Molecular epidemiology and clinical features of hand, foot and mouth disease requiring hospitalization after the use of enterovirus A71 inactivated vaccine in Chengdu, China, 2017-2022: a descriptive study

A screening study on the detection strain of Coxsackievirus A6: the key to evaluating neutralizing antibodies in vaccines

The increasing incidence of diseases caused by Coxsackievirus A6 (CV-A6) and the presence of various mutants in the population present significant public health challenges. Given the concurrent development of multiple vaccines in China, it is challenging to objectively and accurately evaluate the level of neutralizing antibody response to different vaccines. The choice of the detection strain is a crucial factor that influences the detection of neutralizing antibodies. In this study, the National Institutes for Food and Drug Control collected a prototype strain (Gdula), one subgenotype D1, as well as 13 CV-A6 candidate vaccine strains and candidate detection strains (subgenotype D3) from various institutions and manufacturers involved in research and development. We evaluated cross-neutralization activity using plasma from naturally infected adults (n = 30) and serum from rats immunized with the aforementioned CV-A6 strains. Although there were differences between the geometric mean titer (GMT) ranges of human plasma and murine sera, the overall trends were similar. A significant effect of each strain on the neutralizing antibody test (MAX/MIN 48.0 ∼16410.3) was observed. Among all strains, neutralization of the S112 strain by 15 different sera resulted in higher neutralizing antibody titers (GMTS112 = 132.0) and more consistent responses across different genotypic immune sera (MAX/MIN = 48.0). Therefore, S112 may serve as a detection strain for NtAb testing in various vaccines, minimizing bias and making it suitable for evaluating the immunogenicity of the CV-A6 vaccine.

Effectiveness of EV-A71 Vaccine and Its Impact on the Incidence of Hand, Foot and Mouth Disease: A Systematic Review

BACKGROUND

Vaccination is a highly effective strategy for the prevention of enterovirus A71 (EV-A71)-hand, foot, and mouth disease (HFMD). Three inactivated EV-A71 vaccines in China have demonstrated remarkable efficacy against EV-A71-HFMD during clinical trials, exhibiting vaccine effectiveness (VE) exceeding 90% and few adverse events (AEs). However, the effectiveness of vaccines in the real world and its impact on the epidemiological characteristics of HFMD after the use of EV-A71 inactivated vaccine are uncertain.

METHODS

The odd ratio (OR) and 95% confidence (CI) were used as the effect estimates of the meta-analysis in the test-negative design (TND), and the OR was used to calculate VE: VE = (1 - OR) × 100%.

RESULTS

According to the literature search strategy, a comprehensive search was conducted in PubMed, Web of Science (including Chinese Science Citation Database and MEDLINE), and Embase, and 18 records were ultimately included in this study. Subsequently, the overall VE and 95% CI of different vaccine doses were analyzed, with the one-dose vaccine at 66.9% (95% CI: 45.2-80.0%) and the two-dose vaccine at 84.2% (95% CI: 79.4-87.9%). Additionally, the most reported AEs were mild general reactions without any rare occurrences. Simultaneously, the widespread use of the EV-A71 vaccine would lead to a reduction in both the incidence of EV-A71-associated HFMD and severe cases caused by EV-A71.

CONCLUSION

The administration of the two-dose EV-A71 vaccine is highly effective in preventing HFMD in the real world, and the widespread use of the EV-A71 vaccine leads to a reduction in the incidence of EV-A71-associated HFMD and that of severe cases caused by EV-A71. The findings suggest that administering the two-dose EV-A71 inactivated vaccine to children aged 6 months to 71 months can be effective in preventing EV-A71-associated HFMD, highlighting the need for developing a multivalent HFMD vaccine for preventing cases not caused by EV-A71.

