Nozomu Hanaoka

Human adenovirus type 3 (HAdV-3) in the species Mastadenovirus blackbeardi is a frequent cause of hundreds of respiratory infections in Japan, with outbreaks varying in clinical severity. Such a high frequency of cases could be due to regular migration of novel variants or persistent circulation of endemic strains. Either scenario would require different measures to ameliorate the burden on public health. We designed a new cost-effective whole-genome sequencing protocol based on tiled amplicons and nanopore sequencing to clarify the circumstances behind the frequent outbreaks. This protocol was used with clinical samples collected between 2011 and 2020 from Japanese patients with acute respiratory illness (n = 110), resulting in near whole-genome sequences (~99% length) for 105 samples with high read coverage (~262.6 ± 192 reads). Phylogenetic analysis indicated sustained circulation of endemic strains in Japan during the analyzed decade and their relation to other strains worldwide with publicly available genome sequences. However, a comparison with other Japanese HAdV-3 strains circulating since 2023 suggested the public health measures introduced during the COVID-19 pandemic (2020–2022) indirectly affected the prevalence of circulating HAdV-3 variants. Additionally, our approach enabled the detection and partial sequencing (~71% completion) of co-infecting strains from the species Mastadenovirus caesari (n = 4) in the examined samples. The detection of adenoviruses belonging to different species in the same sample highlights how our protocol enhances the distinction of circulating viruses. In conclusion, these results and the introduced protocol will enable timely characterization and clinical interventions to mitigate this virus.

Accurate diagnosis of adenoviral conjunctivitis is critical for timely treatment and infection control. However, conventional lateral flow kits often lack sufficient sensitivity, especially in mild cases. This multicenter prospective study evaluated the diagnostic performance of silver-amplified lateral flow kits (SA-LFKs) compared with non-silver-amplified kits (NSA-LFKs), using real-time polymerase chain reaction (qPCR) as the reference standard. Tear samples from 200 patients with suspected adenoviral conjunctivitis were collected across four clinics and analyzed for sensitivity, specificity, and genotype coverage. The SA-LFK demonstrated significantly higher sensitivity (86.0%) than the NSA-LFK (72.0%) (p < 0.001), with both kits showing high specificity (100% and 98.1%, respectively). Pooled analysis revealed that sensitivity was significantly lower in mild-to-moderate cases than in severe cases for both kits, suggesting that clinical severity influences detection performance. Across all severity levels, the SA-LFK consistently demonstrated higher sensitivity than the NSA-LFK, including in mild-to-moderate cases (77.8% vs. 59.3%, p = 0.004), supporting its superior diagnostic performance. The SA-LFK showed robust performance across eight identified adenovirus genotypes and maintained higher positivity rates even at lower viral loads. These findings support the clinical utility of SA-LFKs for early diagnosis and outbreak containment in diverse settings.

We investigated the IC ₅₀ values of BCV for novel HAdV types and found that the epidemic keratoconjunctivitis-associated HAdV-D54 prevalent in the Asian region was the most susceptible. In addition, the mean overall IC ₅₀ value of BCV was lower than that of CDV, indicating that BCV is effective against HAdVs.

Outbreaks of acute respiratory disease associated with human adenovirus (HAdV) B7d have been reported, including fatal cases in the United States. In 2018, we detected HAdV-B7d in a patient with urethritis, probably transmitted through sexual contact. Infectious HAdV-B7d was excreted in urine and gargle for >10 days after the disappearance of symptoms.

Seven species (A–G) of human mastadenovirus (HAdV) are known, and more than 100 types have been reported. HAdV is highly resistant to common hand sanitizers. Epidemic keratoconjunctivitis and pharyngoconjunctival fever caused by HAdV can be explosively transmitted in a confined space, resulting in outbreaks such as nosocomial infections. Given the absence of an antiviral agent for HAdV infection, it is important to prevent the spread of infection using disinfectants. The bactericidal and virucidal activities of ozone have already been known widely. ALTANT is an ozonated alcohol preparation developed by E-TECH Co., Ltd. (Kobe, Hyogo, Japan).In this study, ALTANT was mixed with different types of HAdV at a ratio of 9:1, and the viability of the HAdV was determined after instantaneous reactions for varying time periods (flash (< 3 seconds) to 5 minutes) using TCID50 assay. The assay results demonstrated that the viability of the HAdV decreased by 1/10 to 1/100 within 1 minute after the reaction, albeit slight differences in the reactivity observed among HAdV types. The viability of the HAdV decreased by a factor of >4log10, and the virus was completely killed in 3 minutes. This study demonstrated that ALTANT has a potent HAdV disinfection effect.

