title: Diagnosis and assessment of monkeypox virus (MPXV) infection by quantitative PCR assay: differentiation of Congo Basin and West African MPXV strains.
abstract: Human monkeypox, an infectious disease caused by monkeypox virus (MPXV), is endemic to western and central Africa. A LightCycler quantitative PCR (LC-qPCR) system was developed for the diagnosis of this disease, targeting the A-type inclusion body gene (ATI gene) of MPXV. One naive monkey was infected with MPXV Zr-599 (Congo Basin strain) and one with MPXV Liberia (West African strain). Another three monkeys were immunized with smallpox vaccine on 0, 3, or 7 days, respectively, before infection with MPXV Zr-599. Peripheral blood cell (PBC) and throat swab (TS) specimens were serially collected. The LC-qPCR was validated for the diagnosis of monkeypox using virus isolation. Sequencing of the partial ATI gene revealed the insertion of a unique 453-nucleotide residue in the West African strains but not in the Congo Basin strains. Specific reverse primers for Congo Basin and West African strains were designed based on the unique sequence insertion. The LC-qPCR detected the MPXV genome, but not those of the other orthopoxviruses tested nor the varicella-zoster virus. Both the sensitivity and specificity of the LC-qPCR were over 90% in comparison to virus isolation when TS specimens were tested. Fourteen of the 15 virus isolation-positive PBC specimens showed positive reactions in the assay. Further, most PBC specimens collected from symptomatic monkeys in the later stage of illness showed positive reactions in the assay but negative reaction in virus isolation. It was possible to differentiate between these two groups with the LC-qPCR. Thus, the newly developed LC-qPCR is a useful and reliable diagnostic tool for MPXV infection.
authors: Department of Virology 1, National Institute of Infectious Diseases, Tokyo 208-0011, Japan. msaijo@nih.go.jp
authors: Masayuki
authors: M
authors: Saijo
authors: Yasushi
authors: Y
authors: Ami
authors: Yuriko
authors: Y
authors: Suzaki
authors: Noriyo
authors: N
authors: Nagata
authors: Naoko
authors: N
authors: Iwata
authors: Hideki
authors: H
authors: Hasegawa
authors: Momoko
authors: M
authors: Ogata
authors: Shuetsu
authors: S
authors: Fukushi
authors: Tetsuya
authors: T
authors: Mizutani
authors: Itoe
authors: I
authors: Iizuka
authors: Koji
authors: K
authors: Sakai
authors: Tetsutaro
authors: T
authors: Sata
authors: Takeshi
authors: T
authors: Kurata
authors: Ichiro
authors: I
authors: Kurane
authors: Shigeru
authors: S
authors: Morikawa
mesh_terms: D000354:Africa, Western; D000818:Animals; D017931:DNA Primers; D015023:Democratic Republic of the Congo; D006801:Humans; D008252:Macaca fascicularis / Q000821:virology; D008297:Male; D045908:Mpox, Monkeypox / Q000175:diagnosis* / Q000821:virology; D008993:Monkeypox virus / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000592:standards
chemical_list: D017931:DNA Primers