Identification of a highly conserved neutralizing epitope within the RBD region of diverse SARS-CoV-2 variants.

The constant emergence of SARS-CoV-2 variants continues to impair the efficacy of existing neutralizing antibodies, especially XBB.1.5 and EG.5, which showed exceptional immune evasion properties. Here, we identify a highly conserved neutralizing epitope targeted by a broad-spectrum neutralizing antibody BA7535, which demonstrates high neutralization potency against not only previous variants, such as Alpha, Beta, Gamma, Delta and Omicron BA.1-BA.5, but also more recently emerged Omicron subvariants, including BF.7, CH.1.1, XBB.1, XBB.1.5, XBB.1.9.1, EG.5. Structural analysis of the Omicron Spike trimer with BA7535-Fab using cryo-EM indicates that BA7535 recognizes a highly conserved cryptic receptor-binding domain (RBD) epitope, avoiding most of the mutational hot spots in RBD. Furthermore, structural simulation based on the interaction of BA7535-Fab/RBD complexes dissects the broadly neutralizing effect of BA7535 against latest variants. Therapeutic and prophylactic treatment with BA7535 alone or in combination with BA7208 protected female mice from the circulating Omicron BA.5 and XBB.1 variant infection, suggesting the highly conserved neutralizing epitope serves as a potential target for developing highly potent therapeutic antibodies and vaccines.

Biparatopic antibody BA7208/7125 effectively neutralizes SARS-CoV-2 variants including Omicron BA.1-BA.5.

SARS-CoV-2 Omicron subvariants have demonstrated extensive evasion from monoclonal antibodies (mAbs) developed for clinical use, which raises an urgent need to develop new broad-spectrum mAbs. Here, we report the isolation and analysis of two anti-RBD neutralizing antibodies BA7208 and BA7125 from mice engineered to produce human antibodies. While BA7125 showed broadly neutralizing activity against all variants except the Omicron sublineages, BA7208 was potently neutralizing against all tested SARS-CoV-2 variants (including Omicron BA.1-BA.5) except Mu. By combining BA7208 and BA7125 through the knobs-into-holes technology, we generated a biparatopic antibody BA7208/7125 that was able to neutralize all tested circulating SARS-CoV-2 variants. Cryo-electron microscopy structure of these broad-spectrum antibodies in complex with trimeric Delta and Omicron spike indicated that the contact residues are highly conserved and had minimal interactions with mutational residues in RBD of current variants. In addition, we showed that administration of BA7208/7125 via the intraperitoneal, intranasal, or aerosol inhalation route showed potent therapeutic efficacy against Omicron BA.1 and BA.2 in hACE2-transgenic and wild-type mice and, separately, effective prophylaxis. BA7208/7125 thus has the potential to be an effective candidate as an intervention against COVID-19.

Structure and function analysis of a potent human neutralizing antibody CA521FALA against SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing COVID-19 pandemic, which has resulted in more than two million deaths at 2021 February . There is currently no approved therapeutics for treating COVID-19. The SARS-CoV-2 Spike protein is considered a key therapeutic target by many researchers. Here we describe the identification of several monoclonal antibodies that target SARS-CoV-2 Spike protein. One human antibody, CA521FALA, demonstrated neutralization potential by immunizing human antibody transgenic mice. CA521FALA showed potent SARS-CoV-2-specific neutralization activity against SARS-CoV-2 pseudovirus and authentic SARS-CoV-2 infection in vitro. CA521FALA also demonstrated having a long half-life of 9.5 days in mice and 9.3 days in rhesus monkeys. CA521FALA inhibited SARS-CoV-2 infection in SARS-CoV-2 susceptible mice at a therapeutic setting with virus titer of the lung reduced by 4.5 logs. Structural analysis by cryo-EM revealed that CA521FALA recognizes an epitope overlapping with angiotensin converting enzyme 2 (ACE2)-binding sites in SARS-CoV-2 RBD in the Spike protein. CA521FALA blocks the interaction by binding all three RBDs of one SARS-CoV-2 spike trimer simultaneously. These results demonstrate the importance for antibody-based therapeutic interventions against COVID-19 and identifies CA521FALA a promising antibody that reacts with SARS-CoV-2 Spike protein to strongly neutralize its activity.

