A Different Epidemiology of Enterovirus A and Enterovirus B Co-circulating in Korea, 2012-2019

Emergence and circulation of enterovirus B species in infants in southern China: A multicenter retrospective analysis

BACKGROUND

Enteroviruses (EV) are common and can cause severe diseases, particularly in young children. However, the information of EV infection in infants in China is limited due to the vast population size and extensive geographical area of the country. Here, we conducted a retrospective multicenter analysis of available EV data to assess the current epidemiological situation in the infant population in southern China.

METHODS

The study enrolled infants with suspected EV infection from 34 hospitals across 12 cities in southern China between 2019 to 2022, and the confirmation of EV was done using RT-PCR and VP1 gene sequencing.

RESULTS

Out of 1221 infants enrolled, 330 (27.03%) were confirmed as EV-infected. Of these, 260 (78.79%) were newborns aged 0-28 days. The EV belonged to three species: EV-B (80.61%), EV-A (11.82%), and human rhinovirus (7.58%). Newborns were more susceptible to EV-B than older infants (p < 0.001). Within EV-B, we identified 15 types, with coxsackievirus (CV) B3 (20.91%), echovirus (E) 11 (19.70%), and E18 (16.97%) being the most common. The predominant EV types changed across different years. EV infection in infants followed a seasonal pattern, with a higher incidence from May to August. Furthermore, perinatal mother-to-child EV transmission in 12 mother-newborn pairs were observed.

CONCLUSION

Our study is the first to demonstrate the emergence and widespread circulation of EV-B species, mainly CVB3, E11, and E18, in southern China, primarily affecting young infants. This research provides valuable insights for future epidemic assessment, prediction, as well as the elimination of mother-to-child transmission.

Enteroviruses: epidemic potential, challenges and opportunities with vaccines

Enteroviruses (EVs) are the most prevalent viruses in humans. EVs can cause a range of acute symptoms, from mild common colds to severe systemic infections such as meningitis, myocarditis, and flaccid paralysis. They can also lead to chronic diseases such as cardiomyopathy. Although more than 280 human EV serotypes exist, only four serotypes have licenced vaccines. No antiviral drugs are available to treat EV infections, and global surveillance of EVs has not been effectively coordinated. Therefore, poliovirus still circulates, and there have been alarming epidemics of non-polio enteroviruses. Thus, there is a pressing need for coordinated preparedness efforts against EVs.This review provides a perspective on recent enterovirus outbreaks and global poliovirus eradication efforts with continuous vaccine development initiatives. It also provides insights into the challenges and opportunities in EV vaccine development. Given that traditional whole-virus vaccine technologies are not suitable for many clinically relevant EVs and considering the ongoing risk of enterovirus outbreaks and the potential for new emerging pathogenic strains, the need for new effective and adaptable enterovirus vaccines is emphasized.This review also explores the difficulties in translating promising vaccine candidates for clinical use and summarizes information from published literature and clinical trial databases focusing on existing enterovirus vaccines, ongoing clinical trials, the obstacles faced in vaccine development as well as the emergence of new vaccine technologies. Overall, this review contributes to the understanding of enterovirus vaccines, their role in public health, and their significance as a tool for future preparedness.

Genetic diversity and recombination of bovine enterovirus strains in China

Bovine enterovirus (BEV) consisting of enterovirus species E (EV-E) and F (EV-F) is the causative agent associated with respiratory and gastrointestinal diseases in cattle. Here, we reported the characterization, genetic diversity, and recombination of novel BEV strains isolated from the major cattle-raising regions in China during 2012-2018. Twenty-seven BEV strains were successfully isolated and characterized. Molecular characterization demonstrated that the majority of these novel BEV strains (24/27) were EV-E, while only few strains (3/27) were EV-F. Sequence analysis revealed the diversity of the circulating BEV strains such as species and subtypes where different species or subtype coinfections were detected in the same regions and even in the same cattle herds. For the EV-E, two novel subtypes, designated as EV-E6 and EV-E7, were revealed in addition to the currently reported EV-E1-EV-E5. Comparative genomic analysis revealed the intraspecies and interspecies genetic exchanges among BEV isolates. The representative strain HeN-B62 was probably from AN12 (EV-F7) and PS-87-Belfast (EV-F3) strains. The interspecies recombination between EV-E and EV-F was also discovered, where the EV-F7-AN12 might be from EV-E5 and EV-F1, and EV-E5-MexKSU/5 may be recombined from EV-F7 and EV-E1. The aforementioned results revealed the genetic diversity and recombination of novel BEV strains and unveiled the different BEV species or subtype infections in the same cattle herd, which will broaden the understanding of enterovirus genetic diversity, recombination, pathogenesis, and prevention of disease outbreaks.

