Laboratories

HIV and AIDS (Partnership field）

KEYWORDS

  • HIV
  • AIDS
  • Infectious diseases
  • Viruses
  • Drug resistance
  • Antiretroviral drugs
  • Opportunistic infections
  • Testing systems

HEAD

IMAHASHI Mayumi

Adjunct Associate Professor

CONTACT

Email imahashi.mayumi.dp◎mail.hosp.go.jp (Please send a message after replacing "◎" mark with "@" mark. )
HP Department of Infectious Diseases and Immunology | Clinical Research Center

OUTLINE

Our laboratory is dedicated to overcoming Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) and contributing to global public health. The development of antiretroviral therapies has been actively pursued, and the prognosis of people living with HIV (PLWH) has greatly improved. However, current treatments can suppress viral replication but do not achieve a cure. Moreover, no preventive vaccine has yet been developed, and many research challenges remain in the field of HIV infection.
To address these challenges, our laboratory focuses on understanding the pathogenesis of HIV infection and linking this knowledge to both “treatment” and “prevention.” Specifically, we conduct research on host defense mechanisms such as intracellular restriction factors, the mechanisms by which HIV evades antiretroviral therapy (drug resistance), and the establishment of HIV testing systems.

RESEARCH PROJECTS

1. Epidemiological Surveillance of Drug-Resistant HIV and Basic Research on Resistance Mechanisms

We conduct molecular epidemiological and information analysis studies on HIV and HIV-related viruses (see figure). Newly diagnosed HIV/AIDS cases and previously treated cases collected from hospitals and clinics are subjected to drug resistance testing, tropism assays, and subtype analysis. These data provide clinicians with essential information for selecting the most appropriate antiretroviral drugs.
Our epidemiological studies are carried out in collaboration with overseas research institutions, adopting a global perspective. Furthermore, by elucidating the molecular mechanisms underlying the emergence of HIV drug resistance to existing therapies, we aim to propose strategies for improving current drugs through basic research.
Figure: Trends in transmitted drug resistance mutations among newly diagnosed HIV/AIDS cases in Japan. The prevalence of transmitted drug resistance mutations has remained around 8–9%.

aids_project1_eng.gif

2. Epidemiological and Clinical Studies of HIV-2/AIDS

HIV-2 infection is extremely rare in Japan. Unlike HIV-1, which has caused a global pandemic, HIV-2 is localized mainly in West Africa and India. Reports indicate that HIV-2 infection may not always progress to AIDS, and in some cases, the virus is undetectable in blood samples, making diagnosis and testing more difficult.
Our laboratory is working to improve HIV-2 diagnostic technologies and to develop nationwide testing systems for monitoring HIV-2. Since standardized methods for measuring HIV-2 viral load are not yet established in Japan, we have developed our own assays for viral load and drug resistance testing, and are conducting applied research in this area.

3. Establishment of HIV Testing Systems

Japan has not yet achieved the “first 95” of the HIV care cascade, meaning that 95% of people living with HIV know their infection status. Approximately 30% of newly diagnosed patients are identified only after developing AIDS, which is a relatively high proportion compared to other developed countries. This suggests delays in testing systems.
To promote early detection, our department collaborates with government agencies, local educational institutions, and community-based organizations (CBOs) to organize three annual event-based testing campaigns and to operate permanent in-hospital testing facilities. In addition, we have compiled feedback from testing staff and launched a dedicated website for HIV testing practitioners (http://www.doitesting.info).

