Isolation and Characterization of Monkeypox Virus from the First Case of Monkeypox - Chongqing Municipality, China, 2022

Baoying Huang; Hua Zhao; Jingdong Song; Li Zhao; Yao Deng; Wen Wang; Roujian Lu; Wenling Wang; Jiao Ren; Fei Ye; Houwen Tian; Guizhen Wu; Hua Ling; Wenjie Tan

doi:10.46234/ccdcw2022.206

Isolation and Characterization of Monkeypox Virus from the First Case of Monkeypox - Chongqing Municipality, China, 2022

China CDC Wkly. 2022 Nov 18;4(46):1019-1024. doi: 10.46234/ccdcw2022.206.

Authors

Baoying Huang¹, Hua Zhao², Jingdong Song¹, Li Zhao¹, Yao Deng¹, Wen Wang¹, Roujian Lu¹, Wenling Wang¹, Jiao Ren¹, Fei Ye¹, Houwen Tian¹, Guizhen Wu¹, Hua Ling², Wenjie Tan¹

Affiliations

¹ Key Laboratory of Biosafety, National Health and Family Planning Commission, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing Municipality, China.
² Chongqing Center for Disease Control and Prevention, Chongqing Municipal Key Laboratory for High Pathogenic Microbes, Chongqing Municipality, China.

Abstract

Introduction: The first imported case of monkeypox (MPX) from the mainland of China was reported in September 2022. Herein, the study reports the isolation and characterization of MPX virus (MPXV) in this case.

Methods: Clinical specimens including skin blister fluid, oropharyngeal and nasopharyngeal swabs, and blood were collected and inoculated onto Vero cells. The isolated virus was identified as MPXV using quantitative polymerase chain reaction (qPCR), cytopathic effects (CPEs), immunofluorescence assay (IFA) and transmission electron microscopy (TEM). Plaque assays were employed to quantify infectious plaque-forming units (PFUs). The plaque reduction neutralization test (PRNT) was developed to determine the neutralizing antibody (nAb) against MPXV.

Results: MPXV replication was confirmed with qPCR. Typical CPEs were observed 48 h post-incubation. The isolated virus was named MPXV-B.1-China-C-Tan-CQ01. IFA showed that MPXV reacted with serum of MPX case. Orthopoxvirus morphology was observed using TEM. The virus titer increased to >10⁶ PFU/mL after three passages. The serum PRNT 50% neutralization titer (NT₅₀) was 35 for the MPX patient 6 days after symptom onset.

Discussion: The study successfully isolated the first MPXV strain in the mainland of China, MPXV-B.1-China-C-Tan-CQ01. Infectious titration and PRNT methods have been developed. The study provides key resources and technical platforms for further research as well as anti-viral drug and vaccine development against MPX.

Keywords: Monkeypox virus; Plaque assays; Plaque reduction neutralization test; Virus isolation.

Copyright and License information: Editorial Office of CCDCW, Chinese Center for Disease Control and Prevention 2022.

Grants and funding

Supported by the National Key Research and Development Program of China (2022YFC2304100, 2022YFC2303401, 2021YFA1201003, 2016YFD0500301, 2020YFC0840900, 2021YFC0863300) and the Beijing Science and Technology Plan (Z211100002521017, Z211100002521015)