IMPORTANCE

Bovine enterovirus (BEV) infection is an emerging disease in China that is characterized by digestive, respiratory, and reproductive disorders. In this study, we first reported two novel EV-E subtypes detected in cattle herds in China, unveiled the coinfection of two enterovirus species (EV-E/EV-F) and different subtypes (EV-E2/EV-E7, EV-E1/EV-E7, and EV-E3/EV-E6) in the same cattle herds, and revealed the enterovirus genetic exchange in intraspecies and interspecies recombination. These results provide an important update of enterovirus prevalence and epidemiological aspects and contribute to a better understanding of enterovirus genetic diversity, evolution, and pathogenesis.

Investigating the virulence of coxsackievirus B6 strains and antiviral treatments in a neonatal murine model

Coxsackievirus B6 (CVB6), a member of the human enterovirus family, is associated with severe diseases such as myocarditis in children. However, to date, only a limited number of CVB6 strains have been identified, and their characterization in animal models has been lacking. To address this gap, in this study, a neonatal murine model of CVB6 infection was established to compare the replication and virulence of three infectious-clone-derived CVB6 strains in vivo. The results showed that following challenge with a lethal dose of CVB6 strains, the neonatal mice rapidly exhibited a series of clinical signs, such as weight loss, limb paralysis, and death. For the two high-virulence CVB6 strains, histological examination revealed myocyte necrosis in skeletal and cardiac muscle, and immunohistochemistry confirmed the expression of CVB6 viral protein in these tissues. Real-time PCR assay also revealed higher viral loads in the skeletal and cardiac muscle than in other tissues at different time points post infection. Furthermore, the protective effect of passive immunization with antisera and a neutralizing monoclonal antibody against CVB6 infection was evaluated in the neonatal mouse model. This study should provide insights into the pathogenesis of CVB6 and facilitate further research in the development of vaccines and antivirals against CVBs.

Cost-effective complete genome sequencing using the MinION platform for identification of recombinant enteroviruses

IMPORTANCE

By employing a cost-effective approach for complete genome sequencing, the study has enabled the identification of novel enterovirus strains and shed light on the genetic exchange events during outbreaks. The success rate of genome sequencing and the scalability of the protocol demonstrate its practical utility for routine enterovirus surveillance. Moreover, the study's findings of recombinant strains of EVA71 and CVA2 contributing to epidemics in Malaysia and Taiwan emphasize the need for accurate detection and characterization of enteroviruses. The investigation of the whole genome and upstream ORF sequences has provided insights into the evolution and spread of enterovirus subgenogroups. These findings have important implications for the prevention, control, and surveillance of enteroviruses, ultimately contributing to the understanding and management of enterovirus-related illnesses.

Optimization of RT-PCR methods for enterovirus detection in groundwater

Enteroviruses (EVs), which belong to the Picornaviridae family, infect individuals asymptomatically or cause mild symptoms (fever, runny nose, cough, skin rash, sneezing, mouth blister). Severe cases can cause various diseases, such as acute hemorrhagic conjunctivitis, aseptic meningitis, or myocarditis, especially in infants. These viruses can be transmitted via the fecal-oral route via contaminated water. In this study, we established a polymerase chain reaction (PCR) method for detecting EVs in water sample using Coxsackievirus B5 (CV-B5) and Echovirus 30 (E-30), which belong to species B of the four species of EVs (EV-A to D). Several methods have been investigated and compared for the detection of EVs, including real-time reverse transcription (RT) polymerase chain reaction and conventional RT-PCR. The most sensitive primer sets were selected, and the PCR conditions were modified to increase sensitivity. We also quantified the detection limits of real-time and conventional RT-PCR. The detection limits of conventional RT-PCR were detected in 105-106 copy/mL for CV-B5 and 106-107 copy/mL for E-30, respectively. This optimized method for detecting EVs is expected to contribute substantially to the investigation of EV outbreaks in water samples.