Between 2011 and 2018, 518 respiratory adenovirus infections were diagnosed in a pediatric clinic in Shizuoka, Japan. Detection and typing were performed by partial sequencing of both hexon- and fiber-coding regions which identified: adenovirus type 1 (Ad-1, n = 85), Ad-2 (n = 160), Ad-3 (n = 193), Ad-4 (n = 18), Ad-5 (n = 27), Ad-11 (n = 2), Ad-54 (n = 3), and Ad-56 (n = 1). Considering previous reports of the circulation of an endemic recombinant Ad-2, e.g., Ad-89, 100 samples typed as Ad-2 were randomly selected for further molecular typing by sequencing the penton base-coding region. Despite the high nucleotide sequence conservation in the penton base- coding region, 27 samples showed 98% identity to Ad-2. Furthermore, 14 samples showed 97.7% identity to Ad-2 and 99.8% identity to Ad-89, while the remaining 13 samples showed an average 98% pairwise identity to other Ad-C types and clustered with Ad-5. The samples typed as Ad-89 (n = 14) and as a recombinant Ad type (P5H2F2) (n = 13) represented 27% of cases originally diagnosed as Ad-2, and were detected sporadically. Therefore, two previously uncharacterized types in Japan, Ad-89 and a recombinant Ad-C, were shown to circulate in children. This study creates a precedent to evaluate the epidemiology and divergence among Ad-C types by comprehensively considering the type classification of adenoviruses.

Enteroviruses (EVs) are responsible for extremely large-scale, periodic epidemics in pediatric cohorts, particularly in East and Southeast Asia. Clinical presentation includes a diverse disease spectrum, including hand-foot and mouth disease (HFMD), aseptic meningitis, encephalitis, acute flaccid paralysis, and acute flaccid myelitis. HFMD is predominantly attributable to EV-A types, including the major pathogen EV-A71, and coxsackieviruses, particularly CV-A6, CV-A16, and CV-A10. There have been multiple EV-A71 outbreaks associated with a profound burden of neurological disease and fatal outcomes in Asia since the early 1980s. Efficacious vaccines against EV-A71 have been developed in China but widespread pediatric vaccination programs have not been introduced in other countries. Encephalitis, as a consequence of complications arising from HFMD infection, leads to damage to the thalamus and medulla oblongata. Studies in Vietnam suggest that myoclonus is a significant indicator of central nervous system (CNS) complications in EV-A71-associated HFMD cases. Rapid response in HFMD cases in children is imperative to prevent the progression to a CNS infection; however, prophylactic and therapeutic agents have not been well established internationally, therefore surveillance and functional studies including development of antivirals and multivalent vaccines is critically important to reduce disease burden in pediatric populations.

Background: Outbreaks of enterovirus D68 (EV‐D68) respiratory infections in children were reported globally in 2014. In Japan, there was an EV‐D68 outbreak in the autumn of 2015 (September–October). The aim of this study was to compare EV‐D68‐specific polymerase chain reaction (PCR)‐positive and EV‐D68‐specific PCR‐negative patients.Methods: Pediatric patients admitted for any respiratory symptoms between September and October 2015 were enrolled. Nasopharyngeal swabs were tested for multiplex respiratory virus PCR and EV‐D68‐specific reverse transcription‐PCR. EV‐D68‐specific PCR‐positive and ‐negative patients were compared regarding demographic data and clinical information.Results: A nasopharyngeal swab was obtained from 76 of 165 patients admitted with respiratory symptoms during the study period. EV‐D68 was detected in 40 samples (52.6%). Median age in the EV‐D68‐specific PCR‐positive and ‐negative groups was 3.0 years (IQR, 5.5 years) and 3.0 years (IQR, 4.0 years), respectively. The rates of coinfection in the two groups were 32.5% and 47.2%, respectively. There was no significant difference in the history of asthma or recurrent wheezing, length of hospitalization, or pediatric intensive care unit admission rate between the groups. The median days between symptom onset and admission was significantly lower for the EV‐D68‐positive group (3.0 days vs 5.0 days, P = 0.001). EV‐D68 was identified as clade B on phylogenetic analysis. No cases of acute flaccid myelitis were encountered.Conclusions: More than half of the samples from the children admitted with respiratory symptoms were positive for EV‐D68‐specific PCR during the outbreak. Asthma history was not associated with the risk of developing severe respiratory infection.

Objective: Approximately 1 million adenovirus immunochromatography (IC) kits are annually used in Japan. However, no practical strategies have been developed regarding their use for detecting adenovirus. The present study aims to verify the usefulness of clinical manifestations in making decisions regarding the use of adenovirus IC kits for children with upper respiratory infections (URI).Methods: The medical records of 825 pediatric cases tested by IC kits for adenovirus were extracted from clinical laboratory department database over a 3‐year period at our hospital. Among them, 585 patients were suspected adenovirus URI, and their clinical manifestations were reviewed. After data cleaning, 10 types of clinical manifestations were statistically analyzed between adenovirus IC kit‐positive and ‐negative groups. Multivariate analysis was performed to select significant clinical manifestations using adenovirus IC kit positivity as the objective variable.Results: Among 585 pediatric patients, the cases of 420 patients, with suitable data for whom no other pathogen was detected, were reviewed. Adenovirus was detected in 86 cases. Multivariate analysis identified a significant difference for three clinical manifestations: (1) fever ≥ 39.0°C, (2) rhinorrhea, and (3) tonsillar exudate. The negativity rate for the IC kit was 90% when none of the three manifestations was observed.Conclusions: The results suggested that IC kits for adenovirus tend to give negative results in cases that lack all the three above mentioned clinical manifestations.