Xin Zhao

Background: Continuous SARS-CoV-2 Omicron emergence poses challenges to immune protection from the previous infection/vaccination in the population. While neutralizing antibodies serve as a key immune protection indicator, their cross-protective effect against novel variants remains limited. However, T cell immunity may confer more durable and broad-spectrum protection. Methods: We evaluated immune dynamics in four Chinese cohorts comprising BF.7/BA.5.2, XBB, and JN.1 convalescents, plus tetravalent recombinant protein vaccine recipients. Neutralizing antibodies were assessed against nine variants spanning the emerging evolutionary spectrum. T cell responses were characterized using variant-specific peptide pools. Antigenic relationships were analyzed through multidimensional scaling-based cartography. Results: BF.7/BA.5.2 convalescents exhibited progressive antibody evasion, with fold-changes against heterologous variants increasing from 4–12-fold initially to > 20-fold at 6 months. XBB convalescents maintained stable short-term responses, while JN.1 convalescents showed superior cross-reactivity against descendant lineages. BA.3.2 demonstrated maximal immune evasion across all groups, occupying the most distant antigenic position. In contrast, T cell immunity exhibited remarkable stability and cross-reactivity, maintaining elevated levels at 6 months with balanced responses against all tested variants. The tetravalent vaccine induced broad-spectrum T cell responses comparable to natural infection, and elicited cross-neutralizing antibody responses against different Omicron variants. Discussion: Our study reveals SARS-CoV-2 variant-specific antibody escape compensated by stable cross-reactive T cell responses. In the context of continued viral evolution, stimulating robust T cell immune responses may be critical to achieve a high population immune barrier against future coronaviruses/variants. These findings emphasize the necessity of comprehensive immune evaluation integrating both humoral and cellular components and provide scientific foundations for optimizing vaccine strategies and immune surveillance systems to address emerging viruses and their variants.

African swine fever (ASF) has caused a devastating pandemic among domestic and wild swine, leading to significant economic losses in the global swine industry. Recombinant live-attenuated vaccines are a potential option for the control of ASF. However, safe and effective vaccines against the ASF virus (ASFV) are not yet commercially available, and thus, additional vaccine candidates still need to be developed. In this study, we demonstrate that the simultaneous deletion of the ASFV genes CD2v and A137R from the highly virulent isolate ASFV HuB/HH/2019 substantially attenuated the virulence in swine. All pigs (4/4) infected with 10 ⁵ TCID ₅₀ doses of the double gene deletion virus HuB/HH/2019Δ CD2v Δ A137R (HuBΔ CD2v Δ A137R ) remained healthy during a 27-day observation period, with no fevers (>40.5°C) observed. Cases of viremia were mild and cleared by 24 days post-inoculation (dpi). Antibodies against ASFV p30 were induced, and the inoculated pigs were well-protected against homologous challenges. All inoculated pigs survived after being challenged with 10 ² HAD ₅₀ ASFV HuB/HH/2019, and no fever or clinical symptoms developed during the 22-day monitoring period. In contrast, all control group pigs died before 11 dpi (2/2). Cytokine assays and RNA sequencing revealed mild responses elicited by HuBΔ CD2v Δ A137R . Successful innate and passive immune responses were also triggered. The findings suggest that deletion of the CD2v and A137R genes can attenuate ASFV, and the deletion mutant virus HuBΔ CD2v Δ A137R is a promising vaccine candidate. IMPORTANCE: The emergence of ASF has caused substantial economic losses in the global pig industry. In light of this, the development of a safe and effective vaccine is crucial to control the spread of ASF. In this study, a live-attenuated ASFV strain was developed by simultaneously knocking out the viral genes CD2v and A137R . The mutant virus exhibited weakened virulence in pigs, elicited robust humoral and cellular immunity, and conferred protection upon challenge with high doses of the parental virus. Notably, no fever or clinical symptoms were observed during a 27-day monitoring period. Consequently, our research presents a highly promising candidate strain for a live-attenuated vaccine, offering a significant step forward in the quest for effective prevention measures. Additionally, the identification of these specific gene targets opens up avenues for further exploration and refinement of strategies aimed at combating ASF outbreaks.

