MMF inhibits poxvirus infection by disrupting IMPDH2 interaction with USP5 and inducing its rod-and-ring assemblies

Qian Sun; Kesen Liu; Wandi Cao; Chengyue Wu; Hanhua Zhang; Xingya Wang; Chen Peng; Jie Sun; Anbing Zhang; Zhuo Zhou; Xing Liu

doi:10.1016/j.virs.2026.07.009

August 2026

. doi: 10.1016/j.virs.2026.07.009

Citation: Qian Sun, Kesen Liu, Wandi Cao, Chengyue Wu, Hanhua Zhang, Xingya Wang, Chen Peng, Jie Sun, Anbing Zhang, Zhuo Zhou, Xing Liu. MMF inhibits poxvirus infection by disrupting IMPDH2 interaction with USP5 and inducing its rod-and-ring assemblies .VIROLOGICA SINICA, 2026, 41(4) : 923-936. http://dx.doi.org/10.1016/j.virs.2026.07.009

MMF通过干扰IMPDH2与USP5结合并诱导IMPDH2“R&R”结构的组装抑制痘病毒复制

孙倩 ^a ,
刘克森 ^b ,
曹万迪 ^b ,
吴承月 ^b ,
张汉华 ^b ,
王兴娅 ^b ,
彭辰 ^c ,
孙洁 ^d ,
张安兵 ^e,, ,
周卓 ^f,, ,
刘星 ^b,,

a 深圳大学医学部药学院, 深圳, 518060, 中国;
b 广东省感染免疫与炎症重点实验室; "一带一路"深圳一阿拉木图医学前沿联合实验室; 病原生物学系, 基础医学院, 深圳大学医学部, 深圳, 518060, 中国;
c 中国农业大学兽医学院兽医公共卫生国家重点实验室, 北京, 100193, 中国;
d 中国广东深圳海关动植物检验检疫技术中心, 深圳, 518026, 中国;
e 中国中山市中山人民医院呼吸与危重症医学科, 中山, 528403, 中国;
f 重大疾病共同机制研究国家重点实验室, 苏州系统医学研究所, 中国医学科学院&北京协和医学院, 苏州, 215128, 中国

通讯作者： 张安兵, zhongshanzab@126.com; 周卓, zhouzhuo@cams.cn; 刘星, xingliu1@szu.edu.cn
收稿日期： 2026-06-23
录用日期： 2026-07-17

摘要

猴痘病毒(MPXV)作为一种高致病性正痘病毒，已引发全球性疫情，构成严重的公共卫生威胁。目前，用于治疗天花的抗病毒药物虽已被应用于猴痘感染的临床干预，但其应用受到药物储备有限及耐药株出现等因素的制约。病毒通过重塑宿主核苷酸代谢网络，获取复制与传播所必需的生物合成前体，该机制已成为开发广谱抗病毒药物的重要靶向策略。本研究利用痘苗病毒(VACV)与猴痘病毒在遗传和生物学特性上的高度相似性，以VACV为替代模型，系统筛选了10种美国FDA批准的靶向核苷酸代谢酶的抑制剂，以期发现新型猴痘病毒抑制候选药物。结果显示，吗替麦考酚酯(MMF)-一种肌苷酸5'-脱氢酶Ⅱ型(IMPDH2)抑制剂，对VACV和MPXV均表现出显著的抗病毒活性。进一步的药物作用时相分析表明，MMF主要干预病毒的复制阶段。机制研究揭示，MMF可阻断泛素特异性蛋白酶5(USP5)介导的IMPDH2去泛素化过程，并且能诱导细胞中出现“rod-and-ring”(R&R)结构，进而抑制IMPDH2功能，降低细胞内dNTP池水平，最终有效抑制猴痘病毒的复制。综上所述，本研究证实MMF是一种高效的抗痘苗病毒及猴痘病毒药物，同时建立了一种以宿主因子为靶点的抗病毒治疗策略，为应对未来猴痘疫情暴发提供了新的干预思路。
- 吗替麦考酚酯
- , 肌苷酸5'-脱氢酶Ⅱ
- , 泛素特异性蛋白酶5
- , 杆/环结构
- , 痘苗病毒
- , 猴痘病毒

