The Way We Walked with Immunology.

It has been a little more than 50 years since we discovered IgE, a key molecule for the allergic response and a target for treating allergies and severe asthma. Here, I trace my career, from the kindling of my interest in immunochemistry to groundbreaking discoveries in the biology and chemistry of immunoglobulins. I describe my service to the broader community of immunologists and my role in shaping departments and research institutes. My course starts in Japan and includes Southern California, Baltimore, and Denver.

The construction of cross-population polygenic risk scores using transfer learning.

As most existing genome-wide association studies (GWASs) were conducted in European-ancestry cohorts, and as the existing polygenic risk score (PRS) models have limited transferability across ancestry groups, PRS research on non-European-ancestry groups needs to make efficient use of available data until we attain large sample sizes across all ancestry groups. Here we propose a PRS method using transfer learning techniques. Our approach, TL-PRS, uses gradient descent to fine-tune the baseline PRS model from an ancestry group with large sample GWASs to the dataset of target ancestry. In our application of constructing PRS for seven quantitative and two dichotomous traits for 10,285 individuals of South Asian ancestry and 8,168 individuals of African ancestry in UK Biobank, TL-PRS using PRS-CS as a baseline method obtained 25% average relative improvement for South Asian samples and 29% for African samples compared to the standard PRS-CS method in terms of predicted R2. Our approach increases the transferability of PRSs across ancestries and thereby helps reduce existing inequities in genetics research.

Macacine alphaherpesvirus 1 (B Virus) Infection in Humans, Japan, 2019.

Two human patients with Macacine alphaherpesvirus 1 infection were identified in Japan in 2019. Both patients had worked at the same company, which had a macaque facility. The rhesus-genotype B virus genome was detected in cerebrospinal fluid samples from both patients.

Clostridium butyricum Bacteremia Associated with Probiotic Use, Japan.

Clostridium butyricum, a probiotic commonly prescribed in Asia, most notably as MIYA-BM (Miyarisan Pharmaceutical Co., Ltd.; https://www.miyarisan.com), occasionally leads to bacteremia. The prevalence and characteristics of C. butyricum bacteremia and its bacteriologic and genetic underpinnings remain unknown. We retrospectively investigated patients admitted to Osaka University Hospital during September 2011-February 2023. Whole-genome sequencing revealed 5 (0.08%) cases of C. butyricum bacteremia among 6,576 case-patients who had blood cultures positive for any bacteria. Four patients consumed MIYA-BM, and 1 patient consumed a different C. butyricum-containing probiotic. Most patients had compromised immune systems, and common symptoms included fever and abdominal distress. One patient died of nonocclusive mesenteric ischemia. Sequencing results confirmed that all identified C. butyricum bacteremia strains were probiotic derivatives. Our findings underscore the risk for bacteremia resulting from probiotic use, especially in hospitalized patients, necessitating judicious prescription practices.

Sphingobium yanoikuyae Bacteremia, Japan.

We report a case of Sphingobium yanoikuyae bacteremia in an 89-year-old patient in Japan. No standard antimicrobial regimen has been established for S. yanoikuyae infections. However, ceftriaxone and ceftazidime treatments were effective in this case. Increased antimicrobial susceptibility data are needed to establish appropriate treatments for S. yanoikuyae.

Analysis of Suspected Measles Cases with Discrepant Measles-Specific IgM and rRT-PCR Test Results, Japan.

We investigated clinically suspected measles cases that had discrepant real-time reverse transcription PCR (rRT-PCR) and measles-specific IgM test results to determine diagnoses. We performed rRT-PCR and measles-specific IgM testing on samples from 541 suspected measles cases. Of the 24 IgM-positive and rRT-PCR--negative cases, 20 were among children who received a measles-containing vaccine within the previous 6 months; most had low IgG relative avidity indexes (RAIs). The other 4 cases were among adults who had an unknown previous measles history, unknown vaccination status, and high RAIs. We detected viral nucleic acid for viruses other than measles in 15 (62.5%) of the 24 cases with discrepant rRT-PCR and IgM test results. Measles vaccination, measles history, and contact history should be considered in suspected measles cases with discrepant rRT-PCR and IgM test results. If in doubt, measles IgG avidity and PCR testing for other febrile exanthematous viruses can help confirm or refute the diagnosis.

Helicobacter fennelliae Localization to Diffuse Areas of Human Intestine, Japan.