The cotton rat ( Sigmodon hispidus ) has emerged as a preclinical model for human respiratory syncytial virus (RSV) research because of its ability to support effective viral replication and recapitulate disease; however, the mechanisms supporting this evolutionarily conserved phenotype remain unclear. Here, we report both the chromosomal genome and respiratory single-cell transcriptomic atlas of the cotton rat throughout the course of RSV infection. Phylogenetic analysis showed that cotton rats are in different evolutionary branches from common mouse and rat models and exhibit substantial conservation of tissue profiles with humans. The respiratory cell atlas, alveolar cell trajectory, and distribution of potential viral receptors are also similar to those of humans, explaining the superiority of cotton rats as an RSV infection model. The target cells of RSV, including club cells, secretory2 cells, mesothelial cells, and nerve-associated astrocytes, were expanded after infection. We also identified differential transcriptional regulators, specific antiviral proteins, and cytokines that could be translated into potential clinical markers in humans. Candidate host factors were also identified, which will enable the exploration of host-RSV interactions and offer a source of therapeutic targets.

In eukaryotic systems, three major types of cell junctions have been well characterized. While bacterial adhesion mechanisms also exhibit remarkable diversity, the molecular processes that regulate the dynamic modulation of binding strength between elongated bacterial cells and host cells remain poorly understood. Fusobacterium nucleatum ( F. nucleatum ) utilizes the surface adhesin CbpF to interact with the highly expressed host receptors CEACAM1 and CEACAM5 on cancer cells to facilitate tumor colonization. By elucidating the structural details of CbpF binding to human CEACAM1/CEACAM5 receptors, and through mechanistic investigations, we identified that the prominent EFNGQYQ loop on CbpF and the key Q78 residue of CEACAM1/CEACAM5 constitute the molecular linchpin of this pathogen–host interface. Furthermore, we found a distinct type of binding particle and proposed a Velcro-like adhesion model. In this model, CbpF mediates robust attachment through the simultaneous interaction of multiple binding sites, akin to the interlocking mechanism of Velcro. This multivalent interaction allows F. nucleatum to dynamically switch between firm anchoring and easy detachment, adapting to varying physiological microenvironments. Our study elucidates the dynamic modulation of bacterial adhesion strength and lays the foundation for developing therapeutic interventions to disrupt the bacterium–host interface.

Coxsackievirus A10 (CV-A10) infection, a prominent cause of childhood hand-foot-and-mouth disease (HFMD), frequently manifests with the intriguing phenomenon of onychomadesis, characterized by nail shedding. However, the underlying mechanism is elusive. Here, we found that CV-A10 infection in mice could suppress Wnt/β-catenin signaling by restraining LDL receptor–related protein 6 (LRP6) phosphorylation and β-catenin accumulation and lead to onychomadesis. Mechanistically, CV-A10 mimics Dickkopf-related protein 1 (DKK1) to interact with Kringle-containing transmembrane protein 1 (KRM1), the CV-A10 cellular receptor. We further found that Wnt agonist (GSK3β inhibitor) CHIR99021 can restore nail stem cell differentiation and protect against nail shedding. These findings provide novel insights into the pathogenesis of CV-A10 and related viruses in onychomadesis and guide prognosis assessment and clinical treatment of the disease.

There have been reports of long coronavirus disease (long COVID) and breakthrough infections (BTIs); however, the mechanisms and pathological features of long COVID after Omicron BTIs remain unclear. Assessing long-term effects of COVID-19 and immune recovery after Omicron BTIs is crucial for understanding the disease and managing new-generation vaccines. Here, we followed up mild BA.2 BTI convalescents for six-month with routine blood tests, proteomic analysis and single-cell RNA sequencing (scRNA-seq). We found that major organs exhibited ephemeral dysfunction and recovered to normal in approximately six-month after BA.2 BTI. We also observed durable and potent levels of neutralizing antibodies against major circulating sub-variants, indicating that hybrid humoral immunity stays active. However, platelets may take longer to recover based on proteomic analyses, which also shows coagulation disorder and an imbalance between anti-pathogen immunity and metabolism six-month after BA.2 BTI. The immunity-metabolism imbalance was then confirmed with retrospective analysis of abnormal levels of hormones, low blood glucose level and coagulation profile. The long-term malfunctional coagulation and imbalance in the material metabolism and immunity may contribute to the development of long COVID and act as useful indicator for assessing recovery and the long-term impacts after Omicron sub-variant BTIs.