Clinical application of SARS-CoV-2 antibody detection and monoclonal antibody therapies against COVID-19

Single Ferritin Nanocages Expressing SARS-CoV-2 Spike Variants to Receptor and Antibodies

SARS-CoV-2 virus variants of concern (VOCs) have rapidly changed their transmissibility and pathogenicity primarily through mutations in the structural proteins. Herein, we present molecular details with dynamics of the ferritin nanocages stitched with synthetic chimeras displaying the Spike receptor binding domains (RBDs). Our findings demonstrated the potential usage of ferritin-based vaccines that may effectively inhibit viral entry by blocking the Spike-ACE2 network and may induce cross-protective antibody responses. Taking the nanocage constructs into consideration, we evaluated the effects of variants on the docked interface of the SARS-CoV-2 Spike RBD with the ACE2 (angiotensin-converting enzyme 2) host cell receptor and neutralizing antibodies (Abs). Investigating the VOCs revealed that most of the mutations reported a possibly reduced structural stability within the Spike RBD domain. Point mutations have moderate or no effect for VVH-72, CR3022, and S309 Abs when bound with the Spike RBD, whereas a significant effect was observed for B38, CB6, and m396 over the surface of the H-ferritin nanocage. In addition to providing useful therapeutic approaches against COVID-19 (coronavirus disease 2019), these structural details can also be used to fight future coronavirus outbreaks.

Preparation of dyed polymer microspheres by a physical-chemical dual-binding method and their application in lateral flow immunoassay

Lateral flow immunoassay (LFIA) has shown great competitiveness in point-of-care testing due to its flexibility and simplicity. Dyed polymer microspheres are one of the most widely used marker particles for signal presentation as they are very convenient for visual interpretation, which is one of the most attractive features of LFIA. The color intensity, as the most critical factor, is directly related to the visual effect. In this work, a physical-chemical dual-binding strategy was proposed for the preparation of functionalized dyed microspheres. Bifunctional seed microspheres were synthesized by introducing 4-vinylbenzyl chloride (VBC) into the soap-free emulsion polymerization process, and the effective immobilization of dyes inside and on the surface of the polymer microspheres was achieved by covalent bonding and swelling methods. The microspheres were characterized by SEM, FT-IR spectroscopy and UV-vis spectroscopy. The results showed that the microspheres containing VBC were spherical with an average particle size of 300 nm. When the microspheres were prepared by adding 10 wt% VBC relative to the total monomer, the immobilization amount of 1-[[4-[(dimethylphenyl)azo]dimethyl phenyl]azo]-2-naphthol (Red-27) was increased to 180 mg g-1, which was 1.8 times that of the microspheres without VBC. The resulting nanomaterials were successfully used to establish a lateral flow immunoassay for the detection of COVID-19 virus N protein. The linear response concentration range was 2.64-87.84 COI, and the detection limit was 14.95 COI.

Human and animal exposure to newly discovered sand fly viruses, China

Introduction

The Hedi virus (HEDV) and Wuxiang virus (WUXV) are newly discovered Bunyaviruses transmitted by sandflies. The geographical distribution of isolation of these two viruses continues to expand and it has been reported that WUXV causes neurological symptoms and even death in suckling mice. However, little is known about the prevalence of the two viruses in mammalian infections.

Methods

In order to understand the infection status of HEDV and WUXV in humans and animals from regions where the viruses have been isolated, this study used Western blotting to detect the positive rates of HEDV and WUXV IgG antibodies in serum samples from febrile patients, dogs, and chickens in the forementioned regions.

Results

The results showed that of the 29 human serum samples, 17.24% (5/29) tested positive for HEDV, while 68.96% (20/29) were positive for WUXV. In the 31 dog serum samples, 87.10% (27/31) were positive for HEDV and 70.97% (22/31) were positive for WUXV, while in the 36 chicken serum samples, 47.22% (17/36) were positive for HEDV, and 52.78% (19/36) were positive for WUXV.

Discussion

These findings suggest there are widespread infections of HEDV and WUXV in mammals (dogs, chickens) and humans from the regions where these viruses have been isolated. Moreover, the positive rate of HEDV infections was higher in local animals compared to that measured in human specimens. This is the first seroepidemiological study of these two sandfly-transmitted viruses. The findings of the study have practical implications for vector-borne viral infections and related zoonotic infections in China, as well as providing an important reference for studies on the relationship between sandfly-transmitted viruses and zoonotic infections outside of China.

Development of a neutralization monoclonal antibody with a broad neutralizing effect against SARS-CoV-2 variants

BACKGROUND

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has challenged the effectiveness of current therapeutic regimens. Here, we aimed to develop a potent SARS-CoV-2 antibody with broad neutralizing effect by screening a scFv library with the spike protein receptor-binding domain (RBD) via phage display.

METHODS

SKAI-DS84 was identified through phage display, and we performed pseudovirus neutralization assays, authentic virus neutralization assays, and in vivo neutralization efficacy evaluations. Furthermore, surface plasmon resonance (SPR) analysis was conducted to assess the physical characteristics of the antibody, including binding kinetics and measure its affinity for variant RBDs.

RESULTS

The selected clones were converted to human IgG, and among them, SKAI-DS84 was selected for further analyses based on its binding affinity with the variant RBDs. Using pseudoviruses, we confirmed that SKAI-DS84 was strongly neutralizing against wild-type, B.1.617.2, B.1.1.529, and subvariants of SARS-CoV-2. We also tested the neutralizing effect of SKAI-DS84 on authentic viruses, in vivo and observed a reduction in viral replication and improved lung pathology. We performed binding and epitope mapping experiments to understand the mechanisms underlying neutralization and identified quaternary epitopes formed by the interaction between RBDs as the target of SKAI-DS84.

CONCLUSIONS

We identified, produced, and tested the neutralizing effect of SKAI-DS84 antibody. Our results highlight that SKAI-DS84 could be a potential neutralizing antibody against SARS-CoV-2 and its variants.