The COVID-19 pandemic, caused by the coronavirus SARS-CoV-2, is the most severe public health event of the twenty-first century. While effective vaccines against SARS-CoV-2 have been developed, there remains an urgent need for diagnostics to quickly and accurately detect infections. Antigen tests, particularly those that detect the abundant SARS-CoV-2 Nucleocapsid protein, are a proven method for detecting active SARS-CoV-2 infections. Here we report high-resolution crystal structures of three llama-derived single-domain antibodies that bind the SARS-CoV-2 Nucleocapsid protein with high affinity. Each antibody recognizes a specific folded domain of the protein, with two antibodies recognizing the N-terminal RNA binding domain and one recognizing the C-terminal dimerization domain. The two antibodies that recognize the RNA binding domain affect both RNA binding affinity and RNA-mediated phase separation of the Nucleocapsid protein. All three antibodies recognize highly conserved surfaces on the Nucleocapsid protein, suggesting that they could be used to develop affordable diagnostic tests to detect all circulating SARS-CoV-2 variants.

One major obstacle to the design of a global HIV-1 vaccine is viral diversity. Presently, data suggest that a single antigen will not suffice to generate broadly reactive neutralizing antibodies to protect all individuals against all subtypes of HIV-1 infection. While some of the neutralizing epitopes are identified in the constant regions of the HIV-1 envelope (Env) glycoprotein, many are localized to variable regions and differ conformationally from one virus to the next. The successes of polyvalent vaccine approaches against other antigenically variable pathogens encourage adoption of the same approach for HIV-1 vaccine design. The critical question is which envelope antigens should be combined in a vaccine cocktail to provide maximum protection against HIV-1. A review of the existing human vaccines based on the polyvalent principle is included here to provide a historical perspective for the current effort of developing a polyvalent HIV-1 vaccine. Data generated from several groups actively working on candidate polyvalent HIV-1 vaccines are summarized. Information presented in this review highlights the potential and importance of the polyvalent vaccine approach for the future development of an effective HIV-1 vaccine.

ObjectiveProbiotics can modulate immune responses to resist influenza infection. This study aims to evaluate the anti-viral efficacy of B. dorei.MethodsC57BL/6J mice were infected with influenza virus together with treatment of PBS vehicle, B. dorei, or oseltamivir respectively. Anti-influenza potency of B. dorei and the underlying mechanism were determined by measuring survival rate, lung viral load and pathology, gene expression and production of cytokines and chemokines, and analysis of gut microbiota.ResultsAdministration of B. dorei increased (by 30%) the survival of influenza-infected mice, and improved their weight loss, lung pathology, lung index, and colon length compared to the vehicle control group. B. dorei treatment reduced (by 61%) the viral load of lung tissue and increased expression of type 1 interferon more rapidly at day 3 postinfection. At day 7 postinfection, B. dorei-treated mice showed lower local (lung) and systemic (serum) levels of interferon and several proinflammatory cytokines or chemokines (IL-1β, IL-6, TNF-α, IL-10, MCP-1 and IP-10) with a efficacy comparable to oseltamivi treatment. B. dorei treatment also altered gut microbiota as indicated by increased levels of Bacteroides, Prevotella, and Lactobacillus and decreased levels of Escherichia, Shigella, and Parabacteroides.ConclusionB. dorei has anti-influenza effect. Its working mechanisms involve promoting earlier interferon expression and down-regulating both local and systemic inflammatory response. B. dorei changes the composition of gut microbiota, which may also contribute to its beneficial effects.

Cell membrane chromatography (CMC) has been widely used for characterizing the interaction between drugs and membrane receptors to screen target components from herbal medicines. However, the column life, stability, and the efficiency cannot meet the needs of high-throughput screening purpose. In this study, a P-glycoprotein immobilized cell membrane stationary phase (P-gp/CMSP) was prepared with a simple and mild twostep aldehyde modification, realizing the covalent bonding between cell membrane and stationary phase. The column life and stability were significantly enhanced compared with the unmodified columns. The P-gp/CMC column was equipped into a comprehensive 2D P-gp/CMC/Capcell-C18/TOFMS system, which actualizes the automated and high-throughput analytical process and rapid identification of complex chemical samples with no data loss. Five compounds with significant retention were screened out and unambiguously identified by the comprehensive 2D analytical system. Baicalin was confirmed as a P-gp inhibitor with ATP depletion inhibition ratio of 83.4%. Moreover, the reversal index of baicalin on DOX significantly increased to 11.13 when its concentration reached 25 μM, revealing that baicalin could effectively reverse the MDR cell model induced by DOX. The integrated system is a practical drug discovery platform and could be applied to other transmembrane protein models.