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Sugimoto S, Kawase M, Suwa R, Kume Y, Chishiki M, Ono T, Okabe H, Norito S, Hanaki KI, Hosoya M, Hashimoto K, Shirato K. Comparison of mutations in human parainfluenza viruses during passage in primary human bronchial/tracheal epithelial air-liquid interface cultures and cell lines. Microbiol Spectr 2024:e0116424. [PMID: 39078148 DOI: 10.1128/spectrum.01164-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 05/31/2024] [Indexed: 07/31/2024] Open
Abstract
Human parainfluenza virus (HPIV) causes respiratory infections, which are exacerbated in children and older people. Correct evaluation of viral characteristics is essential for the study of countermeasures. However, adaptation of viruses to cultured cells during isolation or propagation might select laboratory passage-associated mutations that modify the characteristics of the virus. It was previously reported that adaptation of HPIV3, but not other HPIVs, was avoided in human airway epithelia. To examine the influence of laboratory passage on the genomes of HPIV1-HPIV4, we evaluated the occurrence of mutations after passage in primary human bronchial/tracheal epithelial cell air-liquid interface (HBTEC-ALI) culture and conventional cultured cells (Vero cells expressing the transmembrane protease, serine 2, and normal Vero cells). The occurrence of mutations was significantly lower in HBTEC-ALI than in conventional culture. In HBTEC-ALI culture, most of the mutations were silent or remained at low variant frequency, resulting in less impact on the viral consensus sequence. In contrast, passage in conventional culture induced or selected genetic mutations at high frequency with passage-associated unique substitutions. High mutagenesis of hemagglutinin-neuraminidase was commonly observed in all four HPIVs, and mutations even occurred in a single passage. In addition, in HPIV1 and HPIV2, mutations in the large protein were more frequent. These results indicate that passage in HBTEC-ALI culture is more suitable than conventional culture for maintaining the original characteristics of clinical isolates in all four HPIVs, which can help with the understanding of viral pathogenesis. IMPORTANCE Adaptation of viruses to cultured cells can increase the risk of misinterpretation in virological characterization of clinical isolates. In human parainfluenza virus (HPIV) 3, it has been reported that the human airway epithelial and lung organoid models are preferable for the study of viral characteristics of clinical strains without mutations. Therefore, we analyzed clinical isolates of all four HPIVs for the occurrence of mutations after five laboratory passages in human bronchial/tracheal epithelial cell air-liquid interface (HBTEC-ALI) or conventional culture. We found a high risk of hemagglutinin-neuraminidase mutagenesis in all four HPIVs in conventional cultured cells. In addition, in HPIV1 and HPIV2, mutations of the large protein were also more frequent in conventional cultured cells than in HBTEC-ALI culture. HBTEC-ALI culture was useful for maintaining the original sequence and characteristics of clinical isolates in all four HPIVs. The present study contributes to the understanding of HPIV pathogenesis and antiviral strategies.
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Affiliation(s)
- Satoko Sugimoto
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
- Research Center for Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, Japan
| | - Miyuki Kawase
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
| | - Reiko Suwa
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yohei Kume
- Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Mina Chishiki
- Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Takashi Ono
- Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Hisao Okabe
- Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Sakurako Norito
- Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Ken-Ichi Hanaki
- Research Center for Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, Japan
| | - Mitsuaki Hosoya
- Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Koichi Hashimoto
- Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Kazuya Shirato
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
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Kitai Y, Watanabe O, Ohmiya S, Kisu T, Ota R, Kawakami K, Katoh H, Fukuzawa K, Takeda M, Nishimura H. Detailed analysis of low temperature inactivation of respiratory syncytial virus. Sci Rep 2024; 14:11823. [PMID: 38783052 PMCID: PMC11116427 DOI: 10.1038/s41598-024-62658-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 05/20/2024] [Indexed: 05/25/2024] Open
Abstract
Our previous findings indicated that many respiratory syncytial virus (RSV) isolates are unstable at 4 °C compared to 20 °C. Some of the strains completely lose infectivity after 24 h at 4 °C. This study analyzed the inactivation process at 4 °C using a representative strain, RSV/Sendai/851/13. After 24 h of storage at 4 °C, the virus was completely inactivated but retained its ability to attach to and to be taken into host cells. It suggested a reduced fusion ability between the viral and cellular membranes. During storage at 4 °C, the RSV fusion (F) protein underwent a conformational change and was no longer recognized by pre-fusion form-specific antibodies. When the RSV/Sendai/851/13 strain was passaged at 4 °C, a variant with an amino acid substitution, I148T, in the F protein fusion peptide was selected. Also, an amino acid change in G protein demonstrating stability at low temperatures was obtained. These results show that the inactivation of RSV at 4 °C is due to the loss of membrane fusion activity in the F protein, which cannot maintain its pre-fusion state at 4 °C.