Enterovirus Meningitis without Pleocytosis: a Retrospective Observational Study in Adults

Reverse-transcription polymerase chain reaction (RT-PCR)-confirmed enterovirus (EV) meningitis without pleocytosis has only been previously reported in children. In this study, we examined the frequency of EV meningitis without pleocytosis in adults and compared its clinical features. We retrospectively analyzed the data of adult patients with EV meningitis confirmed using cerebrospinal fluid (CSF) RT-PCR. Among the 17 patients included in this study, 58.8% showed no pleocytosis. The median age and clinical symptoms did not differ between the pleocytosis and non-pleocytosis groups. There were no statistically significant differences in seasonal variation or time from the onset of meningitis symptoms to lumbar puncture. The peripheral white blood cell (WBC) count in patients with pleocytosis was significantly higher than that in patients without pleocytosis. The median CSF pressure showed a higher trend in the non-pleocytosis group. Patients with CSF pressures higher than normal were more common in the non-pleocytosis group. The median CSF protein values were higher than the normal values in both groups. We confirmed the high frequency of EV meningitis without pleocytosis in adults. Accurate diagnosis using RT-PCR is necessary when meningitis symptoms are prominent during an EV epidemic, and CSF protein levels and pressure are high, even if the CSF WBC count is normal.

Non-Polio Enterovirus Surveillance in the Ural Federal District and Western Siberia, 2022: Is There a Need for a Vaccine?

Human non-polio enteroviruses (NPEVs) are the etiological agents involved in most cases of hand-foot-and-mouth disease (HFMD), herpangina and aseptic meningitis. Information on the epidemiology profiles of NPEV in the Ural Federal District and Western Siberia is very limited, with no published data available. The aim of this study is to describe NPEV incidence in the Ural Federal District and Western Siberia among patients with different forms of non-polio enterovirus infections (NPEVIs) during 2022, stratified by age and clinical manifestations. A total of 265 samples that tested positive for NPEV using a polymerase chain reaction (PCR) were genotyped by semi-nested PCR for the VP1 gene. The results showed that 21 genotypes were identified among patients in this study. CVA6 was the most common genotype for HFMD. CVA6, along with CVA10, accounted for the majority of herpangina cases, while CVA9 was implicated in most meningitis cases. Sequence and phylogenetic analysis showed that nearly all of the CVA6 strains identified in this study displayed a close genetic relationship to strains identified in other cities in Russia and strains from China. NPEV surveillance allows for monitoring the circulation of clinically relevant genotypes, resulting in continuous data about NPEV epidemiology. This is important for improving case prevention, diagnosis and guiding clinical management.

Non-polio enterovirus aseptic meningitis in infants up to three months of age, the bacterial mask of viral disease: A retrospective cohort study

BACKGROUND

Non-polio enterovirus aseptic meningitis (NPE-AM) is a self-limiting illness that can mimic serious bacterial infection (SBI) in infants during their first months of life.

OBJECTIVES

To compare the clinical features of febrile infants diagnosed with NPE-AM with those of infants who had SBI or non-bacterial infection (NBI).

STUDY DESIGN

A systematic series of febrile infants < 3-months-old hospitalized between 2010 and 2019 with febrile illness in a tertiary hospital. Clinical and laboratory data were compared between the three groups.

RESULTS

Overall 1278 infants were included; 207 (16.2%) had NPE-AM, 210 (16.4%) SBI and 861 (67.4%) NBI. The median age was 34 (IQR: 21.5-51.7) days. NPE-AM was documented in 25% of infants < 29 days and 9.9% of infants aged 29-90 days. Infants with NPE-AM or SBI had fever >39°C more frequently, 24.2% and 17.1% compared with 10% in infants with NBI (p < 0.001). Fever duration ≥ 2 days was reported in 3.4% of infants with NPE-AM vs 18.6% in SBI and 26.3% in NBI (p < 0001); rash occurred in 37.7% in NPE-AM compared to 4.6% in NBI and 5.7% in SBI (p < 0.001). The mean white blood count, C-reactive protein and absolute neutrophil count were significantly lower in infants with NPE-AM compared to infants with the SBI (p < 0.001) and similar to the means in infants with NBI (p = 0.848, 0.098 and 0.764 respectively). A high proportion of bloody tap 346/784 (53.1%) was detected. Infants with NPE-AM were more likely to be treated with antibiotics than infants with NBIs (88.9% vs 50.7%, p < 0.001), similarly to infants with SBIs (p = 0.571).