The site of enterohepatic Helicobacter colonization/infection in humans is still unknown. We report microbiologically and histopathologically confirmed H. fennelliae localization in the large intestine in an immunocompromised patient in Japan. This case contributes to better understanding of the life cycle of enterohepatic Helicobacter species.

Hepatitis B Virus Reactivation after Switch to Cabotegravir/Rilpivirine in Patient with Low Hepatitis B Surface Antibody.

A patient in Japan with HIV began antiretroviral therapy because of acute hepatitis B virus (HBV) 15 years ago, with low hepatitis B surface antibody, and experienced breakthrough HBV reactivation 4 months after switching from bictegravir/emtricitabine/tenofovir alafenamide to cabotegravir/rilpivirine. An immune escape mutation, E164V, was identified in the isolated HBV DNA.

Cocirculation of Genetically Distinct Highly Pathogenic Avian Influenza H5N5 and H5N1 Viruses in Crows, Hokkaido, Japan.

We isolated highly pathogenic avian influenza (HPAI) H5N5 and H5N1 viruses from crows in Hokkaido, Japan, during winter 2023-24. They shared genetic similarity with HPAI H5N5 viruses from northern Europe but differed from those in Asia. Continuous monitoring and rapid information sharing between countries are needed to prevent HPAI virus transmission.

Sporadic Occurrence of Ensitrelvir-Resistant SARS-CoV-2, Japan.

Using the GISAID EpiCoV database, we identified 256 COVID-19 patients in Japan during March 31-December 31, 2023, who had mutations in the SARS-CoV-2 nonstructural protein 5 conferring ensitrelvir resistance. Ongoing genomic surveillance is required to monitor emergence of SARS-CoV-2 mutations that are resistant to anticoronaviral drugs.

Infection- and Vaccine-Induced SARS-CoV-2 Seroprevalence, Japan, 2023.

We assessed SARS-CoV-2 seroprevalence in Japan during July-August 2023, with a focus on 2 key age groups, 0-15 and >80 years. We estimated overall seroprevalence of 45.3% for nucleocapsid antibodies and 95.4% for spike antibodies and found notable maternally derived spike antibodies in infants 6-11 months of age (90.0%).

Prevalence of and Risk Factors for Post-COVID-19 Condition during Omicron BA.5-Dominant Wave, Japan.

The increased risk for post-COVID-19 condition after the Omicron-dominant wave remains unclear. This population-based study included 25,911 persons in Japan 20-69 years of age with confirmed SARS-CoV-2 infection enrolled in the established registry system during July-August 2022 and 25,911 age- and sex-matched noninfected controls who used a self-reported questionnaire in January-February 2023. We compared prevalence and age- and sex-adjusted odds ratios of persistent COVID-19 symptoms (lasting ≥2 months). We evaluated factors associated with post-COVID-19 condition by comparing cases with and without post-COVID-19 condition. We analyzed 14,710 (8,392 cases and 6,318 controls) of 18,183 respondents. Post-COVID-19 condition proportion among cases was 11.8%, higher by 6.3% than 5.5% persistent symptoms among controls. Female sex, underlying medical conditions, mild to moderate acute COVID-19, and vaccination were associated with post-COVID-19 condition. Approximately 12% had post-COVID-19 condition during the Omicron-dominant wave, indicating the need for longer follow-up.

Fatal SARS-CoV-2 Infection among Children, Japan, January-September 20221.

To determine the characteristics of pediatric patients 0-19 years of age who died after onset of SARS-CoV-2 infection in Japan during January 1-September 30, 2022, we reviewed multiple sources. We identified 62 cases, collected detailed information from medical records and death certificates, and conducted interviews, resulting in 53 patients with detailed information for our study. Among 46 patients with internal causes of death (i.e., not external causes such as trauma), 15% were <1 year of age, 59% had no underlying disease, and 88% eligible for vaccination were unvaccinated. Nonrespiratory symptoms were more common than respiratory symptoms. Out-of-hospital cardiac arrest affected 46% of patients, and time from symptom onset to death was <7 days for 77%. Main suspected causes of death were central nervous system abnormalities (35%) and cardiac abnormalities (20%). We recommend careful follow-up of pediatric patients after SARS-CoV-2 infection during the first week after symptom onset, regardless of underlying diseases.

Vaccine Effectiveness against SARS-CoV-2 among Household Contacts during Omicron BA.2-Dominant Period, Japan.