MMF inhibits poxvirus infection by disrupting IMPDH2 interaction with USP5 and inducing its rod-and-ring assemblies

Qian Sun ^a ,
Kesen Liu ^b ,
Wandi Cao ^b ,
Chengyue Wu ^b ,
Hanhua Zhang ^b ,
Xingya Wang ^b ,
Chen Peng ^c ,
Jie Sun ^d ,
Anbing Zhang ^e,, ,
Zhuo Zhou ^f,, ,
Xing Liu ^b,,

a. School of Pharmaceutical Sciences, Shenzhen University Medical School, Shenzhen 518060, China;
b. Guangdong Provincial Key Laboratory of Infection Immunity and Inflammation, The Belt & Road Shenzhen-Almaty Joint Laboratory for Frontiers of Medical Science (B&RsalFMS), Department of Pathogen Biology, School of Basic Medical Sciences, Shenzhen University Medical School, Shenzhen 518060, China;
c. National Key Laboratory of Veterinary Public Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
d. Shenzhen Customs Animal and Plant Inspection and Quarantine Technology Centre, Shenzhen 518026, China;
e. Department of Pulmonary and Critical Care Medicine, Zhongshan City People's Hospital, Zhongshan 528403, China;
f. State Key Laboratory of Common Mechanism Research for Major Diseases, Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou 215128, China

Corresponding author: Anbing Zhang, zhongshanzab@126.com Zhuo Zhou, zhouzhuo@cams.cn Xing Liu, xingliu1@szu.edu.cn
Received Date: 23 June 2026
Accepted Date: 17 July 2026

Abstract

Monkeypox virus (MPXV), a pathogenic orthopoxvirus, has caused major outbreaks and emerged as a global public health threat. Although antivirals approved for smallpox are used therapeutically against monkeypox, their clinical utility is limited by drug availability and emerging resistance. The conserved strategy by which viruses remodel host nucleotide metabolism to secure biosynthetic precursors for replication and spread has emerged as a pivotal target for the development of broad-spectrum antiviral therapeutics. In this study, leveraging the high genetic and biological similarity between vaccinia virus (VACV) and MPXV, we employed VACV as a surrogate model to screen 10 FDA-approved inhibitors targeting nucleotide metabolism enzymes, aiming to identify potential novel inhibitors against MPXV. Mycophenolate mofetil (MMF), an inosine 5'-monophosphate dehydrogenase type II (IMPDH2) inhibitor, displayed potent inhibition effects against both VACV and MPXV. Subsequent downstream time-course studies revealed that MMF targets a post-entry stage of the viral replication cycle. Mechanistic studies suggest that MMF inhibits IMPDH2 activity by suppressing ubiquitin-specific protease 5 (USP5)-mediated deubiquitination of IMPDH2 and inducing rod-and-ring (R&R) assembly, leading to reducing dNTP pools and enhancing antiviral effects. In conclusion, our findings demonstrate that MMF is an effective antiviral drug against VACV and MPXV infection and establish a host-directed therapeutic strategy to combat future orthopoxvirus outbreaks.
- Mycophenolate mofetil (MMF)
- , IMPDH2
- , Ubiquitin-specific protease 5 (USP5)
- , Rod/ring structures
- , Vaccinia virus
- , Monkeypox virus (MPXV)

