Hand, Foot, and Mouth Disease Challenges and Its Antiviral Therapeutics

Childhood hand, foot and mouth disease sequelae cohort study in Henan, China: cohort profile

PURPOSE

The childhood hand, foot and mouth disease (HFMD) sequelae cohort study (HNHFMDCS) is an ambispective cohort study of patients with HFMD based in Henan Province, China, consisting of patients treated in a key hospital for the diagnosis and treatment of HFMD in Henan Province. The study aims to investigate the long-term sequelae of HFMD survivors and to provide a comprehensive understanding of the potential harm caused by this infectious disease.

PARTICIPANTS

In the retrospective phase of the cohort study, children diagnosed with HFMD from January 2014 to January 2023 were included, and clinical and demographic information about the patients was collected through a self-developed questionnaire. Patients hospitalised with HFMD since January 2023 were enrolled in the prospective cohort phase of the study, and long-term follow-up will be performed after completion of the baseline investigation (interview and comprehensive physical examination), clinical laboratory examination and biospecimen collection.

FINDINGS TO DATE

For the retrospective analysis of the cohort, a total of 18 705 HFMD cases (11 834 males and 6871 females) were observed between 2014 and 2022, of which 17 202 were mild cases (10 839 males and 6363 females) and 1503 were severe cases (995 males and 508 females). Statistical analysis was performed on the collected clinical examination data, and descriptive statistical methods, including mean value, SD and t-test, were used to compare the intergroup data. All tests were bilateral, and p<0.05 was considered statistically significant. There were significant differences in the hospitalisation duration and clinical examination indicators, such as platelets (PLT), C reactive protein (CRP), aspartate amino transferase (AST), alanine amino transferase (ALT), T lymphocyte subsets (CD3+ and CD3+CD4+) and B lymphocytes (CD19+) between mild and severe patients. The differences in these clinical examination indicators also help to detect changes in the disease in time so as to deeply understand the potential harm and social burden of the disease, and provide strong support for the rehabilitation of patients.

FUTURE PLANS

Prospective cohort studies are currently underway, primarily enrolling hospitalised patients with HFMD to participate in our study. After the baseline investigation is completed, we will conduct long-term follow-up of the enrolled cases. In the coming year, we expect to obtain preliminary data on the incidence of sequelae in patients with HFMD 1-10 years after discharge, as well as information on the occurrence of sequelae. This dataset will be updated and expanded on an annual basis to support the continuous monitoring of patient health and disease progression. From HNHFMDCS, the study will provide a comprehensive overview of the potential harm caused by this common infectious disease, assess the social burden caused by this disease and make recommendations for the rehabilitation of survivors and prevention of further disability.

Single nucleotide polymorphism of Notch1 gene rs3124599 allele is associated with the severity of CVA6-related HFMD in the Chinese Han population

BACKGROUND

There is evidence suggesting that Notch1 signaling pathway contributes to the development of hand, foot, and mouth disease (HFMD); however, the role of Notch1 gene polymorphisms in the severity of coxsackievirus A6 (CVA6)-related HFMD remains unclear. This study aimed to investigate the correlation between Notch1 gene polymorphisms and the severity of CVA6-related HFMD.

METHODS

A total of 196 patients (Chinese Han population) diagnosed with CVA6-related HFMD through nucleic acid testing were included in this study. Among them, 97 patients were classified as severe cases, while 99 cases were categorized as mild. The mRNA levels of Notch1 in the peripheral blood leukocytes of HFMD patients were detected by quantitative real-time polymerase chain reaction (qRT-PCR), and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was utilized for genotyping of rs3124599, rs3124603, and rs3124591.

RESULTS

The frequencies of rs3124599 alleles were G (39.0%) and A (61.0%), while the frequencies of rs3124599 genotypes were GG (12.2%), GA (53.6%), and AA (34.2%), respectively. In the recessive model, the frequency of rs3124599 AA genotypes significantly increased in severe patients, compared to mild patients (P < 0.05). Due to the low frequency of alleles for rs3124591 and rs3124603 in patients, as well as the absence of any difference in their distribution between the two groups (P > 0.05), no additional statistical analysis was performed. After adjusting for age and sex, patients with rs3124599 AA genotype had a significantly higher risk of severe HFMD in comparison to G allele carriers (GA/GG), with an odds ratio (95% confidence interval) of 2.010 (1.094, 3.691). Meanwhile, the mRNA levels of Notch1 were found to be significantly higher in severe patients compared to mild patients (P < 0.05), and a positive correlation was observed between Notch1 mRNA levels and the peripheral blood monocyte count (r = 0.42, P < 0.001). Additionally, there were significant differences observed in Notch1 mRNA levels and peripheral blood monocyte counts between patients with the AA genotype of rs3124599 and those with the GA genotype or G allele carriers (P < 0.05).

CONCLUSION

In the Chinese Han population, there is a strong correlation between the Notch1 rs3124599 allele and the severity of CVA6-related HFMD. This correlation may be attributed to genetic polymorphism of rs3124599 regulating Notch1 transcription levels. These findings reveal the important role of Notch1 gene polymorphism in CVA6 infection, establishing a scientific foundation for the precise control of severe HFMD.

Construction of an infectious clone for enterovirus A89 and mutagenesis analysis of viral infection and cell binding

Enterovirus A89 (EV-A89) is an unconventional strain belonging to the Enterovirus A species. Limited research has been conducted on EV-A89, leaving its biological and pathogenic properties unclear. Developing reverse genetic tools for EV-A89 would help to unravel its infection mechanisms and aid in the development of vaccines and anti-viral drugs. In this study, an infectious clone for EV-A89 was successfully constructed and recombinant enterovirus A89 (rEV-A89) was generated. The rEV-A89 exhibited similar characteristics such as growth curve, plaque morphology, and dsRNA expression with parental strain. Four amino acid substitutions were identified in the EV-A89 capsid, which were found to enhance viral infection. Mechanistic studies revealed that these substitutions increased the virus's cell-binding ability. Establishing reverse genetic tools for EV-A89 will significantly contribute to understanding viral infection and developing anti-viral strategies.IMPORTANCEEnterovirus A species contain many human pathogens and have been classified into conventional cluster and unconventional cluster. Most of the research focuses on various conventional members, while understanding of the life cycle and infection characteristics of unconventional viruses is still very limited. In our study, we constructed the infectious cDNA clone and single-round infectious particles for the unconventional EV-A89, allowing us to investigate the biological properties of recombinant viruses. Moreover, we identified key amino acids residues that facilitate EV-A89 infection and elucidate their roles in enhancing viral binding to host cells. The establishment of the reverse genetics system will greatly facilitate future study on the life cycle of EV-A89 and contribute to the development of prophylactic vaccines and anti-viral drugs.