CONCLUSIONS

The clinical presentation of infants with NPE-AM that could mimic bacterial infection and the high rate of bloody taps may lead to more hospital admissions and antibiotic prescriptions. Rapid molecular testing for detection of NPE may be of additional value in the evaluation of febrile infants.

Increased detection of Echovirus 6-associated meningitis in patients hospitalized during the COVID-19 pandemic, Israel 2021-2022

BACKGROUND

Outbreaks of enteroviral meningitis occur periodically and may lead to hospitalization and severe disease.

OBJECTIVE

To analyze and describe the meningitis outbreak in patients hospitalized in Israel in 2021-2022, during the COVID-19 pandemic.

RESULTS

In December 2021, before the emergence of the SARS-CoV-2 omicron variant, an off-season increase in enterovirus (EV) infections was observed among patients hospitalized with meningitis. In January 2022, enterovirus cases decreased by 66% in parallel with the peak of the Omicron wave, and then increased rapidly by 78% in March (compared with February) after a decline in Omicron cases. Sequencing of the enterovirus-positive samples showed a dominance of echovirus 6 (E-6) (29%) before and after the Omicron wave. Phylogenetic analysis found that all 29 samples were very similar and all clustered in the E-6 C1 subtype. The main E-6 symptoms observed were fever and headache, along with vomiting and neck stiffness. The median patient age was 25 years, with a broad range (0-60 years).

CONCLUSION

An upsurge in enterovirus cases was observed after the decline of the SARS-CoV-2 omicron wave. The dominant subtype was E-6, which was present prior to the emergence of the omicron variant, but increased rapidly only after the omicron wave decline. We hypothesize that the omicron wave delayed the rise in E-6-associated meningitis.

Analysis of the epidemiological trends of enterovirus A in Asia and Europe

BACKGROUND

Enteroviruses have been in massive, cyclical epidemics worldwide. An in-depth understanding of the international epidemiological characteristics of Enterovirus A (EVA) is critical to determining its clinical significance and total disease burden. Although much research has been conducted on EVA epidemiology, there is still a lack of a comprehensive overview of EVA epidemiological characteristics and trends.

OBJECTIVE

EVA nucleic acid sequences from the NCBI virus database were used to summarize the epidemic time (based on the time of specimen collection), spatial and serotype distribution of EVA, and to analyze EVA isolated from cerebrospinal fluid specimens.

METHODS

EVA sequences were searched in NCBI Virus by keyword ("Enterovirus A″ or "EVA") to screen sequences released before December 2021 and sort them to analyze EVA by year, geographic region and serotype prevalence.

RESULTS

The results found 23,041 retrieved nucleic acid sequences with precise collection dates and geographical regions as of December 2021, with Asia accounting for 87%, Europe for 11% and Africa and the Americas for only 2%. Overall, EV-A71, CVA6 and CVA16 are a few of the main prevalent serotypes; and the prevalence characteristics of the different serotypes change over time from place to place.

CONCLUSION

The prevalence of different serotypes of EVA varies considerably over time and space, and we focused on analysing the epidemiological characteristics of EVAs in Asia and Europe and EVAs that invade the nervous system. This study will likely provide important clues for prevention, control and future research in virological surveillance, disease management and vaccine development.