References
1. Alakunle, E., Kolawole, D., Diaz-Canova, D., Alele, F., Adegboye, O., Moens, U., Okeke, M.I., 2024. A comprehensive review of monkeypox virus and mpox characteristics. Front Cell Infect Microbiol 14, 1360586.
2. Alakunle, E., Moens, U., Nchinda, G., Okeke, M.I., 2020. Monkeypox Virus in Nigeria: Infection Biology, Epidemiology, and Evolution. Viruses 12, 1257.
3. Allison, A.C., 2005. Mechanisms of action of mycophenolate mofetil. Lupus 14 Suppl 1, s2-8.
4. Andrei, G., Snoeck, R., 2023. Differences in pathogenicity among the mpox virus clades: impact on drug discovery and vaccine development. Trends Pharmacol Sci 44, 719-739.
5. Andrei, G., Snoeck, R., 2023. Differences in pathogenicity among the mpox virus clades: impact on drug discovery and vaccine development. Trends Pharmacol Sci 44, 719-739.
6. Burrell, A.L., Kollman, J.M., 2022. IMPDH dysregulation in disease: a mini review. Biochem Soc Trans 50, 71-82.
7. Calise, S.J., Chan, E.K.L., 2020. Anti-rods/rings autoantibody and IMPDH filaments: an update after fifteen years of discovery. Autoimmun Rev 19, 102643.
8. Carcamo, W.C., Satoh, M., Kasahara, H., Terada, N., Hamazaki, T., Chan, J.Y., Yao, B., Tamayo, S., Covini, G., von Muhlen, C.A., Chan, E.K., 2011. Induction of cytoplasmic rods and rings structures by inhibition of the CTP and GTP synthetic pathway in mammalian cells. PLoS One 6, e29690.
9. Castaneda Catana, M.A., Rivas Marquina, A.P., Dodes Traian, M.M., Carlucci, M.J., Damonte, E.B., Perez, O.E., Arrua, E.C., Sepulveda, C.S., 2025. Bovine Serum Albumin Nanoparticle-Mediated Delivery of Ribavirin and Mycophenolic Acid for Enhanced Antiviral Therapeutics. Viruses 17, 138.
10. Chen, C.Y., Chen, C.L., Ng, Y.S., Lee, D.Y., Lin, S.S., Huang, C.K., Kumar, R., Wang, H.C., 2025. Glucose- and glutamine-driven de novo nucleotide synthesis facilitates WSSV replication in shrimp. Cell Commun Signal 23, 191.
11. Cho, J., Yi, H., Jang, E.Y., Lee, M.S., Lee, J.Y., Kang, C., Lee, C.H., Kim, K., 2017. Mycophenolic mofetil, an alternative antiviral and immunomodulator for the highly pathogenic avian influenza H5N1 virus infection. Biochem Biophys Res Commun 494, 298-304.
12. Dsouza, L., Pant, A., Offei, S., Priyamvada, L., Pope, B., Satheshkumar, P.S., Wang, Z., Yang, Z., 2023. Antiviral activities of two nucleos(t)ide analogs against vaccinia, mpox, and cowpox viruses in primary human fibroblasts. Antiviral Res 216, 105651.
13. Dsouza, L., Yang, Z., 2025. Viral Reprogramming of Nucleotide Synthesis and Its Impact on Viral Infection. J Med Virol 97, e70563.
14. Frenois-Veyrat, G., Gallardo, F., Gorge, O., Marcheteau, E., Ferraris, O., Baidaliuk, A., Favier, A.L., Enfroy, C., Holy, X., Lourenco, J., Khoury, R., Nolent, F., Grosenbach, D.W., Hruby, D.E., Ferrier, A., Iseni, F., Simon-Loriere, E., Tournier, J.N., 2022. Tecovirimat is effective against human monkeypox virus in vitro at nanomolar concentrations. Nat Microbiol 7, 1951-1955.
