Search

SARS‐CoV‐2 continues to mutate, leading to breakthrough infections. The development of new vaccine strategies to combat various strains is crucial. Protein cyclization can enhance thermal stability and may improve immunogenicity. Here, we designed a cyclic tandem dimeric receptor‐binding domain protein (cirRBD2) via the split intein Cth‐Ter. Cyclization does not affect the antigen epitopes of RBD but results in better thermal stability than that of its linear counterpart (linRBD2). Compared with the mice immunized with linRBD2, those immunized with two doses of 5 μg of cirRBD2 produced significantly greater levels of broad‐spectrum neutralizing antibodies, and generated a considerable cellular immune response. In the VEEV‐VRP‐hACE2‐transduced mouse model, two doses of 5 μg of cirRBD2 provided protection against infection with BA.5, XBB.1.9, and partial protection against EG.5 which has more mutations. This study developed a novel circular RBD dimer subunit vaccine for SARS‐CoV‐2 that exhibits broad‐spectrum neutralizing activity against various variants. A similar strategy can be applied to develop vaccines for other pathogens, especially for thermally stable vaccines. [ABSTRACT FROM AUTHOR]

Enteroviruses such as coxsackievirus B3 are identified as a common cause of viral myocarditis, but the potential mechanism of its replication and pathogenesis are largely unknown. The genomes of a variety of viruses contain N6-methyladenosine (m6A), which plays important roles in virus replication. Here, by using the online bioinformatics tools SRAMP and indirect immunofluorescence assay (IFA), we predict that the CVB3 genome contains m6A sites and found that CVB3 infection could alter the expression and cellular localization of m6A-related proteins. Moreover, we found that 3-deazaadenosine (3-DAA), an m6A modification inhibitor, significantly decreased CVB3 replication. We also observed that the m6A methyltransferases methyltransferase-like protein 3 (METTL3) and METTL14 play positive roles in CVB3 replication, whereas m6A demethylases fat mass and obesity-associated protein (FTO) or AlkB homolog 5 (ALKBH5) have opposite effects. Knockdown of the m6A binding proteins YTH domain family protein 1 (YTHDF1), YTHDF2 and YTHDF3 strikingly decreased CVB3 replication. Finally, the m6A site mutation in the CVB3 genome decreased the replication of CVB3 compared with that in the CVB3 wild-type (WT) strain. Taken together, our results demonstrated that CVB3 could exploit m6A modification to promote viral replication, which provides new insights into the mechanism of the interaction between CVB3 and the host. [ABSTRACT FROM AUTHOR]

Receptor binding is the first step for virus infection. In this issue of Cell Host & Microbe , Gorka et al. conducted large-scale receptor binding assays with machine learning to predict susceptible host species and guide proactive filovirus surveillance. This study provides multidisciplinary blueprints for research and prevention of zoonotic disease. [ABSTRACT FROM AUTHOR]

Major diseases, such as cancer and COVID‐19, are frightening global health problems, and sustained action is necessary to develop vaccines. Here, for the first time, ethoxy acetalated dextran nanoparticles (Ace‐Dex‐NPs) are functionalized with 9‐N‐(4H‐thieno[3,2‐c]chromene‐2‐carbamoyl)‐Siaα2−3Galβ1−4GlcNAc (TCCSia‐LacNAc) targeting macrophages as a universal vaccine design platform. First, azide‐containing oxidized Ace‐Dex‐NPs are synthesized. After the NPs are conjugated with ovalbumin (OVA) and resiquimod (Rd), they are coupled to TCCSia‐LacNAc‐DBCO to produce TCCSia‐Ace‐Dex‐OVA‐Rd, which induce a potent, long‐lasting OVA‐specific cytotoxic T‐lymphocyte (CTL) response and high anti‐OVA IgG, providing mice with superior protection against tumors. Next, this strategy is exploited to develop vaccines against infection by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2). The receptor‐binding domain (RBD) of the SARS‐CoV‐2 spike protein is the main target for neutralizing antibodies. The TCCSia‐Ace‐Dex platform is preferentially used for designing an RBD‐based vaccine. Strikingly, the synthetic TCCSia‐Ace‐Dex‐RBD‐Rd elicited potent RBD‐neutralizing antibodies against live SARS‐CoV‐2 infected Vero E6 cells. To develop a universal SARS‐CoV‐2 vaccine, the TCCSia‐Ace‐Dex‐N‐Rd vaccine carrying SARS‐CoV‐2 nucleocapsid protein (N) is also prepared, which is highly conserved among SARS‐CoV‐2 and its variants of concern (VOCs), including Omicron (BA.1 to BA.5); this vaccine can trigger strong N‐specific CTL responses against target cells infected with SARS‐CoV‐2 and its VOCs. [ABSTRACT FROM AUTHOR]