Epidemiology of Enterovirus Genotypes in Association with Human Diseases

Enteroviruses (EVs) are well-known causes of a wide range of infectious diseases in infants and young children, ranging from mild illnesses to severe conditions, depending on the virus genotypes and the host's immunity. Recent advances in molecular surveillance and genotyping tools have identified over 116 different human EV genotypes from various types of clinical samples. However, the current knowledge about most of these genotypes, except for those of well-known genotypes like EV-A71 and EV-D68, is still limited due to a lack of comprehensive EV surveillance systems. This limited information makes it difficult to understand the true burden of EV-related diseases globally. Furthermore, the specific EV genotype associated with diseases varies according to country, population group, and study period. The same genotype can exhibit different epidemiological features in different areas. By integrating the data from established EV surveillance systems in the USA, Europe, Japan, and China, in combination with other EV infection studies, we can elaborate a better understanding of the distribution of prevalent EV genotypes and the diseases associated with EV. This review analyzed the data from various EV surveillance databases and explored the EV seroprevalence and the association of specific EV genotypes with human diseases.

Progress in research and development of preventive vaccines for children in China

The infant and child stage is an important stage for the continuation and development of human society. The initial years of life have a lasting impact on a child's future. Children under the age of 5 have an immature immune system, especially infants and young children under 6 months of age. At this stage, the population has a low immunity to pathogen infections, making them vulnerable to bacteria and viruses. Vaccination can enhance the immunity of infants and children to specific diseases, reduce the transmission rate of infectious diseases, and promote the development of global public health. This article summarizes the current application status of Rotavirus (RV) vaccine, Hand-foot -mouth disease (HFMD) vaccine, and Pneumococcal Conjugate Vaccine (PCV) in China, as well as the research progress of clinical trial vaccine, laying a foundation for subsequent vaccine development.

The Milk of Cows Immunized with Trivalent Inactivated Vaccines Provides Broad-Spectrum Passive Protection against Hand, Foot, and Mouth Disease in Neonatal Mice

Hand, foot, and mouth disease (HFMD) is a contagious viral infection predominantly affecting infants and young children, caused by multiple enteroviruses, including Enterovirus 71 (EV71), Coxsackievirus A16 (CA16), Coxsackievirus A10 (CA10), and Coxsackievirus A6 (CA6). The high pathogenicity of HFMD has garnered significant attention. Currently, there is no specific treatment or broad-spectrum preventive measure available for HFMD, and existing monovalent vaccines have limited impact on the overall incidence or prevalence of the disease. Consequently, with the emergence of new viral strains driven by vaccine pressure, there is an urgent need to develop strategies for the rapid response and control of new outbreaks. In this study, we demonstrated the broad protective effect of maternal antibodies against three types of HFMD by immunizing mother mice with a trivalent inactivated vaccine targeting EV71, CA16, and CA10, using a neonatal mouse challenge model. Based on the feasibility of maternal antibodies as a form of passive immunization to prevent HFMD, we prepared a multivalent antiviral milk by immunizing dairy cows with the trivalent inactivated vaccine to target multiple HFMD viruses. In the neonatal mouse challenge model, this immunized milk exhibited extensive passive protection against oral infections caused by the three HFMD viruses. Compared to vaccines, this strategy may offer a rapid and broadly applicable approach to providing passive immunity for the prevention of HFMD, particularly in response to the swift emergence and spread of new variants.

Effectiveness of enterovirus A71 vaccine against pediatric HFMD and disease profile of post-vaccination infection

BACKGROUND

Vaccination has been proven effective against infection with enterovirus A71 (EV-A71) in clinical trials, but vaccine effectiveness in real-world situations remains incompletely understood. Furthermore, it is not clear whether previous vaccination will result in symptom attenuation among post-vaccinated cases.

METHODS

Based on long-term data extracted from the only designed referral hospital for infectious diseases, we used a test-negative case-control design and multivariate logistic regression models to analyze the effectiveness of EV-A71 vaccine against hand, foot and mouth disease (HFMD). And then, generalized linear regression models were used to evaluate the associations between prior vaccination and disease profiles.

