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American tegumentary leishmaniasis (TL) caused by Leishmania braziliensis is characterized by a spectrum of clinical presentations, ranging from localized cutaneous ulcers (CL), mucosal (ML), or disseminated (DL) disease, to a subclinical (SC) asymptomatic form. Current diagnosis based on parasite culture and/or microscopy lacks sensitivity and specificity. Previous studies showed that patients with CL and ML have very high levels of Leishmania-specific anti-α-Gal antibodies. However, the native parasite α-Gal glycotope(s) is(are) still elusive, thus they have not yet been explored for a more accurate TL diagnosis. Using a chemiluminescent immunoassay, we evaluated the seroreactivity of TL patients across its clinical spectrum, and of endemic (EC) and nonendemic healthy controls (NEC) against three synthetic neoglycoproteins (NGP29b, NGP30b, and NGP28b), respectively comprising the L. major-derived type-2 glycoinositolphospholipid (GIPL)-1 (Galfβ1,3Manα), GIPL-2 (Galα1,3Galfβ1,3Manα), and GIPL-3 (Galα1,6Galα1,3Galfβ) glycotopes. Contrary to NGP29b and NGP30b, NGP28b exhibited high sensitivity and specificity to a CL serum pool. More importantly, NGP28b reacted strongly and specifically with individual sera from distinct clinical forms of TL, especially with SC sera, with 94% sensitivity and 97% specificity, by post-two-graph receiver-operating characteristic curve analysis. Contrary to NGP29b, NGP28b showed low cross-reactivity with Chagas disease and control (NEC/EC) sera. Additionally, seroreactivity of CL patients against NGP28b was significantly decreased after successful chemotherapy, indicating that L. braziliensis-specific anti-α-Gal antibodies may serve as an early biomarker of cure in CL. Our data also points towards the applicability of L. major type-2 GIPL-3-derived Galα1,6Galα1,3Galfβ glycotope for the serological diagnosis of American TL, particularly of the subclinical form.

Chagas disease (CD) is caused by the parasite Trypanosoma cruzi and affects 6–7 million people worldwide. The diagnosis is still challenging, due to extensive parasite diversity encompassing seven genotypes (TcI-VI and Tcbat) with diverse ecoepidemiological, biological, and pathological traits. Chemotherapeutic intervention is usually effective but associated with severe adverse events. The development of safer, more effective therapies is hampered by the lack of biomarker(s) (BMKs) for the early assessment of therapeutic outcomes. The mammal-dwelling trypomastigote parasite stage expresses glycosylphosphatidylinositol-anchored mucins (tGPI-MUC), whose O-glycans are mostly branched with terminal, nonreducing α-galactopyranosyl (α-Gal) glycotopes. These are absent in humans, and thus highly immunogenic and inducers of specific CD anti-α-Gal antibodies. In search for α-Gal-based BMKs, here we describe the synthesis of neoglycoprotein NGP11b, comprised of a carrier protein decorated with the branched trisaccharide Galα(1,2)[Galα(1,6)]Galβ. By chemiluminescent immunoassay using sera/plasma from chronic CD (CCD) patients from Venezuela and Mexico and healthy controls, NGP11b exhibited sensitivity and specificity similar to that of tGPI-MUC from genotype TcI, predominant in those countries. Preliminary evaluation of CCD patients subjected to chemotherapy showed a significant reduction in anti-α-Gal antibody reactivity to NGP11b. Our data indicated that NGP11b is a potential BMK for diagnosis and treatment assessment in CCD patients.

With the emergence of SARS-CoV-2 variants, there is urgent need to develop broadly neutralizing antibodies. Here, we isolate two VHH nanobodies (7A3 and 8A2) from dromedary camels by phage display, which have high affinity for the receptor-binding domain (RBD) and broad neutralization activities against SARS-CoV-2 and its emerging variants. Cryo-EM complex structures reveal that 8A2 binds the RBD in its up mode and 7A3 inhibits receptor binding by uniquely targeting a highly conserved and deeply buried site in the spike regardless of the RBD conformational state. 7A3 at a dose of ≥5 mg/kg efficiently protects K18-hACE2 transgenic mice from the lethal challenge of B.1.351 or B.1.617.2, suggesting that the nanobody has promising therapeutic potentials to curb the COVID-19 surge with emerging SARS-CoV-2 variants., One-Sentence Summary: Dromedary camel (Camelus dromedarius) VHH phage libraries were built for isolation of the nanobodies that broadly neutralize SARS-CoV-2 variants.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of the Coronavirus disease 2019 (Covid-19) pandemic, continues to evolve and circulate globally. Current prophylactic and therapeutic countermeasures against Covid-19 infection include vaccines, small molecule drugs, and neutralizing monoclonal antibodies. SARS-CoV-2 infection is mainly mediated by the viral spike glycoprotein binding to angiotensin converting enzyme 2 (ACE2) on host cells for viral entry. As emerging mutations in the spike protein evade efficacy of spike-targeted countermeasures, a potential strategy to counter SARS-CoV-2 infection is to competitively block the spike protein from binding to the host ACE2 using a soluble recombinant fusion protein that contains a human ACE2 and an IgG1-Fc domain (ACE2-Fc). Here, we have established Chinese Hamster Ovary (CHO) cell lines that stably express ACE2-Fc proteins in which the ACE2 domain either has or has no catalytic activity. The fusion proteins were produced and purified to partially characterize physicochemical properties and spike protein binding. Our results demonstrate the ACE2-Fc fusion proteins are heavily N-glycosylated, sensitive to thermal stress, and actively bind to five spike protein variants (parental, alpha, beta, delta, and omicron) with different affinity. Our data demonstrates a proof-of-concept production strategy for ACE2-Fc fusion glycoproteins that can bind to different spike protein variants to support the manufacture of potential alternative countermeasures for emerging SARS-CoV-2 variants.

