Enterovirus

Enteroviruses, belonging to the Picornaviridae family, are a group of non-enveloped positive-sense single-strand RNA viruses. These include several viruses, such as echoviruses, coxsackieviruses, and rhinoviruses, which significantly impact human health and can cause diseases like viral encephalitis, hand-foot-and-mouth disease, and other related conditions. Our research focuses on a comprehensive study of enteroviruses, covering receptor discovery, invasion mechanisms, pathogenesis, and tumor immunotherapy. By thoroughly analyzing the interactions between viruses and host receptors, as well as their pathogenic processes, we have provided a solid theoretical foundation and innovative ideas for the prevention, treatment, and drug development of enterovirus-related diseases, and advanced oncolytic virus therapy strategies.

Achievement 1: Uncovered the Enterovirus B Uncoating Receptor and Described the “Dual-Receptor System” Invasion Mechanism

Our team first discovered that the human neonatal Fc receptor (FcRn) serves as the universal uncoating receptor for several Enterovirus B (EV-B). Using Echovirus 6 as an example, we revealed the distinct roles of the attachment and uncoating receptor at atomic or near-atomic resolution, systematically elucidating the invasion mechanism of Enterovirus B into host cells.

Achievement 2: The “Dual-Receptor System” Invasion Mechanism of Enterovirus 11

Enterovirus 11 causes diseases such as encephalitis and meningitis in children, severely threatening human health and public safety. It is one of the major serotypes of EV-B. Our team systematically analyzed the viral and receptor complex structures of Enterovirus 11 at different stages of invasion under various pH conditions, disclosed 10 high-resolution structures. We elucidated the molecular mechanism by which Enterovirus 11 utilizes the attachment receptor CD55 and uncoating receptor FcRn “dual-receptor system” for cell invasion. Unlike Enterovirus 6, Enterovirus 11 initiates conformational changes upon binding to FcRn even under neutral conditions, thus improving the “dual-receptor” invasion model for EV-B.

Achievement 3: Identified Echovirus 18 Receptor FcRn and Revealed Its Invasion Mechanism

Enterovirus 18 is one of the major serotypes responsible for the recent outbreaks of viral encephalitis and meningitis in Chinese children. Our research showed that, unlike enterovirus 6 and 11, enterovirus 18 does not depend on the common attachment receptor CD55, but exclusively utilizes FcRn as the receptor to facilitate both cell surface attachment and uncoating. Furthermore, we confirmed that enterovirus 18, along with genetically closely related enteroviruses such as enterovirus 2 and 15, relies solely on FcRn for infection and invasion. Structural biology studies further revealed the interaction mechanism between enterovirus 18 and FcRn. Thus, we concluded that enterovirus 18’s tissue tropism differs from that of enterovirus 6 and 11, with its infection being more dependent on the expression level of FcRn and not on CD55. These findings have enriched our understanding of the invasion mechanism and tissue tropism of EV-B and provided critical theoretical insights for related viral research and treatments.

Achievement 4: The Molecular Mechanism by Which a Single Point Mutation in Coxsackievirus B3 Affects Receptor Binding

Coxsackievirus B3 (CV-B3) is a major pathogen that causes global myocarditis. Our team identified amino acid distribution at the VP3-234 site of the CV-B3 capsid protein based on sequences from NCBI and clinical strains from across the country. We confirmed that this distribution could lead to differences in the virus's ability to bind to the attachment receptor CD55. By analyzing high-resolution structural of the virus and receptor complexes (CD55 and uncoating receptor CAR) under different pH conditions and at various stages of invasion, we revealed the structural basis of enterovirus’s differential receptor utilization at near-atomic resolution. Additionally, we found that although different CV-B3 strains utilize the same uncoating receptor, their infection process shows pH-dependent invasion patterns. In-depth analysis of enterovirus receptor utilization differences will provide guidance for precision therapy for infections caused by enteroviruses.

Achievement 5: The Invasion Mechanism of Coxsackievirus A10 Utilizing the Dual-Function Receptor KRM1

Coxsackievirus A10 (CV-A10) is a major pathogen causing hand-foot-and-mouth disease, posing a serious health threat to infants and young children worldwide. Our team discovered that Kringle domain-containing transmembrane protein 1 (KRM1) serves as the invasion receptor for CV-A10, mediating both the “attachment” and “uncoating” processes. Structural analysis revealed that KRM1 interacts with the capsid proteins VP1, VP2, and VP3. Notably, the EF-loop of VP2 (amino acids 138-143) may be a key target for receptor recognition. Sequence alignment of Enterovirus A (EV-A) capsid proteins suggests that EV-A relying on KRM1 as a receptor may share a common receptor-binding mode. This study systematically elucidates the molecular mechanism by which KRM1 mediates EV-A invasion, deepening our understanding of enterovirus infections and providing important theoretical support for antiviral therapy.