BIBLIOGRAPHY

2025
  1. Yokomaku Y, Noda T, Imahashi M, Nishioka Y, Myojin T, Iwamoto A, Imamura T: Antiretroviral therapies and status of people living with HIV in Japan: An update from hospital survey and national database. PLoS One 2025, 20(1):e0317655.
  2. Kidiga M, Murata M, Grover P, Ode H, Iwatani Y, Seki Y, Kuramitsu M, Morimoto M, Natsume T, Kaneko A et al: Identification of Occult Simian T-Cell Leukemia Virus Type 1 Infection in Japanese Macaques. J Infect Dis 2025, 232(2):510-518.
  3. Iwatani Y, Matsuoka K, Ode H, Kubota M, Nakata Y, Setoyama Y, Kojima K, Imahashi M, Yokomaku Y: The unique structure of the highly conserved PPLP region in HIV-1 Vif is critical for the formation of APOBEC3 recognition interfaces. mBio 2025, 16(3):e0333224.
  4. Hill AO, Kaneko N, Amos N, Bourne A, Imahashi M, Armstrong G, Gilmour S: High suicidality rates among LGB+ youth in Japan: Demographic and psychosocial correlates. J Affect Disord 2025, 387:119468.
  5. Grover P, Murata M, Kidiga M, Hayashi S, Ode H, Iwatani Y, Morimoto M, Natsume T, Kaneko A, Yasunaga JI et al: Identification of Natural Remission of Mother-to-Child Retroviral Transmission. J Infect Dis 2025, 232(1):203-211.
  6. Adachi E, Minami R, Shirano M, Nakamura H, Fukushima K, Imahashi M, Sekiya R, Yoshino Y, Taniguchi T, Team JHRCD: Evaluation of cabotegravir plus rilpivirine in routine clinical settings in Japan: A multicentre study of efficacy, safety and biomarker dynamics. HIV Med 2025, 26(11):1673-1683.
2024
  1. Ode H, Matsuda M, Shigemi U, Mori M, Yamamura Y, Nakata Y, Okazaki R, Kubota M, Setoyama Y, Imahashi M et al: Population-based nanopore sequencing of the HIV-1 pangenome to identify drug resistance mutations. Sci Rep 2024, 14(1):12099.
2023
  1. Uno S, Gatanaga H, Hayashida T, Imahashi M, Minami R, Koga M, Samukawa S, Watanabe D, Fujii T, Tateyama M et al: Virological outcomes of various first-line ART regimens in patients harbouring HIV-1 E157Q integrase polymorphism: a multicentre retrospective study. J Antimicrob Chemother 2023, 78(12):2859-2868.
  2. Otani M, Shiino T, Hachiya A, Gatanaga H, Watanabe D, Minami R, Nishizawa M, Teshima T, Yoshida S, Ito T et al: Association of demographics, HCV co-infection, HIV-1 subtypes and genetic clustering with late HIV diagnosis: a retrospective analysis from the Japanese Drug Resistance HIV-1 Surveillance Network. J Int AIDS Soc 2023, 26(5):e26086.
  3. Nakata Y, Ode H, Kubota M, Kasahara T, Matsuoka K, Sugimoto A, Imahashi M, Yokomaku Y, Iwatani Y: Cellular APOBEC3A deaminase drives mutations in the SARS-CoV-2 genome. Nucleic Acids Res 2023, 51(2):783-795.
  4. Mizuki K, Ishimaru T, Imahashi M, Ikushima Y, Takahashi H, Masuda M, Yokomaku Y: Workplace factors associated with willingness to undergo human immunodeficiency virus testing during workplace health checkups. Environ Health Prev Med 2023, 28:52.
  5. Masuda M, Ikushima Y, Ishimaru T, Imahashi M, Takahashi H, Yokomaku Y: [Current Issues of Laws Concerning HIV/AIDS Control in the Workplace]. Sangyo Eiseigaku Zasshi 2023, 65(6):366-369.
  6. Komori M, Nogimori T, Morey AL, Sekida T, Ishimoto K, Hassett MR, Masuta Y, Ode H, Tamura T, Suzuki R et al: saRNA vaccine expressing membrane-anchored RBD elicits broad and durable immunity against SARS-CoV-2 variants of concern. Nat Commun 2023, 14(1):2810.
  7. Akahata W, Sekida T, Nogimori T, Ode H, Tamura T, Kono K, Kazami Y, Washizaki A, Masuta Y, Suzuki R et al: Safety and immunogenicity of SARS-CoV-2 self-amplifying RNA vaccine expressing an anchored RBD: A randomized, observer-blind phase 1 study. Cell Rep Med 2023, 4(8):101134.

MESSAGE

HIV and AIDS (Partnership field）, Graduate School of Medicine, Nagoya University, operates as a collaborative graduate program. We are recruiting graduate students and research fellows who are interested in HIV/AIDS (epidemiology and clinical research) as well as other related viral infections. In particular, our program provides an environment where students can engage in clinical practice for HIV infection while simultaneously pursuing research questions that arise directly from the clinical setting. This collaborative program is located within the Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center. For further details, please visit our laboratory homepage: https://nagoya.hosp.go.jp/crc/departments/infectious_diseases/.

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