A 30-year-old Chinese male was admitted to Queen Mary Hospital with sore throat and dysphagia when he returned to Hong Kong on 5 September, 2022. He travelled to the USA from 3 August to 25 August, 2022, to Canada from 25 August to 2 September, 2022, and to the Philippines from 2 September to 5 September, 2022. One week prior to admission, he noticed two painless penile ulcers, with subsequent appearance of rash on the face, neck, trunk, and limbs, developing from papules, vesicles then to pustules (Supplementary Fig. 1). He enjoyed good past health. On admission, the patient was afebrile, with physical examination revealing bilateral inguinal lymphadenopathy and two painless ulcers at the inner prepuce of the penis. Laboratory testing on admission showed leucocytosis (white blood cells 10.99 x 109/L) and lymphocytosis (lymphocytes 4.51 x 109/L), with atypical lymphocytes up to 26.8%, and elevated alanine transaminase (ALT 61 IU/mL), with normal renal function test. Abdominal ultrasound revealed no hepatosplenomegaly. Serological tests were negative for blood-borne viruses including hepatitis B surface antigen, hepatitis C virus antibody, and HIV antigen / antibody. Further investigations for infectious mononucleosis including Epstein-Barr virus (EBV) viral capsid antigen IgM, cytomegalovirus (CMV) IgM, and Toxoplasma IgM/IgG were all negative. Electron microscopy of the vesicular fluid showed brick-shaped virions (Supplementary Fig. 2). Multiple specimens including deep throat saliva, throat swabs, vesicle swabs, rectal swab, urine, and blood were collected, with DNA extraction using EZ1 Virus Mini Kit version 2.0 (QIAGEN, Germany). These were subjected to MPXV real-time PCR using both commercial (TIB Molbiol, Germany) and in-house assays targeting the J2L/J2R and TNF receptor gene of MPXV respectively. The diagnosis of monkeypox was confirmed by detection of MPXV DNA by PCR in all specimens, with deep throat saliva, throat swabs, and vesicle swabs showing lower cycle threshold value when compared with other clinical specimens (Table).
Further whole genome sequencing performed by nanopore sequencing showed that our strain belongs to Clade IIb; Lineage B.1.7 (Figure). It is most closely related to hMpxV/United_Kingdom/UKHSA-40/2022. Several unique nucleotide mutations were detected in our strain (compared to B.1.7 complete sequences deposited to GISAID as of 13 September 2022; numbering according to NCBI Reference Sequence: NC_063383.1), including C142797T (OPG164:S7L), C149137T (OPG174:D87N), G150706A, G186791A, C188491T, and deletion at nucleotide position 136513–136515 (OPG153:D372-).