Analytical comparability assessment on glycosylation of ziv-aflibercept and the biosimilar candidate.

Ziv-aflibercept (aflibercept) is a recombinant fusion protein which combines the portions of human vascular endothelial growth factor receptors extracellular domains fused to the Fc portion of human IgG1. It is a highly sialylated glycoprotein with 5 N-glycosylation sites. In this study, a comprehensive strategy for comparability study of the complex glycosylation was developed between aflibercept and the biosimilar candidate including the investigations on N-glycosylation sites, site occupancy, site-specific glycoforms, released glycans and sialic acids. The results indicated that same N-glycosylation sites were identified, site occupancy were 100% except N68 site, site-specific glycoforms and released glycans showed similar glycan species, contents of NANA were at a same level for two products. Minor differences were found between two products. The biosimilar candidate presented lower level of aglycosylation, lower level of glycans containing one terminal sialic acid, higher level of glycans containing two terminal sialic acids, higher level of G0F and Man5, lower level of G1F and G2F compared with aflibercept. However, further studies exhibited no differences were observed in the cell-based biological potency and Fc effector function. Moreover, the biosimilar candidate showed a similar pharmacokinetics curve and bioequivalence compared with aflibercept.

SALL4 is a useful marker for pediatric yolk sac tumors.

BACKGROUND: SALL4 is a zinc finger transcription factor that exerts its physiological role during embryo-fetal development. Analyses of SALL4 expression have shown its oncogenic role in precursor B-cell lymphoblastic lymphoma, acute and chronic myeloid leukemia, gastrointestinal, breast, and lung cancers. The aim of this study was to determine the immunohistochemical profile of SALL4 in pediatric yolk sac tumors (YSTs). METHODS AND RESULTS: Immunohistochemistry detection of SALL4 was performed in 22 cases of pediatric YSTs and 10 mature teratomas. The percentage of tumor cells stained was scored as 0, 1+ (1-30% cells), 2+ (31-60%), 3+ (61-90%), and 4+ (> 90%). To compare its sensitivity and specificity with Glypican-3 and α-fetoprotein (AFP), we also stained tumors from these cases for Glypican-3 and AFP. In contrast to AFP and glypican-3, SALL4 staining in more than 90% of the tumor cells was seen in all 22 pediatric YSTs (100% sensitivity) (P < 0.001 for both SALL4 vs. AFP and SALL4 vs. glypican-3). CONCLUSIONS: SALL4 is a sensitive marker for pediatric YSTs and it can be used to distinguish them from mature teratomas. SALL4 is likely to become a new and valuable biomarker for the diagnosis of pediatric YST.

A comprehensive approach for evaluating charge heterogeneity in biosimilars.

Charge heterogeneity is often evaluated during biosimilar development as it is a universal feature of monoclonal antibodies (mAbs). A common approach in the industry is to develop a biosimilar product with a similar overall charge profile as the reference product. However, uncertainty remains with this approach as the same charge profile in two different products may be caused by different mechanisms. In this work, we present a comprehensive investigation of the charge variants of a therapeutic monoclonal antibody and its biosimilar candidate. Not only did the candidate show a similar charge profile as the reference product, our studies revealed that the same factors contributed to the charge variants of the reference product and the biosimilar candidate. We believe our cause-based approach mitigates the risks associated with the profile-based method and is a rational approach for the charge evaluation of biosimilars.

[Modified Bianchi orchiopexy for median or low cryptorchidism].

OBJECTIVE: To investigate the effect of modified Bianchi (single incision in the midline of the scrotum) orchiopexy (MBO) versus that of traditional surgery in the treatment of median or low cryptorchidism. METHODS: Eighty-two children with median or low cryptorchidism were treated from February 2013 to February 2014, 46 (53 testes) by MBO and the other 36 by the traditional method of inguinal incision (control, 40 testes). Comparisons were made in the operation time and postoperative complications between the two surgical strategies. RESULTS: The mean operation time was significantly shorter in the MBO group than in the control (ï¼»25±6ï¼½ vs ï¼»35±4ï¼½ min, P<0.05). No testicular atrophy, hernias or hydrocele was found in either group during the 1－2 years of follow-up. Testis retraction was observed in 3 cases in the MBO group as compared with 2 in the control (P>0.05). The incision scar was obvious in all the controls, with 1 case of postoperative inguinal hematoma, but almost invisible in all the MBO cases. CONCLUSIONS: Modified Bianchi orchiopexy is superior to traditional surgery in the treatment of median or low cryptorchidism for its advantages of short operation time, few complications, and satisfactory appearance of the healed incision.