We calculated attack rates for household contacts of COVID-19 patients during the SARS-CoV-2 Omicron BA.2-dominant period in Japan. Attack rates among household contacts without recent (<3 months) vaccination was lower for contacts of index patients with complete vaccination than for contacts of index patients without complete vaccination, demonstrating indirect vaccine effectiveness.

Analysis of the incidence and mortality trends of esophageal cancer in cancer registry areas of China and Japan.

This study aims to analyze the prevalence trend of esophageal cancer in Japan and China to provide suggestions for the prevention and treatment of esophageal cancer. The results showed that the incidence rate for the years 2010-2018 significantly decreased with an APC of 5.66%, and the mortality rate from 2010 to 2015 had an APC of -5.87% in China. However, the incidence rate of Japanese women showed an upward trend, with an APC of 4.09% from 2010 to 2019. The mortality rate of esophageal cancer in Japan showed a downward trend, with an APC of -2.96% from 2010 to 2021. From 2010 to 2018, Chinese esophageal squamous cell carcinoma accounted for the highest proportion, accounting for 85.96%, with the largest distribution in the middle, accounting for 47.25%. Patients are mostly diagnosed at stage III, and the relative survival rate from 2012 to 2015 was 30.3%. Japan also has the highest proportion of squamous cell carcinoma, and the lesions are also mostly located in the middle segment. While Japanese esophageal cancer patients are mostly diagnosed at stage I, and the relative survival rate was 41.5% in Japan from 2009 to 2011. The results of this article indicate that the current prevalence of esophageal cancer in China and Japan is generally declining, and the quality of life of patients is gradually improving, but effective screening and prevention strategies are still needed to reduce the burden of this disease.

Even though active recommendation for HPV vaccination has restarted, Japan's rates have not recovered.

Japan has a particularly critical situation surrounding its collapsed HPV vaccination program for preventing HPV-caused cervical cancers, a problem exacerbated by the lack of a national immunization database. We have determined the year-to-year HPV vaccination uptake by Japanese females and analyzed by birth fiscal year (FY) the monthly number of people receiving initial HPV vaccination. Our analysis covers the period from the start of public subsidies in 2010 to September 2023, using data provided by local governments. We calculated the cumulative number of monthly immunizations for those unimmunized as of April (the beginning of each vaccination year). The monthly number of initial HPV vaccinations was highest in August for every FY from FY 2010 to FY 2023; a second vaccination peak tended to occur in March when the vaccination year ended. The highest number of August vaccinations occurred in FY 2011, followed (in order) by 2012, 2021, 2022, 2023, and 2013. In Japan's ongoing catch-up vaccination program for young women, the monthly number of vaccinations increased in August 2022 but then slowed the following year. After FY 2021, the cumulative vaccination coverage of subjects unvaccinated at the beginning of the vaccination year but subsequently covered by routine immunizations was slightly improved. FY 2021 was when the governmental recommendations for HPV vaccination were resumed. More recent vaccination rates are considerably lower than those in FY 2011-2012 when vaccinations were first fully endorsed. Paralyzing HPV vaccination hesitancy, which began in FY 2013, will linger in Japan in FY 2024.

Effectiveness of catch-up and routine program of the 9-valent vaccine on cervical cancer risk reduction in Japan.

In 2013, the national human papillomavirus (HPV) immunization program began. However, in June 2013, Japan's Ministry of Health, Labor and Welfare (MHLW) announced a "temporary" suspension of its recommendation for the human papillomavirus vaccine. Finally, in November 2021, the MHLW ended its suspension of the recommendation of the HPV vaccine. To address the 9-year gap in HPV vaccinations the suspension had caused, the MHLW conducted a program of catch-up vaccinations from April 2022 to March 2025. Finally, in April 2023, the 9-valent HPV vaccine was approved for both the routine and catch-up vaccination programs in Japan. In this study, we investigated the potential effects of the introduction of the 9-valent vaccine on the increased risk of cervical cancer in females born after fiscal year (FY) 2000. We estimated the lifetime relative risk of cervical cancer incidence and death using the improved routine and catch-up vaccination rates after the recent resumption of the governmental recommendation for women and girls to have the HPV vaccination. These relative risks were calculated using a lifetime risk of 1.000 for cervical cancer incidence and death for females born in FY 1993. We predicted that even if a 90% vaccination rate were to be achieved by FY 2024 with the 9-valent vaccine among women born between FY 2000 and FY 2005, the risk would remain higher than for the vaccination generation. Therefore, for women born between FY 2000 and FY 2005, it will be necessary to significantly improve the cervical cancer screening rate to compensate for this increased risk.