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Affiliation(s)
- Yuki Kitai
- Department of Microbiology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Miyagi, Japan.
| | - Oshi Watanabe
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Miyagi, Japan
| | - Suguru Ohmiya
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Miyagi, Japan
| | - Tomoko Kisu
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Miyagi, Japan
| | - Reiko Ota
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Miyagi, Japan
| | - Kazuyoshi Kawakami
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Hiroshi Katoh
- Department of Microbiology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kaori Fukuzawa
- Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka, Japan
| | - Makoto Takeda
- Department of Microbiology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Miyagi, Japan.
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3
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Kitai Y, Sato K, Shirato K, Ohmiya S, Watanabe O, Kisu T, Ota R, Takeda M, Kawakami K, Nishimura H. Variation in Thermal Stability among Respiratory Syncytial Virus Clinical Isolates under Non-Freezing Conditions. Viruses 2022; 14:v14040679. [PMID: 35458409 PMCID: PMC9029476 DOI: 10.3390/v14040679] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/23/2022] [Accepted: 03/23/2022] [Indexed: 12/10/2022] Open
Abstract
Virus isolates are not only useful for diagnosing infections, e.g., respiratory syncytial virus (RSV), but can also facilitate many aspects of practical viral studies such as analyses of antigenicity and the action mechanisms of antivirals, among others. We have been isolating RSV from clinical specimens from patients with respiratory symptoms every year since our first isolation of RSV in 1964, and isolation rates have varied considerably over the years. As collected clinical specimens are conventionally stored in a refrigerator from collection to inoculation into cells, we hypothesized that certain storage conditions or associated factors might account for these differences. Hence, we evaluated the thermal stability of a total of 64 viruses isolated from 1998 to 2018 upon storage at 4 °C and 20 °C for a defined duration. Interestingly, and contrary to our current understanding, 22 strains (34%) showed a greater loss of viability upon short-term storage at 4 °C than at 20 °C. Thirty-seven strains (57%) showed an almost equal loss, and only five strains (8%) were more stable at 4 °C than at 20 °C. This finding warrants reconsideration of the temperature for the temporary storage of clinical samples for RSV isolation.
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Affiliation(s)
- Yuki Kitai
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagino 2-11-12, Miyagino-ku, Sendai 983-8520, Japan; (Y.K.); (S.O.); (O.W.); (T.K.); (R.O.)
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, Sendai 980-0872, Japan; (K.S.); (K.K.)
| | - Ko Sato
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, Sendai 980-0872, Japan; (K.S.); (K.K.)
- Department of Intelligent Network for Infection Control, Tohoku University Graduate School of Medicine, Sendai 980-0872, Japan
| | - Kazuya Shirato
- Department of Virology III, National Institute of Infectious Disease, Tokyo 208-0011, Japan; (K.S.); (M.T.)
| | - Suguru Ohmiya
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagino 2-11-12, Miyagino-ku, Sendai 983-8520, Japan; (Y.K.); (S.O.); (O.W.); (T.K.); (R.O.)
| | - Oshi Watanabe
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagino 2-11-12, Miyagino-ku, Sendai 983-8520, Japan; (Y.K.); (S.O.); (O.W.); (T.K.); (R.O.)