Objective: Monkey B virus (BV) infection in humans and other macaque species has a mortality rate of approximately 80%. Because BV infects humans through bites, scratches, and other injuries inflicted by macaques, the simple and rapid diagnosis of BV in field laboratories is of great importance to protect veterinarians, laboratory researchers, and support personnels from the threat of infection. Methods: Two recombinase polymerase amplification (RPA) assays with a closed vertical flow (VF) visualization strip (RPA-VF-UL27 and RPA-VF-US6) were developed that target two conserved genes combined with a one-off, closed visualization strip device. We compared the sensitivities and specificities of the two assays after optimization of the reaction conditions. The performance of RPA-VF-US6 at room temperature was determined to evaluate its potential in point-of-care (POC) testing. Result: RPA-VF-US6 specifically detected the positive plasmid control (rather than nucleic acids of herpesviruses) with a detection limit of 28 copies, while RPA-VF-UL27 had cross-reactivity with HSV-1, but even 3.4 copies of plasmid standards were readout by this assay. Moreover, RPA-VF-US6 had excellent performance at room temperature (the detection limit was 2,800 plasmid copies), indicating the potential of RPA-VF-US6 in POC testing. Conclusion: We developed two RPA assays for BV visualization diagnosis. RPA-VF-US6 is a simple, rapid, and specific detection method for BV. The entire reaction can be performed at a constant temperature within 30 min, suggesting the potential of RPA-VF-US6 for POC testing in field laboratories without sophisticated instruments. [ABSTRACT FROM AUTHOR]

The outbreak of clade II monkeypox virus (MPXV) and the additional outbreak in Central Africa of clade I virus from 2023 have attracted worldwide attention. The development of a scalable and effective vaccine against the ongoing epidemic of mpox is urgently needed. We previously constructed two bivalent MPXV mRNA vaccines, LBA (B6R-A29L) and LAM (A35R-M1R), and a quadrivalent mRNA vaccine, LBAAM (B6R-A35R-A29L-M1R). These vaccines at a 20 µg dose could induce potential MPXV antigen-specific immune responses and provide protection against lethal VACV challenge. Compared with the individual bivalent mRNA vaccines, the two quadrivalent vaccines LBAAM and LBA& LAM displayed superior protective effects. To characterize these vaccines further, we monitored long-term immunity and protection as long as 28 weeks after initial immunization and optimized the immunization dosages to decrease the cost of production for future clinical use. Our results demonstrated that both the bivalent MPXV mRNA vaccine LAM (A35R-M1R) and the two tetravalent vaccines LBAAM and LBA& LAM could elicit long-lasting antigen-specific IgG antibodies as well as neutralizing antibodies against VACV and MPXV. They all provided complete protection against VACV challenge until 28 weeks post prime immunization. Moreover, the immunogenicity and protective efficacy of the two tetravalent vaccines (LBAAM and LBA& LAM) are dose dependent, and even the low-dose (1 µg) vaccine could provide sufficient protection against lethal VACV challenge. These results provide valuable clues for the further production of MPXV mRNA vaccines for use in humans., (© 2024 Wiley Periodicals LLC.)

BACKGROUNDAs Omicron is prompted to replicate in the upper airway, neutralizing antibodies (NAbs) delivered through inhalation might inhibit early-stage infection in the respiratory tract. Thus, elucidating the prophylactic efficacy of NAbs via nasal spray addresses an important clinical need.METHODSThe applicable potential of a nasal spray cocktail containing 2 NAbs was characterized by testing its neutralizing potency, synergetic neutralizing mechanism, emergency protective and therapeutic efficacy in a hamster model, and pharmacokinetics/pharmacodynamic (PK/PD) in human nasal cavity.RESULTSThe 2 NAbs displayed broad neutralizing efficacy against Omicron, and they could structurally compensate each other in blocking the Spike-ACE2 interaction. When administrated through the intranasal mucosal route, this cocktail demonstrated profound efficacy in the emergency prevention in hamsters challenged with authentic Omicron BA.1. The investigator-initiated trial in healthy volunteers confirmed the safety and the PK/PD of the NAb cocktail delivered via nasal spray. Nasal samples from the participants receiving 4 administrations over a course of 16 hours demonstrated potent neutralization against Omicron BA.5 in an ex vivo pseudovirus neutralization assay.CONCLUSIONThese results demonstrate that the NAb cocktail nasal spray provides a good basis for clinical prophylactic efficacy against Omicron infections.TRIAL REGISTRATIONwww.chictr.org.cn, ChiCTR2200066525.FUNDINGThe National Science and Technology Major Project (2017ZX10202203), the National Key Research and Development Program of China (2018YFA0507100), Guangzhou National Laboratory (SRPG22-015), Lingang Laboratory (LG202101-01-07), Science and Technology Commission of Shanghai Municipality (YDZX20213100001556), and the Emergency Project from the Science & Technology Commission of Chongqing (cstc2021jscx-fyzxX0001).

Assessing the long-term efficacy of MPXV vaccine candidates is crucial for the global response to the ongoing mpox epidemic. Built upon our previous study of the mpox quadrivalent mRNA vaccine, herein we reported that MPXV-1103 could elicit sustained humoral and cellular immunity in mice, including the induction of MPXV A35/B6/A29/M1-specific IgG antibodies, VACV neutralizing antibodies and activated cytotoxic CD8 + T cells, which provides 100% protection against lethal VACV challenge even at 280 days after the first vaccination. Our results provide critical insights for orthopoxvirus vaccine development.