A significant outbreak of respiratory human adenovirus infections among children aged 3-6 years in Hokkaido, Japan, in 2023.

Human adenovirus (HAdV) infections present diverse clinical manifestations upon infecting individuals, with respiratory infections predominating in children. We surveyed pediatric hospitalizations due to respiratory HAdV infections across 18 hospitals in Hokkaido Prefecture, Japan, from July 2019 to March 2024, recording 473 admissions. While hospitalizations remained below five cases per week from July 2019 to September 2023, a notable surge occurred in late October 2023, with weekly admissions peaking at 15-20 cases from November to December. There were dramatic shifts in the age distribution of hospitalized patients: during 2019-2021, 1-year-old infants and children aged 3-6 years represented 51.4%-54.8% and 4.1%-13.3%, respectively; however, in 2023-2024, while 1-year-old infants represented 19.0%-20.1%, the proportion of children aged 3-6 years increased to 46.2%-50.0%. Understanding the emergence of significant outbreaks of respiratory HAdV infections and the substantial changes in the age distribution of hospitalized cases necessitates further investigation into the circulating types of HAdV in Hokkaido Prefecture and changes in children's neutralizing antibody titers against HAdV.

Remarkable increase in the detection and molecular characterization of adenovirus F41 in children with acute gastroenteritis in Japan, 2017-2023.

Human adenovirus (HAdV) is one of the causative viruses of acute gastroenteritis (AGE) in children worldwide. Species F is known to be enteric adenovirus (genotypes 40 and 41) detected in stool samples. In Japan, we conducted an epidemiological study and molecular characterization of HAdV before and after the COVID-19 pandemic from 2017 to 2023. Among 821 patients, HAdV was detected in 118 AGE cases (14.4%). During a period of 6 years, the HAdV detection rates for each year were relatively low at 3.7% and 0%, in 2017-2018, and 2020-2021, respectively. However, the detection rate increased to remarkably high rates, ranging from 13.3% to 27.3% in the other 4-year periods. Of these HAdV-positive strains, 83.1% were F41 genotypes and 16.9% were other genotypes (A31, B3, C1, C2/C6, and C5). Phylogenetic analyses of the nucleotide and deduced amino acid sequences of the full-length hexon gene demonstrated that HAdV-F41 strains were comprised of three clades, and each clade was distributed across the study period from 2017 to 2023. Analysis of deduced amino acid sequences of the hexon gene of the representative HAdV-F41 strains from each clade revealed numerous amino acid substitutions across hypervariable regions (HVRs) from HVR-1 to HVR-7, two insertions in HVR-1 and HVR-7, and two deletions in HVR-1 and HVR-2 of the hexon gene compared to those of the prototype strain, particularly, those of clade 3 HAdV-F41 strains. The findings suggested that the HAdV-F41 of each clade was stable, conserved, and co-circulated for over two decades in Japan.

Survival Outcome Superiority of Total Pharyngolaryngectomy Compared with Chemoradiotherapy for T4aM0 Hypopharyngeal Squamous Cell Carcinoma: A Nationwide Database Study of Japan.

BACKGROUND: The purpose of this study is to elucidate whether total pharyngolaryngectomy (TPL) or chemoradiotherapy (CRT) provides a better prognostic outcome in patients with T4aM0 hypopharyngeal carcinoma (HPSCC) using a nationwide database. METHODS: All data were obtained from the Head and Neck Cancer Registry of Japan, and information from patients who were newly diagnosed with T4aM0 HPSCC between 2011 and 2015 was extracted. The primary endpoint was disease-specific survival (DSS), and the secondary endpoint was overall survival (OS). The inverse probability of treatment weighting (IPTW) adjustments was used for survival analyses. RESULTS: Our cohort included 1143 patients. The TPL and CRT groups included 724 and 419 patients, respectively. Following IPTW adjustments, both the OS and DSS of the TPL group were significantly longer than those of the CRT group (P = .02 and P = .002, respectively). CONCLUSIONS: Survival superiority was demonstrated for patients with T4aM0 HPSCC treated with TPL compared with those treated with CRT.