15. Gedeon, A., Ayoub, N., Brule, S., Raynal, B., Karimova, G., Gelin, M., Mechaly, A., Haouz, A., Labesse, G., Munier-Lehmann, H., 2023. Insight into the role of the Bateman domain at the molecular and physiological levels through engineered IMP dehydrogenases. Protein Sci 32, e4703.
16. Harapan, H., Ophinni, Y., Megawati, D., Frediansyah, A., Mamada, S.S., Salampe, M., Bin Emran, T., Winardi, W., Fathima, R., Sirinam, S., Sittikul, P., Stoian, A.M., Nainu, F., Sallam, M., 2022. Monkeypox: A Comprehensive Review. Viruses 14, 2155.
17. Hart, B.J., Dyall, J., Postnikova, E., Zhou, H., Kindrachuk, J., Johnson, R.F., Olinger, G.G., Frieman, M.B., Holbrook, M.R., Jahrling, P.B., Hensley, L., 2014. Interferon-β and mycophenolic acid are potent inhibitors of Middle East respiratory syndrome coronavirus in cell-based assays. J Gen Virol 95, 571-577.
18. Hisam, F., Winn, E., Mukherjee, S., Price, S., Gaspar, Y.A., Wang, C., Baniasadi, H.R., Delgado, T., Sanchez, E.L., 2026. Global Metabolomic Analysis of Lytic KSHV Infection: Induced Host Nucleotide Metabolism is Required for Infectious Virus Production. bioRxiv. doi:10.64898/2026.02.02.703314.
19. Hu, H., Wang, Q., Ai, Q., Zhou, P., He, Y., Ye, Z., Ma, K., Zhou, M., Huang, S., Wang, L., Qi, N., Xiao, G., Wang, S., 2026. FDA-approved IMPDH inhibitors synergize with ribavirin to inhibit respiratory syncytial virus by interfering with purine de novo synthesis. Emerg Microbes Infect 15, 2640289.
20. Jiang, S., Jiang, L., Xu, Y., Ma, Y., Deng, Y., Jiao, C., Yin, M., Qin, C., Li, J., Zhang, L., Chen, S., 2025. USP5 deubiquitinates and stabilizes IMPDH2, to promote hepatocellular carcinoma progression. Oncogene 44, 1936-1948.
21. Ju, B., Liu, C., Zhang, J., Li, Y., Yang, H., Zhou, B., Huang, B., Ma, J., Lu, J., Cheng, L., Cong, Z., Zhu, L., Shi, T., Sun, Y., Li, N., Chen, T., Wang, M., Tang, S., Ge, X., Zhao, J., Tan, W.J., Yan, R., Xue, J., Zhang, Z., 2025. Structurally conserved human anti-A35 antibodies protect mice and macaques from mpox virus infection. Cell 188, 6253-6265.e6214.
22. Keppeke, G.D., Calise, S.J., Chan, E.K.L., Andrade, L.E.C., 2019. Ribavirin induces widespread accumulation of IMP dehydrogenase into rods/rings structures in multiple major mouse organs. Antiviral Res 162, 130-135.
23. Li, H., Huang, Q.Z., Zhang, H., Liu, Z.X., Chen, X.H., Ye, L.L., Luo, Y., 2023. The land-scape of immune response to monkeypox virus. EBioMedicine 87, 104424.
24. Lim, C.K., Roberts, J., Moso, M., Liew, K.C., Taouk, M.L., Williams, E., Tran, T., Steinig, E., Caly, L., Williamson, D.A., 2023. Mpox diagnostics: Review of current and emerging technologies. J Med Virol 95, e28429.
25. Luo, P., Liu, D., Zhang, Q., Yang, F., Wong, Y.K., Xia, F., Zhang, J., Chen, J., Tian, Y., Yang, C., Dai, L., Shen, H.M., Wang, J., 2022. Celastrol induces ferroptosis in activated HSCs to ameliorate hepatic fibrosis via targeting peroxiredoxins and HO-1. Acta Pharm Sin B 12, 2300-2314.