| | - Tomoko Kisu
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagino 2-11-12, Miyagino-ku, Sendai 983-8520, Japan; (Y.K.); (S.O.); (O.W.); (T.K.); (R.O.)
| | - Reiko Ota
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagino 2-11-12, Miyagino-ku, Sendai 983-8520, Japan; (Y.K.); (S.O.); (O.W.); (T.K.); (R.O.)
| | - Makoto Takeda
- Department of Virology III, National Institute of Infectious Disease, Tokyo 208-0011, Japan; (K.S.); (M.T.)
| | - Kazuyoshi Kawakami
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, Sendai 980-0872, Japan; (K.S.); (K.K.)
- Department of Intelligent Network for Infection Control, Tohoku University Graduate School of Medicine, Sendai 980-0872, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Miyagino 2-11-12, Miyagino-ku, Sendai 983-8520, Japan; (Y.K.); (S.O.); (O.W.); (T.K.); (R.O.)
- Correspondence: ; Tel./Fax: +81-22-293-1173
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Shaw Stewart PD, Bach JL. Temperature dependent viral tropism: understanding viral seasonality and pathogenicity as applied to the avoidance and treatment of endemic viral respiratory illnesses. Rev Med Virol 2021; 32:e2241. [PMID: 33942417 PMCID: PMC8209954 DOI: 10.1002/rmv.2241] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 04/20/2021] [Indexed: 12/29/2022]
Abstract
This review seeks to explain three features of viral respiratory illnesses that have perplexed generations of virologists: (1) the seasonal timing of respiratory illness and the rapid response of outbreaks to weather, specifically temperature; (2) the common viruses causing respiratory illness worldwide, including year‐round disease in the Tropics; (3) the rapid arrival and termination of epidemics caused by influenza and other viruses. The inadequacy of the popular explanations of seasonality is discussed, and a simple hypothesis is proposed, called temperature dependent viral tropism (TDVT), that is compatible with the above features of respiratory illness. TDVT notes that viruses can spread more effectively if they moderate their pathogenicity (thereby maintaining host mobility) and suggests that endemic respiratory viruses accomplish this by developing thermal sensitivity within a range that supports organ‐specific viral tropism within the human body, whereby they replicate most rapidly at temperatures below body temperature. This can confine them to the upper respiratory tract and allow them to avoid infecting the lungs, heart, gut etc. Biochemical and tissue‐culture studies show that ‘wild’ respiratory viruses show such natural thermal sensitivity. The typical early autumn surge of colds and the occurrence of respiratory illness in the Tropics year‐round at intermediate levels are explained by the tendency for strains to adapt their thermal sensitivity to their local climate and season. TDVT has important practical implications for preventing and treating respiratory illness including Covid‐19. It is testable with many options for experiments to increase our understanding of viral seasonality and pathogenicity.
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Eccles R. Why is temperature sensitivity important for the success of common respiratory viruses? Rev Med Virol 2020; 31:1-8. [PMID: 32776651 PMCID: PMC7435572 DOI: 10.1002/rmv.2153] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 01/01/2023]
Abstract
This review explores the idea that temperature sensitivity is an important factor in determining the success of respiratory viruses as human parasites. The review discusses several questions. What is viral temperature sensitivity? At what range of temperatures are common respiratory viruses sensitive? What is the mechanism for their temperature sensitivity? What is the range of temperature along the human airway? What is it that makes respiratory viruses such successful parasites of the human airway? What is the role of temperature sensitivity in respiratory zoonoses? A definition of temperature sensitivity is proposed, as “the property of a virus to replicate poorly or not at all, at the normal body temperature of the host (restrictive temperature), but to replicate well at the lower temperatures found in the upper airway of the host (permissive temperature).” Temperature sensitivity may influence the success of a respiratory virus in several ways. Firstly; by restricting the infection to the upper airways and reducing the chance of systemic infection that may reduce host mobility and increase mortality, and thus limit the spread of the virus. Secondly; by causing a mild upper airway illness with a limited immune response compared to systemic infection, which means that persistent herd immunity does not develop to the same extent as with systemic infections, and re‐infection may occur later. Thirdly; infection of the upper airway triggers local reflex rhinorrhea, coughing and sneezing which aid the exit of the virus from the host and the spread of infection in the community.