Achievement 6: Unveiling the Mechanism of Onychomadesis post-HFMD

After recovering from hand-foot-and-mouth disease, children occasionally develop nail abnormalities, leading to onychomadesis or Beau’s line, a clinical phenomenon observed for over 20 years. However, the complexity of the virus-host interaction has hindered progress in understanding and preventing this clinical complication. In 2020, our team revealed the structural basis of CV-A10 invasion via the KRM1 receptor, and during this research, we found that the viral binding interface on KRM1 closely mimics the binding site for the natural ligand DKK1. This suggests that EV-A may use KRM1 to mimic DKK1’s regulatory effects. Our team recorded the process of onychomadesis in neonatal mice infected with CV-A10 and confirmed that CV-A10 infection inhibits the Wnt/β-catenin signaling pathway, affecting nail stem cell differentiation and potentially leading to abnormal nail development. Mechanistically, CV-A10 infection reduced the surface expression and phosphorylation of LRP6, preventing the activation of the Wnt/β-catenin pathway. Based on this, the team explored the use of the signaling pathway agonist CHIR99021 for therapeutic intervention. This study provides a novel perspective on understanding viral pathogenesis and offers important guidance for the treatment and post-infection evaluation of related viral infections.

Achievement 7: Characterisation of Enteroviruses that Modulate Signaling Pathways Could Enable Tumour Therapy

Colorectal cancer is a malignant tumor with high incidence and mortality rates, and conventional treatments face challenges such as chemotherapy resistance or ineffectiveness. Oncolytic viruses represent a novel immunotherapy, capable of directly lysing tumor cells and inducing tumor-specific immune responses while sparing normal cells. Approximately 90% of colorectal cancers are closely related to the abnormal activation of the Wnt signaling pathway, and previous work by our team has shown that CV-A10 infection can inhibit the Wnt/β-catenin signaling pathway, offering the potential for tumor treatment. These findings provide theoretical support for using EV, such as CV-A10, as oncolytic viruses to treat colorectal cancer, laying a crucial foundation for evaluating their clinical application potential.

Achievement 1：Zhao, X., Zhang, G., Liu, S., Chen, X., Peng, R., Dai, L., Qu, X., Li, S., Song, H., Gao, Z., Yuan, P., Liu, Z., Li, C., Shang, Z., Li, Y., Zhang, M., Qi, J., Wang, H., Du, N., Wu, Y., Bi, Y., Gao, S., Shi, Y., Yan, J., Zhang, Y., Xie*, Z., Wei*, W. and Gao*, G. F., 2019, Human neonatal Fc receptor is the cellular uncoating receptor for Enterovirus B. Cell, 177 (6): 1553-1565.e16.

Achievement 2：Niu, S., Liu, C., Liu, C., Liu, S., Song, Y., Zhang, Y., Tian, W., Zhao*, X., Wang*, P., Gao*, G. F., 2020, Molecular and structural basis of Echovirus 11 infection by using the dual-receptor system of CD55 and FcRn. Chinese Science Bulletin, 65 (1): 67-79.

Achievement 3：Chen, X., Qu, X., Liu, C., Zhang, Y., Zhang, G., Han, P., Duan, Y., Li, Q., Wang, L., Ruan, W., Wang, P., Wei, W., Gao*, G. F., Zhao*, X. and Xie*, Z., 2022, Human FcRn is a two-in-one attachment-uncoating receptor for echovirus 18. mBio, 13 (4): e0116622.

Achievement 4：Wang, Q., Yang, Q., Liu, C., Wang, G., Song, H., Shang, G., Peng, R., Qu, X., Liu, S., Cui, Y., Wang, P., Xu, W., Zhao, X., Qi, J., Yang, M. and Gao*, G. F., 2022, Molecular basis of differential receptor usage for naturally occurring CD55-binding and -nonbinding coxsackievirus B3 strains. Proceedings of the National Academy of Sciences of the United States of America, 119 (4): e2118590119.

Achievement 5：Cui, Y., Peng, R., Song, H., Tong, Z., Qu, X., Liu, S., Zhao, X., Chai, Y., Wang, P., Gao*, G. F. and Qi*, J., 2020, Molecular basis of Coxsackievirus A10 entry using the two-in-one attachment and uncoating receptor KRM1. Proceedings of the National Academy of Sciences of the United States of America, 117 (31): 18711-18718.

Achievement 6：Cui, Y., Shi, Q., Song, P., Tong, J., Cheng, Z., Zhang, H., Wang, X., Zheng, Y., Wu, Y., Wan, M., Li, S., Zhao, X., Tong, Z., Yu, Z., Gao*, S., Chen*, Y. and Gao*, G. F., 2024, Coxsackievirus A10 impairs nail regeneration and induces onychomadesis by mimicking DKK1 to attenuate Wnt signaling. Journal of Experimental Medicine, 221 (8): e20231512.

Achievement 7：Gao, S., Cui, Y., Tong, Z., Gao, G. F. ANTITUMOR VIRUS. Patent No.: 202110071113.0., 202411040437.8., PCT/7421244., PCT/CN2021/072775