26. MacIntyre, C.R., de Sousa, J.C., Heininger, U., Kardos, P., Konstantopoulos, A., Middleton, D., Nolan, T., Papi, A., Rendon, A., Rizzo, A., Sampson, K., Sette, A., Sobczyk, E., Tan, T., Weil-Olivier, C., Weinberger, B., Wilkinson, T., von Konig, C.H.W., 2024. Public health management of pertussis in adults: Practical challenges and future strategies. Hum Vaccin Immunother 20, 2377904.
27. Manchala, N.R., Dungdung, R., Trivedi, P., Unniyampurath, U., Pilankatta, R., 2019. Mycophenolic acid (MPA) modulates host cellular autophagy progression in sub genomic dengue virus-2 replicon cells. Microb Pathog 137, 103762.
28. Mitja, O., Ogoina, D., Titanji, B.K., Galvan, C., Muyembe, J.J., Marks, M., Orkin, C.M., 2023. Monkeypox. Lancet 401, 60-74.
29. Nass, K., Redecke, L., Perbandt, M., Yefanov, O., Klinge, M., Koopmann, R., Stellato, F., Gabdulkhakov, A., Schonherr, R., Rehders, D., Lahey-Rudolph, J.M., Aquila, A., Barty, A., Basu, S., Doak, R.B., Duden, R., Frank, M., Fromme, R., Kassemeyer, S., Katona, G., Kirian, R., Liu, H., Majoul, I., Martin-Garcia, J.M., Messerschmidt, M., Shoeman, R.L., Weierstall, U., Westenhoff, S., White, T.A., Williams, G.J., Yoon, C.H., Zatsepin, N., Fromme, P., Duszenko, M., Chapman, H.N., Betzel, C., 2020. In cellulo crystallization of Trypanosoma brucei IMP dehydrogenase enables the identification of genuine co-factors. Nat Commun 11, 620.
30. Nuzzo, J.B., Borio, L.L., Gostin, L.O., 2022. The WHO Declaration of Monkeypox as a Global Public Health Emergency. Jama 328, 615-617.
31. Ogawa-Iio, A., Takeuchi, K., Shigemi, K., Genoveso, M.J., Niitsu, H., Koh, I., Ota, Y., Yamane, K., Hinoi, T., Osaka, N., Oshima, M., Ishikawa, T., Mizuno, T., Natsumeda, M., Tateishi, K., Hashizume, R., Osuka, S., Goyama, S., Yasuda, T., Senda, T., Sasaki, A.T., 2025. IMPDH and GTP Metabolism in Cancer: Mechanisms, Regulation, and Translational Scope. Cancer Sci 116, 3250-3265.
32. Ortiz-Saavedra, B., Leon-Figueroa, D.A., Montes-Madariaga, E.S., Ricardo-Martinez, A., Alva, N., Cabanillas-Ramirez, C., Barboza, J.J., Siddiq, A., Coaguila Cusicanqui, L.A., Bonilla-Aldana, D.K., Rodriguez-Morales, A.J., 2022. Antiviral Treatment against Monkeypox: A Scoping Review. Trop Med Infect Dis 7, 369.
33. Poland, G.A., Kennedy, R.B., Tosh, P.K., 2022. Prevention of monkeypox with vaccines: a rapid review. Lancet Infect Dis 22, e349-e358.
34. Qiao, Z., Li, D., Zhang, F., Zhu, J., Liu, S., Bai, X., Yao, H., Chen, Z., Yan, Y., Xu, X., Ma, F., 2025. USP5 inhibits anti-RNA viral innate immunity by deconjugating K48-linked unanchored and K63-linked anchored ubiquitin on IRF3. PLoS Pathog 21, e1012843.
35. Rizk, Y., Lippi, G., Henry, B.M., Notarte, K.I., Rizk, J.G., 2025. Update on Mpox Management: Epidemiology, Vaccines and Therapeutics, and Regulatory Changes. Drugs 85, 1-9.
36. Shand, E.L., Sweeney, K., Sundling, K.E., McClean, M.N., Brow, D.A., 2024. Live-cell analysis of IMPDH protein levels during yeast colony growth provides insights into the regulation of GTP synthesis. mBio 15, e0102124.