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Affiliation(s)
- Ronald Eccles
- Emeritus Professor, Cardiff School of Biosciences, Cardiff University, UK
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6
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Consensus and variations in cell line specificity among human metapneumovirus strains. PLoS One 2019; 14:e0215822. [PMID: 31013314 PMCID: PMC6478314 DOI: 10.1371/journal.pone.0215822] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 04/09/2019] [Indexed: 11/30/2022] Open
Abstract
Human metapneumovirus (HMPV) has been a notable etiological agent of acute respiratory infection in humans, but it was not discovered until 2001, because HMPV replicates only in a limited number of cell lines and the cytopathic effect (CPE) is often mild. To promote the study of HMPV, several groups have generated green fluorescent protein (GFP)-expressing recombinant HMPV strains (HMPVGFP). However, the growing evidence has complicated the understanding of cell line specificity of HMPV, because it seems to vary notably among HMPV strains. In addition, unique A2b clade HMPV strains with a 180-nucleotide duplication in the G gene (HMPV A2b180nt-dup strains) have recently been detected. In this study, we re-evaluated and compared the cell line specificity of clinical isolates of HMPV strains, including the novel HMPV A2b180nt-dup strains, and six recombinant HMPVGFP strains, including the newly generated recombinant HMPV A2b180nt-dup strain, MG0256-EGFP. Our data demonstrate that VeroE6 and LLC-MK2 cells generally showed the highest infectivity with any clinical isolates and recombinant HMPVGFP strains. Other human-derived cell lines (BEAS-2B, A549, HEK293, MNT-1, and HeLa cells) showed certain levels of infectivity with HMPV, but these were significantly lower than those of VeroE6 and LLC-MK2 cells. Also, the infectivity in these suboptimal cell lines varied greatly among HMPV strains. The variations were not directly related to HMPV genotypes, cell lines used for isolation and propagation, specific genome mutations, or nucleotide duplications in the G gene. Thus, these variations in suboptimal cell lines are likely intrinsic to particular HMPV strains.
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7
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Oda K, Nishimura H, Watanabe O, Kubo T, Shindo S. A case report on parainfluenza virus type 4a infection in a 1-year-old boy with biphasic fever. J Thorac Dis 2018; 10:S2305-S2308. [PMID: 30116609 DOI: 10.21037/jtd.2018.05.159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A 1-year-old boy was infected with parainfluenza virus type 4a (PIV4a) during an influenza epidemic in January 2016. His body temperature was 38.2 °C on day 1 of the illness followed by an intermittent phase of 36.5 °C on days 2 and 3, and it rose again on day 3 and peaked at 39.6 °C on day 4, of which the fever pattern was reminiscent of an influenza case with biphasic fever. However, results of rapid influenza virus (IFV) antigen tests performed at the first clinical visit and during the second fever phase on day 4 were both negative. The PIV4a was isolated from all the nasal aspirate specimens on days 1, 4, and 7. Other common respiratory viruses were negative in all the specimens in the viral isolation trials using the multiplex cell culture system and RT-PCR tests. The fever disappeared within 5 days after the onset without any antibiotic treatment, which strongly suggested the PIV4a as the causative agent of the patient's illness. On the basis of the incubation period required for the appearance of the cytopathic effect (CPE) in the infected cells, from specimen inoculation to the cells, the viral load in the nasal cavity was speculated to be greatest on day 4. His cough started on day 1 and persisted until day 9, and the viral isolation indicated that the shedding of the active virus continued with the coughing even after the termination of fever.