Revisiting fecal metatranscriptomics analyses of macaques with idiopathic chronic diarrhoea with a focus on trichomonad parasites

Trichomonads, anaerobic microbial eukaryotes members of the phylum Parabasalia, are common obligate extracellular symbionts that can lead to pathological or asymptomatic colonization of various mucosal surfaces in a wide range of animal hosts. Results from previous in vitro studies have suggested a number of intriguing mucosal colonization strategies by Trichomonads, notably highlighting the importance of interactions with bacteria. However, in vivo validation is currently lacking. A previous metatranscriptomics study into the cause of idiopathic chronic diarrhoea in macaques reported the presence of an unidentified protozoan parasite related to Trichomonas vaginalis. In this work, we performed a reanalysis of the published data in order to identify the parasite species present in the macaque gut. We also leveraged the information-rich metatranscriptomics data to investigate the parasite behaviour in vivo. Our results indicated the presence of at least 3 genera of Trichomonad parasite; Tetratrichomonas, Pentatrichomonas and Trichomitus, 2 of which had not been previously reported in the macaque gut. In addition, we identified common in vivo expression profiles shared amongst the Trichomonads. In agreement with previous findings for other Trichomonads, our results highlighted a relationship between Trichomonads and mucosal bacterial diversity which could be influential in health and disease.

Long-term sentinel surveillance of enteroviruses in Gwangju, South Korea, 2011-2020

Human enteroviruses (EVs) are associated with a broad spectrum of diseases. To understand EV epidemiology, we present longitudinal data reflecting changing EV prevalence patterns in South Korea. We collected 7160 specimens from patients with suspected EV infections in ten hospitals in Gwangju, Korea during 2011-2020. RNA extraction and real-time reverse transcription polymerase chain reaction using EV-specific probes and primers were performed. EV genotyping and phylogenetic analysis were performed; EVs were detected in 3076 samples (43.0%), and the annual EV detection rate varied. EV infection rates did not differ with sex, and children aged ≤ 4 years were the most prone to EV infection; this trend did not change over time. Overall, 35 different EV types belonging to four distinctive species and rhinoviruses were identified. Although serotype distribution changed annually, the most frequently observed EVs were EV-A71 (13.1% of the cases), CVA6 (8.3%), CVB5 (7.6%), CVA16 (7.6%), CVA10 (7.5%), E18 (7.5%), E30 (7.0%), and E11 (5.0%) during 2011-2020. The predominant EV genotypes by clinical manifestation were CVB5 for aseptic meningitis; EV-A71 for hand, foot, and mouth disease cases; and CVA10 for herpangina. These results will aid the development of vaccines against EV infection and allow comprehensive disease control.

Pseudotyped Viruses for Enterovirus

Using a non-pathogenic pseudotyped virus as a surrogate for a wide-type virus in scientific research complies with the recent requirements for biosafety. Enterovirus (EV) contains many species of viruses, which are a type of nonenveloped virus. The preparation of its corresponding pseudotyped virus often needs customized construction compared to some enveloped viruses. This article describes the procedures and challenges in the construction of pseudotyped virus for enterovirus (pseudotyped enterovirus, EVpv) and also introduces the application of EVpv in basic virological research, serological monitoring, and the detection of neutralizing antibody (NtAb).

Hand-Foot-and-Mouth Disease-Associated Enterovirus and the Development of Multivalent HFMD Vaccines

Hand-foot-and-mouth disease (HFMD) is an infectious disease of children caused by more than 20 types of enteroviruses, with most cases recovering spontaneously within approximately one week. Severe HFMD in individual children develops rapidly, leading to death, and is associated with other complications such as viral myocarditis and type I diabetes mellitus. The approval and marketing of three inactivated EV-A71 vaccines in China in 2016 have provided a powerful tool to curb the HFMD epidemic but are limited in cross-protecting against other HFMD-associated enteroviruses. This review focuses on the epidemiological analysis of HFMD-associated enteroviruses since the inactivated EV-A71 vaccine has been marketed, collates the progress in the development of multivalent enteroviruses vaccines in different technical routes reported in recent studies, and discusses issues that need to be investigated for safe and effective HFMD multivalent vaccines.