Reconstruction of a new pulmonary artery in arterial switch operation.

BACKGROUND: This study was undertaken to evaluate the new method for the reconstruction of the pulmonary artery in arterial switch operation (ASO). METHODS: A total of 108 consecutive infants with congenital heart disease were treated with ASO in our department between January 2004 and June 2012. The new pulmonary arterial root was reconstructed with a fresh autologuos pericardium which was clipped pants-like with continuous mattress suture of 6-0 Prolene thread. Patients were reexamined consecutively at 3 and 6 months and 1, 2 and 6 years after discharge. The pulmonary arterial blood velocity was measured by continuous Doppler during systole. The pulmonary flow of healthy children of same age was also measured in the control group. Simplified Bernoulli formula was used to calculate the pressure gradient via the pulmonary artery for determining whether there was pulmonary stenosis. RESULTS: In this series, 96 infants survived after the surgery and 88 were followed up with a mean peirod of (22±4) months. No pulmonary stenosis was detected with the simplified Bernoulli formula. CONCLUSION: No pulmonary stenosis was detected with the simplified Bernoulli formula.

Posterior mediastinal thymus: case report and literature review.

BACKGROUND: The incidence of aberrant thymus in the posterior mediastinum is very uncommon. It is difficult to exclude malignancy before surgical procedure. CASE PRESENTATION: In a six-month-old male coughing for two weeks prior to admission a posterior mediastinal mass was found incidentally by chest roentgenogram. Thoracotomy was performed. Histologic study revealed normal thymic tissue. CONCLUSION: When a mass located in the posterior mediastinum, ectopic thymus should be included in differential diagnosis. Imaging techniques may spare thoracotomy. Ectopic thymus has a benign clinical course, and surgical resection is not recommended.

Characterization and biotechnological potential of petroleum-degrading bacteria isolated from oil-contaminated soils.

A collection of 38 bacteria was obtained by enrichment cultivation from oil-contaminated soils of an oil field in Daqing, China. Twenty-two strains could utilize diesel oil as the sole source of carbon and energy, and 11 strains could degrade the total petroleum hydrocarbons (TPHs) of diesel oil by more than 70% in 7d. Phylogenetically, 19 of the bacteria related to Bacillus species. About 87.5% TPHs of crude oil were degraded by a consortium of seven strains. Denaturing gradient gel electrophoresis analysis suggested that five of the strains persisted throughout the degradation process. The collection of isolated bacteria might be a useful resource for bioremediation of oil-contaminated soils and biotreatment of oil wastewater.

Methods for the preparation of a biodesulfurization biocatalyst using Rhodococcus sp.

Several methods to prepare a biodesulfurization (BDS) biocatalyst were investigated in this study using a strain of Rhodococcus sp. 1awq. This bacterium could selectively remove sulfur from dibenzothiophene (DBT) via the "4S" pathway. DBT, dimethylsulfoxide (DMSO), sodium sulphate and mixed sulfur sources were used to study their influence on cell density, desulfurization activity, desulfurization ability, and the cost of biocatalyst production. In contrast to that observed from bacteria cultured in DBT, only partial desulfurization activity of strain 1awq was induced by DBT after cultivation in a medium containing inorganic sulfur as the sole sulfur source. The biocatalyst, prepared from culture with mixed sulfur sources, was found to possess desulfurization activity. With DMSO as the sole sulfur source, the desulfurization activity was shown to be similar to that of bacteria incubated in medium with DBT as the sole sulfur source. The biocatalyst prepared by this method with the least cost could remove sulfur from hydrodesulfurization (HDS)-treated diesel oil efficiently, providing a total desulfurization percent of 78% and suggesting its cost-effective advantage.