37. Shchelkunova, G.A., Shchelkunov, S.N., 2022. Smallpox, Monkeypox and Other Human Orthopoxvirus Infections. Viruses 15, 103.
38. Shen, Y., Li, Y., Yan, R., 2024. Structural basis for the inhibition mechanism of the DNA polymerase holoenzyme from mpox virus. Structure 32, 654-661.e653.
39. Siegrist, E.A., Sassine, J., 2023. Antivirals With Activity Against Mpox: A Clinically Oriented Review. Clin Infect Dis 76, 155-164.
40. Smith, T.G., Gigante, C.M., Wynn, N.T., Matheny, A., Davidson, W., Yang, Y., Condori, R.E., O'Connell, K., Kovar, L., Williams, T.L., Yu, Y.C., Petersen, B.W., Baird, N., Lowe, D., Li, Y., Satheshkumar, P.S., Hutson, C.L., 2023. Tecovirimat Resistance in Mpox Patients, United States, 2022-2023. Emerg Infect Dis 29, 2426-2432.
41. Tang, N., Chen, P., Zhao, C., Liu, P., Tan, L., Song, C., Qiu, X., Liao, Y., Liu, X., Luo, T., Sun, Y., Ding, C., 2023. Newcastle Disease Virus Manipulates Mitochondrial MTHFD2-Mediated Nucleotide Metabolism for Virus Replication. J Virol 97, e0001623.
42. Tu, Y., Tan, L., Tao, H., Li, Y., Liu, H., 2023. CETSA and thermal proteome profiling strategies for target identification and drug discovery of natural products. Phytomedicine 116, 154862.
43. Vernuccio, R., Martinez Leon, A., Poojari, C.S., Buchrieser, J., Selverian, C.N., Jaleta, Y., Meola, A., Guivel-Benhassine, F., Porrot, F., Haouz, A., Chevreuil, M., Raynal, B., Mercer, J., Simon-Loriere, E., Chandran, K., Schwartz, O., Hub, J.S., Guardado-Calvo, P., 2025. Structural insights into tecovirimat antiviral activity and poxvirus resistance. Nat Microbiol 10, 734-748.
44. Wan, Q., Tavakoli, L., Wang, T.Y., Tucker, A.J., Zhou, R., Liu, Q., Feng, S., Choi, D., He, Z., Gack, M.U., Zhao, J., 2024. Hijacking of nucleotide biosynthesis and deamidation-mediated glycolysis by an oncogenic herpesvirus. Nat Commun 15, 1442.
45. Wu, M., Wang, K., Wang, H., Yan, H., Wu, S., Yang, G., Li, Y., Che, Y., Jiang, J., 2025. Mycophenolate mofetil exerts broad-spectrum antiviral activity against coronaviruses including SARS-CoV-2. Virol J 22, 56.
46. Yuan, L., Wang, M., Zhang, X., Wang, Z., 2017. Effects of protease and non-starch polysaccharide enzyme on performance, digestive function, activity and gene expression of endogenous enzyme of broilers. PLoS One 12, e0173941.
47. Zhou, S., Zhao, H., Zhu, J., Zhou, Y., Yang, Z., Wang, Z., 2026. Porcine epidemic diarrhea virus manipulates IMPDH-dependent nucleotide biosynthesis to facilitate replication. J Virol 100, e0173625.
48. Zhu, J., Gao, X., Li, Y., Zhang, Z., Xie, S., Ren, S., Li, Y., Li, H., Niu, K., Fu, S., Deng, Y., Li, Y., Moss, B., Wu, W., Peng, C., 2023. Human FAM111A inhibits vaccinia virus replication by degrading viral protein I3 and is antagonized by poxvirus host range factor SPI-1. Proc Natl Acad Sci U S A 120, e2304242120.
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