Current treatment for Chagas disease with the only available drugs, benznidazole or nifurtimox, has substantial limitations, including long treatment duration and safety and tolerability concerns. We aimed to evaluate the efficacy and safety of new benznidazole monotherapy regimens and combinations with fosravuconazole, in the treatment of Chagas disease.We did a double-blind, double-dummy, phase 2, multicentre, randomised trial in three outpatient units in Bolivia. Adults aged 18-50 years with chronic indeterminate Chagas disease, confirmed by serological testing and positive qualitative PCR results, were randomly assigned (1:1:1:1:1:1:1) to one of seven treatment groups using a balanced block randomisation scheme with an interactive response system. Participants were assigned to benznidazole 300 mg daily for 8 weeks, 4 weeks, or 2 weeks, benznidazole 150 mg daily for 4 weeks, benznidazole 150 mg daily for 4 weeks plus fosravuconazole, benznidazole 300 mg once per week for 8 weeks plus fosravuconazole, or placebo, with a 12-month follow-up period. The primary endpoints were sustained parasitological clearance at 6 months, defined as persistent negative qualitative PCR results from end of treatment, and incidence and severity of treatment-emergent adverse events, serious adverse events, and adverse events leading to treatment discontinuation. Primary efficacy analysis was based on the intention-to-treat and per-protocol populations and secondary efficacy analyses on the per-protocol population. Safety analyses were based on the as-treated population. Recruitment is now closed. This trial is registered with ClinicalTrials.gov, NCT03378661.Between Nov 30, 2016, and July 27, 2017, we screened 518 patients, and 210 were enrolled and randomised. 30 patients (14%) were assigned to each treatment group. All 210 randomised patients were included in the intention-to-treat population, and 190 (90%) were included in the per-protocol population. In the intention-to-treat analysis, only one (3%) of 30 patients in the placebo group had sustained parasitological clearance at 6 months of follow-up. Sustained parasitological clearance at 6 months was observed in 25 (89%) of 28 patients receiving benznidazole 300 mg daily for 8 weeks (rate difference vs placebo 86% [95% CI 73-99]), 25 (89%) of 28 receiving benznidazole 300 mg daily for 4 weeks (86% [73-99]), 24 (83%) of 29 receiving benznidazole 300 mg daily for 2 weeks (79% [64-95]), 25 (83%) of 30 receiving benznidazole 150 mg daily for 4 weeks (80% [65-95]), 23 (85%) of 28 receiving benznidazole 150 mg daily for 4 weeks plus fosravuconazole (82% [67-97]), and 24 (83%) of 29 receiving benznidazole 300 mg weekly for 8 weeks plus fosravuconazole (79% [64-95]; p0·0001 for all group comparisons with placebo). Six patients (3%) had ten serious adverse events (leukopenia [n=3], neutropenia [n=2], pyrexia, maculopapular rash, acute cholecystitis, biliary polyp, and breast cancer), eight had 12 severe adverse events (defined as interfering substantially with the patient's usual functions; elevated alanine aminotransferase [n=4], elevated gamma-glutamyltransferase [n=2], elevated aspartate aminotransferase [n=1], neutropenia [n=3], leukopenia [n=1], and breast cancer [n=1]), and 15 (7%) had adverse events that led to treatment discontinuation (most of these were in the groups who received benznidazole 300 mg daily for 8 weeks, benznidazole 300 mg once per week for 8 weeks plus fosravuconazole, and benznidazole 150 mg daily for 4 weeks plus fosravuconazole). No adverse events leading to treatment discontinuation were observed in patients treated with benznidazole 300 mg daily for 2 weeks or placebo. There were no treatment-related deaths.Benznidazole induced effective antiparasitic response, regardless of treatment duration, dose, or combination with fosravuconazole, and was well tolerated in adult patients with chronic Chagas disease. Shorter or reduced regimens of benznidazole could substantially improve treatment tolerability and accessibility, but further studies are needed to confirm these results.Drugs for Neglected Diseases initiative (DNDi).For the Spanish translation of the abstract see Supplementary Materials section.

Chagas disease (ChD), caused by the protozoan parasite Trypanosoma cruzi, affects millions of people worldwide. Chemotherapy is restricted to two drugs, which are partially effective and may cause severe side effects, leading to cessation of treatment in a significant number of patients. Currently, there are no biomarkers to assess therapeutic efficacy of these drugs in the chronic stage. Moreover, no preventive or therapeutic vaccines are available. In this chapter, we describe the purification of Trypanosoma cruzi trypomastigote-derived glycosylphosphatidylinositol (GPI)-anchored mucins (tGPI-mucins) for their use as antigens for the reliable primary or confirmatory diagnosis and as prognostic biomarkers for early assessment of cure following ChD chemotherapy. We also describe, as an example, the synthesis of a potential tGPI-mucin-derived α-Gal-terminating glycan and its coupling to a carrier protein for use as diagnostic and prognostic biomarker in ChD.