Lumpy Skin Disease (LSD) is a viral disease affecting cattle and water buffaloes, caused by Lumpy Skin Disease Virus (LSDV). Infected animals typically develop numerous sikn nodules across the body, along with clinical signs such as fever, decreased milk production, and abortion. The nodular skin lesions and necrotic, detached tissues (sit-fast) contain high concentrations of the virus and, due to the virus’s high environmental stability, serve as important sources of horizontal transmission. However, LSDV transmission is primarily mediated by blood-feeding arthropod vectors such as biting midges, stable flies, and ticks. Therefore, vector control measures are essential for preventing the incursion of LSD into farms. Live attenuated vaccines are effective and is widely used for the prevention of the disease; however, in many affected countries the disease has not been eradicated. In Asia, since the first outbreak in China in 2019, LSD has continued to spread in Southeast and East Asian countries. In Japan, the first case was confirmed in a daily farm in Fukuoka Prefecture in November 2024. Although no new cases have been reported since January of this year (as of June 20), ongoing outbreaks in neighboring countries indicate that the risk of reintroduction remains high.

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Measles virus is the pathogen that causes measles and is highly infectious. Measles virus uses two molecules as viral receptors: signaling lymphocytic activation molecule, expressed on immune cells, and nectin-4, expressed on epithelial cells. Usage of these receptors is strongly associated with the pathogenesis of measles. Although it remains a leading cause of childhood mortality worldwide, measles elimination is being promoted by the availability of a highly effective live attenuated vaccines. Due to the elimination of measles in many countries, the circulating measles genotypes have been reduced to two, B3 and D8, in recent years. Therefore, in addition to genotyping using the conventional 450-nucleotide N gene region, new methods such as wholegenome sequencing and analysis of the M-F non-coding region are being tested for case association and outbreak tracking. Although measles virus is a single serotype, there are genomic differences among genotypes, including variations in B-cell and T-cell epitopes. However, current live attenuated vaccines remain sufficiently effective against all genotypes. On the other hand, the maintenance of protective immunity in vaccinees may become increasingly important, since vaccine-induced immunity tends to wane over time unlike the more durable immunity following natural infection.

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As of May 2025, measles outbreaks have been occurring worldwide. Japan has reported the highest number of cases since the beginning of the COVID-19. Unvaccinated measles cases are highly contagious and at high risk for serious illness, so it is important to ensure that children receive the live attenuated measles-rubella (MR) vaccine as soon as they become one year old. Additionally, the second routine immunization coverage rate must be raised to 95% or higher among five-to six- year-old children (one year before entering elementary school). For elementary school students and older individuals, it is important to check the vaccine records showing two doses of a measles-containing vaccine administered at or after one year of age. Those born on or after April 2, 1990, had the opportunity to receive two routine vaccinations; however, their records must be checked to confirm receipt. We also recommend checking vaccination records before traveling abroad. Additionally, rapid active epidemiological surveillance should be conducted in the event of a single measles case. Emergency vaccination within 72 hours of exposure for susceptible individuals may prevent the disease. For individuals ineligible for vaccination, health insurance covers the prevention of severe disease through an intramuscular injection of human immunoglobulin within six days of exposure. The most important measure is prophylaxis prior to exposure to the measles virus.

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[in Japanese]

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HIV replication highly interacts with host immunity resulting in life-long persistent virus replication in the presence of adaptive immune responses. Development of an effective vaccine is a key for control of global HIV epidemic, but immunization methods to induce effective anti-HIV immune responses have not been established. We have been focusing on analyzing virus-host immune interaction in vivo using animal models and applying findings to the development of vaccines. We have developed a novel immunogen selectively inducing virus-specific CD8+ T-cell responses and showed protective efficacy of vaccines against intrarectal SIV challenge. We have also worked on antibody responses, and determined the polymorphism in germline immunoglobulin genes in macaques and its association with induction of a particular class of anti-SIV neutralizing antibody. We applied the knowledge in HIV research to HTLV and COVID-19, showing protective efficacy of vaccine-induced neutralizing antibody against HTLV infection and viral suppression by vaccine-induced CD8+ T-cell responses against SARS-CoV-2 in macaque models.

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Many of the emerging and re-emerging viral diseases that have caused global outbreaks in recent years —such as severe acute respiratory syndrome (SARS), dengue fever, Zika virus disease, and COVID-19 —are caused by positive-sense single-stranded RNA (+ssRNA) viruses. This review focuses on members of the Flaviviridae family, a diverse group of +ssRNA viruses that exhibit distinct host and tissue tropisms, and summarizes our recent efforts to elucidate the molecular determinants underlying their pathogenicity and tropism. By refining reverse genetics systems that enable precise manipulation of viral genomes, we have uncovered the functional roles of specific viral proteins in pathogenesis through experimental infections using animal models that recapitulate disease phenotypes. In addition, by analyzing structural variations within viral genomes, we successfully identified key elements responsible for determining viral specificity. We have also developed innovative viral reporter assays that incorporate advanced imaging technologies, enabling real-time visualization of viral dynamics in vivo and facilitating diagnostic applications. This review integrates these findings to provide insights into how pathogenicity and tissue tropism evolve through repeated interspecies transmission, and discusses the potential of such approaches as a foundational platform for future infectious disease research and countermeasures.

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Epstein-Barr virus (EBV), a member of the herpesvirus family, infects more than 90% of adults and establishes a lifelong latent infection. In addition to its involvement in a wide range of malignancies such as lymphomas, nasopharyngeal carcinoma, and gastric cancer, recent evidence has shown its potential association with autoimmune diseases, positioning EBV as an interdisciplinary research model linking virology, oncology, and immunology. Historically, EBV research has been hindered by technical limitations in viral culture systems and animal models. However, recent advances—including whole-genome cloning using bacterial artificial chromosomes (BACs), gene editing via CRISPR/Cas9, and the development of in vivo models such as humanized mice—have accelerated the elucidation of EBV’ s unique life cycle and tumorigenic mechanisms. In this review, we discuss the evolution of techniques for generating recombinant EBVs and in vivo modeling, both essential for functional genetic analysis, and highlight our contributions to the advancement of these tools and their application in researching EBV-associated tumorigenesis.

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