Genetic and Cross Neutralization Analyses of Coxsackievirus A16 Circulating in Taiwan from 1998 to 2021 Suggest Dominant Genotype B1 can Serve as Vaccine Candidate

Coxsackievirus A16 (CVA16) is well known for causing hand-foot-and-mouth disease (HFMD) and outbreaks were frequently reported in Taiwan in the past twenty years. The epidemiology and genetic variations of CVA16 in Taiwan from 1998 to 2021 were analyzed in this study. CVA16 infections usually occurred in early summer and early winter, and showed increased incidence in 1998, 2000-2003, 2005, 2007-2008, and 2010 in Taiwan. Little or no CVA16 was detected from 2017 to 2021. CVA16 infection was prevalent in patients between 1 to 3 years old. A total of 69 isolates were sequenced. Phylogenetic analysis based on the VP1 region showed that CVA16 subgenotype B1 was dominantly isolated in Taiwan from 1998 to 2019, and B2 was identified only from isolates collected in 1999 and 2000. There was a high frequency of synonymous mutations in the amino acid sequences of the VP1 region among CVA16 isolates, with the exception of position 145 which showed positive selection. The recombination analysis of the whole genome of CVA16 isolates indicated that the 5'-untranslated region and the non-structural protein region of CVA16 subgenotype B1 were recombined with Coxsackievirus A4 (CVA4) and enterovirus A71 (EVA71) genotype A, respectively. The recombination pattern of subgenotype B2 was similar to B1, however, the 3D region was similar to EVA71 genotype B. Cross-neutralization among CVA16 showed that mouse antisera from various subgenotypes viruses can cross-neutralize different genotype with high neutralizing antibody titers. These results suggest that the dominant CVA16 genotype B1 can serve as a vaccine candidate for CVA16.

Co-infection and enterovirus B: post EV-A71 mass vaccination scenario in China

BACKGROUND

Hand, foot, and mouth disease (HFMD) is a common child infectious disease caused by more than 20 enterovirus (EV) serotypes. In recent years, enterovirus A71 (EV-A71) has been replaced by Coxsackievirus A6 (CV-A6) to become the predominant serotype. Multiple EV serotypes co-circulate in HFMD epidemics, and this study aimed to investigate the etiological epidemic characteristics of an HFMD outbreak in Kunming, China in 2019.

METHODS

The clinical samples of 459 EV-associated HFMD patients in 2019 were used to amplify the VP1 gene region by the three sets of primers and identify serotypes using the molecular biology method. Phylogenetic analyses were performed based on the VP1 gene.

RESULTS

Three hundred and forty-eight cases out of 459 HFMD patients were confirmed as EV infection. Of these 191 (41.61%) were single EV infections and 34.20% had co-infections. The EVs were assigned to 18 EV serotypes, of which CV-A6 was predominant (11.33%), followed by CV-B1 (8.93%), CV-A4 (5.23%), CV-A9 (4.58%), CV-A 16 (3.49%) and CV-A10 and CVA5 both 1.96%. Co-infection of CV-A6 with other EVs was present in 15.25% of these cases, followed by co-infection with CV-A16 and other EVs. The VP1 sequences used in the phylogenetic analyses showed that the CV-A6, CV-B1 and CV-A4 sequences belonged to the sub-genogroup D3 and genogroups F and E, respectively.

CONCLUSION

Co-circulation and co-infection of multiple serotypes were the etiological characteristic of the HFMD epidemic in Kunming China in 2019 with CV-A-6, CV-B1 and CV-A4 as the predominant serotypes. This is the first report of CV-B1 as a predominant serotype in China and may provide valuable information for the diagnosis, prevention and control of HFMD.

Human FcRn Is a Two-in-One Attachment-Uncoating Receptor for Echovirus 18

Virus-receptor interactions determine viral host range and tissue tropism. CD55 and human neonatal Fc receptor (FcRn) were found to be the binding and uncoating receptors for some of the echovirus-related enterovirus species B serotypes in our previous study. Echovirus 18 (E18), as a member of enterovirus species B, is a significant causative agent of aseptic meningitis and viral encephalitis in children. However, it does not use CD55 as a critical host factor. We conducted CRISPR/Cas9 knockout screening to determine the receptors and entry mechanisms and identified FcRn working as a dual-function receptor for E18. Knockout of FCGRT and B2M, which encode the two subunits of FcRn, prevented infection by E18 and other echoviruses in the same physiological cluster. We then elucidated the underlying molecular mechanism of receptor recognition by E18 using cryogenic electron microscopy. The binding of the FCGRT subunit to the canyon region rotates the residues around the pocket, triggering the release of the pocket factor as observed for other enterovirus species B members.