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Affiliation(s)
- Keiko Oda
- Department of Health Management, College of Healthcare Management, Miyama, Japan.,Virus Research Center, Clinical Research Division, Sendai Medical Center, National Hospital Organization, Sendai, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, National Hospital Organization, Sendai, Japan
| | - Ohshi Watanabe
- Virus Research Center, Clinical Research Division, Sendai Medical Center, National Hospital Organization, Sendai, Japan
| | - Toru Kubo
- Virus Research Center, Clinical Research Division, Sendai Medical Center, National Hospital Organization, Sendai, Japan.,Nagasaki Genbaku Isahaya Hospital, Isahaya, Nagasaki, Japan.,Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Nagasaki, Japan
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Sato K, Watanabe O, Ohmiya S, Chiba F, Suzuki A, Okamoto M, Younghuang J, Hata A, Nonaka H, Kitaoka S, Nagai Y, Kawamura K, Hayashi M, Kumaki S, Suzuki T, Kawakami K, Nishimura H. Efficient isolation of human metapneumovirus using MNT-1, a human malignant melanoma cell line with early and distinct cytopathic effects. Microbiol Immunol 2017; 61:497-506. [PMID: 28940687 DOI: 10.1111/1348-0421.12542] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/23/2017] [Accepted: 09/16/2017] [Indexed: 01/30/2023]
Abstract
Isolation of human metapneumovirus (HMPV) from clinical specimens is currently inefficient because of the lack of a cell culture system in which a distinct cytopathic effect (CPE) occurs. The cell lines LLC-MK2, Vero and Vero E6 are used for isolation of HMPV; however, the CPE in these cell lines is subtle and usually requires a long observation period and sometimes blind passages. Thus, a cell line in which an early and distinct CPE occurs following HMPV inoculation is highly desired by clinical virology laboratories. In this study, it was demonstrated that, in the human malignant melanoma cell line MNT-1, obvious syncytium formation occurs shortly after inoculation with HMPV-positive clinical specimens. In addition, the growth and efficiency of isolation of HMPV were greater using MNT-1 than using any other conventional cell line. Addition of this cell line to our routine viral isolation system for clinical specimens markedly enhanced isolation frequency, allowing isolation-based surveillance. MNT-1 has the potential to facilitate clinical and epidemiological studies of HMPV.
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Affiliation(s)
- Ko Sato
- Virus Research Center, Clinical Research Division, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Japan
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Oshi Watanabe
- Virus Research Center, Clinical Research Division, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Japan
| | - Suguru Ohmiya
- Virus Research Center, Clinical Research Division, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Japan
| | - Fumiko Chiba
- Virus Research Center, Clinical Research Division, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Japan
| | - Akira Suzuki
- Virus Research Center, Clinical Research Division, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Japan
| | - Michiko Okamoto
- Virus Research Center, Clinical Research Division, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Japan
| | - Jiang Younghuang
- Tauns Laboratories, 761-1 Kamishima, Izunokuni, Shizuoka 410-2325, Japan
| | - Akihiro Hata
- Tauns Laboratories, 761-1 Kamishima, Izunokuni, Shizuoka 410-2325, Japan
| | - Hiroyuki Nonaka
- Tauns Laboratories, 761-1 Kamishima, Izunokuni, Shizuoka 410-2325, Japan
| | - Setsuko Kitaoka
- Department of Pediatrics, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Sendai 983-8520, Japan
| | - Yukio Nagai
- Nagai Pediatric Clinic, 1-25-10 Miyagino, Miyagino-ku, Sendai, 983-0045, Japan
| | - Kazuhisa Kawamura
- Kawamura Children's Clinic, 1-16-1 Takamatsu, Aoba-ku, Sendai 981-0907, Japan
| | - Masahiro Hayashi
- Department of Dermatology, Faculty of Medicine, Yamagata University, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan
| | - Satoru Kumaki
- Department of Pediatrics, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Sendai 983-8520, Japan
| | - Tamio Suzuki
- Department of Dermatology, Faculty of Medicine, Yamagata University, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan
| | - Kazuyoshi Kawakami
- Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, 2-8-8 Miyagino, Miyagino-ku, Japan
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