivo. Protective mAbs map to exposed epitopes in the wing domain and loop face of the β-platform. Anti-NS1 antibodies provide an alternative strategy for protection against congenital ZIKV infection without causing ADE.

Advancements in Research Related to Vaccination Against Avian Coccidiosis

Coccidiosis is a fatal disease of poultry, caused by Eimeria species and considered the most prominent and destructive disease within all protozoal diseases. Chemotherapy is considered the main preventive strategy against coccidiosis. Chemotherapy is partially successful and has many drawbacks as it is practiced after the outbreak of disease, until then coccidiosis causes huge production and health losses. As an alternative, prophylactic measures like vaccination and management betterment are of eminent importance and can help to overcome this disease. Vaccination can induce antibody-mediated immunity, cell-mediated immunity or both. However, ordinary vaccines do not offer enough potential to overcome Eimeria species at its full extent. Different research trials and studies have shown that DNA vaccines can induce both antibody and cell-mediated immunity. Several DNA vaccines have been tested in the last few years with marvelous results but still no vaccine is available commercially. Here we will discuss different types of vaccines against Eimeria, especially in poultry. A comparative analysis along with the recent advancements will reveal the types of vaccines that bear sufficient potential to overcome Eimeria species to its full extent. This review will also describe the fruitful and advanced steps towards the synthesis of molecular vaccines in the future.

TMPRSS2 Protease Inhibitors May Prolong But Heparins Accelerate SARS-CoV-2 Clearance

The 2019 novel SARS-like coronavirus (SARS-CoV-2) entry depends on the host membrane serine protease TMPRSS2, which can be blocked by some clinically-proven drugs. Here we analyzed spatial relevance between glycosylation sequons and antibody epitopes and found that, different from SARS-CoV S, most high-surface-accessible epitopes of SARS-CoV-2 S are blocked by the glycosylation, and the optimal epitope with the highest surface accessibility is covered by the S1 cap. TMPRSS2 inhibitor treatments may prevent unmasking of this epitope and therefore prolong virus clearance and may induce antibody-dependent enhancement. Interestingly, a heparin-binding sequence immediately upstream of the S1/S2 cleavage site has been found in SARS-CoV-2 S but not in SARS-CoV S. Binding of SARS-CoV-2 with heparins may lead to exposure of S686, which then facilitates the S1/S2 cleavage, induces exposure of the optimal epitope, and therefore increases the antibody titres. A combination of heparin and vaccine (or convalescent serum) treatments thus is recommended.

3M-052, a synthetic TLR-7/8 agonist, induces durable HIV-1 envelope–specific plasma cells and humoral immunity in nonhuman primates

A fundamental challenge in vaccinology is learning how to induce durable antibody responses. Live viral vaccines induce antibody responses that last a lifetime, but those induced with subunit vaccines wane rapidly. Studies in mice and humans have established that long-lived plasma cells (LLPCs) in the bone marrow (BM) are critical mediators of durable antibody responses. Here, we present data that adjuvanting an HIV-1 clade C 1086.C–derived gp140 immunogen (Env) with a novel synthetic Toll-like receptor (TLR)–7/8 agonist named 3M-052 formulated in poly(lactic-co-glycolic)acid or PLGA nanoparticles (NPs) or with alum, either alone or in combination with a TLR-4 agonist GLA, induces notably high and persistent (up to ~1 year) frequencies of Env-specific LLPCs in the BM and serum antibody responses in rhesus macaques. Up to 36 and 18% of Env-specific cells among total IgG-secreting BM-resident plasma cells were detected at peak and termination, respectively. In contrast, adjuvanting Env with alum or GLA in NP induced significantly lower (~<100-fold) LLPC and antibody responses. Immune responses induced by 3M-052 were also significantly higher than those induced by a combination of TLR-7/8 (R848) and TLR-4 (MPL) agonists. Adjuvanting Env with 3M-052 also induced robust activation of blood monocytes, strong plasmablast responses in blood, germinal center B cells, T follicular helper (TFH) cells, and persistent Env-specific plasma cells in draining lymph nodes. Overall, these results demonstrate efficacy of 3M-052 in promoting high magnitude and durability of antibody responses via robust stimulation of innate immunity and BM-resident LLPCs.

Immune-Complexome Analysis Identifies Immunoglobulin-Bound Biomarkers That Predict the Response to Chemotherapy of Pancreatic Cancer Patients

Pancreatic Ductal Adenocarcinoma (PDA) is an aggressive malignancy with a very poor outcome. Although chemotherapy (CT) treatment has poor efficacy, it can enhance tumor immunogenicity. Tumor-Associated Antigens (TAA) are self-proteins that are overexpressed in tumors that may induce antibody production and can be PDA theranostic targets. However, the prognostic value of TAA-antibody association as Circulating Immune Complexes (CIC) has not yet been elucidated, mainly due to the lack of techniques that lead to their identification. In this study, we show a novel method to separate IgG, IgM, and IgA CIC from sera to use them as prognostic biomarkers of CT response. The PDA Immune-Complexome (IC) was identified using a LTQ-Orbitrap mass spectrometer followed by computational analysis. The analysis of the IC of 37 PDA patients before and after CT revealed differential associated antigens (DAA) for each immunoglobulin class. Our method identified different PDA-specific CIC in patients that were associated with poor prognosis patients. Finally, CIC levels were significantly modified by CT suggesting that they can be used as effective prognostic biomarkers to follow CT response in PDA patients.