Epidemiology and clinical manifestations of different enterovirus and rhinovirus types show EV‐D68 may still impact on severity of respiratory infections

Respiratory infections are often caused by enteroviruses (EVs). The aim of this study was to identify whether certain types of EV were more likely to cause severe illness in 2016, when an increasing spread of upper respiratory infections was observed in Gothenburg, Sweden. The EV strain in 137 of 1341 nasopharyngeal samples reactive for EV by polymerase chain reaction could be typed by sequencing the viral 5′‐untranslated region and VP1 regions. Phylogenetic trees were constructed. Patient records were reviewed. Hospital care was needed for 46 of 74 patients with available medical records. The majority of the patients (83) were infected with the rhinovirus (RV). The remaining 54 were infected with EV A, B, C, and D strains of 13 different types, with EV‐D68 and CV‐A10 being the most common (17 vs. 14). Significantly more patients with EV‐D68 presented with dyspnea, both when compared with other EV types (p = 0.003) and compared to all other EV and RV infections (p = 0.04). Phylogenetic analysis of the sequences revealed the spread of both Asian and European CV‐A10 strains and 12 different RV C types. This study showed an abundance of different EV types spreading during a year with increased upper respiratory increased infections. EV‐D68 infections were associated with more severe disease manifestation. Other EV and RV types were more evenly distributed between hospitalized and nonhospitalized patients. The EV type CV‐A10 was also found in infected patients, which warrants further studies and surveillance, as this pathogen could cause more severe disease and outbreaks of hand, foot, and mouth disease.

Proliferation characteristics of coxsackievirus A10 in mice and immune protection ability of experimental inactivated vaccine

Coxsackievirus A10 (CVA10) is the main pathogen of hand, foot, and mouth disease in China. However, there are no CVA10-specific drugs and vaccines, and the pathogenesis and effects of this virus in the body are unknown. We investigated the effect of a clinically isolated CVA10 virus strain (CVA10-25) to investigate its effect in suckling mice through different infection routes. We observed the dynamic distribution and proliferation of the virus in mouse tissues by infecting suckling mice with different doses of the virus and mice of different ages with the same dose of the virus. We also analysed the pathological characteristics after infection. A formaldehyde-inactivated experimental vaccine was prepared to immunise 5-week-old BALB/c female mice three times, and newborn suckling mice were tested for the presence of maternally transmitted antibodies. The viral load in each organ after intracerebral administration was higher than that after intraperitoneal administration; the peroral administration route did not cause disease in mice. Mouse paralysis and death after infection were related to age. The skeletal muscles, heart, and lung showed histopathological changes after infection. We established a 2-day-old BALB/c suckling mouse model that could be infected intracranially to study the pathogenesis and pathology of CVA10. Maternally transmitted antibodies protected the mice against the virus. This study provides a reference for CVA10-related pathogenesis and vaccine research.

Striking Decrease of Enteroviral Meningitis in Children During the COVID-19 Pandemic

We report the unprecedented complete absence of pediatric enteroviral meningitis in 2020 in the area of Bern, Switzerland. Presumably an unintended effect of coronavirus disease 2019 public health measures, this finding highlights the potential of community-wide nonpharmaceutical interventions for controlling the circulation of a major pediatric pathogen, which is mainly transmitted by the fecal-oral route.

Non-Polio Enteroviruses from Acute Flaccid Paralysis Surveillance in Korea, 2012-2019

The risk of polio importation and re-emergence persists since epidemic polio still occurs in some countries, and the resurgence of polio occurring almost 20 years after polio eradication was declared in Asia has been reported. We analyzed the results of acute flaccid paralysis (AFP) surveillance in Korea to assess the quality of AFP surveillance and understand the etiology of non-polio enterovirus (NPEV)-associated central nervous system diseases in a polio-free area. We investigated 637 AFP patients under 15 years of age whose cases were confirmed during 2012–2019 by virus isolation, real-time reverse transcription polymerase chain reaction, and VP1 gene sequencing. Among the 637 AFP cases, NPEV was detected in 213 (33.4%) patients, with the majority observed in EV-A71, with 54.9% of NPEV positives. EV-A71 has been shown to play a role as a major causative agent in most neurological diseases except for Guillain-Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM), and meningitis. This study provides information on the AFP surveillance situation in Korea and highlights the polio eradication stage in the monitoring and characterization of NPEV against the outbreak of neurological infectious diseases such as polio.