RESULTS

We selected 4883 inpatients for vaccine efficacy estimations and 2188 inpatients for disease profile comparisons. Vaccine effectiveness against EV-A71-induced HFMD for complete vaccination was 63.4 % and 51.7 % for partial vaccination. The vaccine effectiveness was higher among cases received the first dose within 12 months. No protection was observed against coxsackievirus (CV) A6-, CV-A10- or CV-A16-associated HFMD among children regardless of vaccination status. Completely vaccinated cases had shorter hospital stay and disease course compared to unvaccinated cases (P < 0.05).

CONCLUSIONS

These findings reiterate the need to continue the development of a multivalent vaccine or combined vaccines, and have implications for introducing optimized vaccination strategies.

Resveratrol inhibits respiratory syncytial virus replication by targeting heparan sulfate proteoglycans

Resveratrol, renowned as an antioxidant, also exhibits significant potential in combatting severe respiratory infections, particularly the respiratory syncytial virus (RSV). Nevertheless, the specific mechanism underlying its inhibition of RSV replication remains unexplored. Heparan sulfate proteoglycans (HSPGs) play a pivotal role as attachment factors for numerous viruses, offering a promising avenue for countering viral infections. Our research has unveiled that resveratrol effectively curbs RSV infection in a dose-dependent manner. Remarkably, resveratrol disrupts the early stages of RSV infection by engaging with HSPGs, rather than interacting with RSV surface proteins like fusion (F) protein and glycoprotein (G). Resveratrol's affinity appears to be predominantly directed towards the negatively charged sites on HSPGs, thus impeding the binding of viral receptors. In an in vivo study involving RSV-infected mice, resveratrol demonstrates its potential by ameliorating pulmonary pathology. This improvement is attributed to the inhibition of pro-inflammatory cytokine expression and a reduction in viral load within the lungs. Notably, resveratrol specifically alleviates inflammation characterized by an abundance of neutrophils in RSV-infected mice. In summation, our data first shows how resveratrol combats RSV infection through interactions with HSPGs, positioning it as a promising candidate for innovative drug development targeting RSV infections. Our study provides insight into the mechanism of resveratrol antiviral infection.

Circulating trends of hand, foot, and mouth disease in Hubei Province, China: Impact from the COVID-19 pandemic

Objectives

This study was performed to investigate the effect of non-pharmaceutical interventions on hand, foot, and mouth disease in Hubei Province China during the coronavirus disease 2019 pandemic.

Methods

Data and samples were collected from the hand, foot, and mouth disease surveillance laboratory network in Hubei Province between 2018 and 2022. The samples were identified as Enterovirus A71, Coxsackievirus A6or Coxsackievirus A16 via real-time polymerase chain reaction. Representative Coxsackievirus A6 and Coxsackievirus A16 samples were sequenced and subjected to phylogenetic analyses.

Results

A noticeable 3-fold reduction in the number of hand, foot, and mouth disease cases was observed from 2019 to 2020. The age and sex distributions of patients with hand, foot, and mouth disease were approximately the same from 2018 to 2022. The proportion of Coxsackievirus A6 accounted for 86 % in 2020 and 75 % in 2021 for hand, foot, and mouth disease compared with 48 % in 2018, 53 % in 2019, and 29 % in 2022. The proportions of Coxsackievirus A16 in 2020 and 2021 were 2 % and 17 %, respectively, showing a sharp decline in 2018 (37.8 %) and 2019 (35 %). In 2022, Coxsackievirus A16 was the dominant serotype (46 %). Only slight differences were found in the VP1 sequences across the different years.

Conclusions

Our study confirmed that a series of non-pharmaceutical interventions during the coronavirus disease 2019 period reduced the transmission of enteroviruses and that long-term restrictions could significantly change the prevalence of enterovirus serotypes causing hand, foot, and mouth disease.

VP2 residue N142 of coxsackievirus A10 is critical for the interaction with KREMEN1 receptor and neutralizing antibodies and the pathogenicity in mice

Coxsackievirus A10 (CVA10) has recently emerged as one of the major causative agents of hand, foot, and mouth disease. CVA10 may also cause a variety of complications. No approved vaccine or drug is currently available for CVA10. The residues of CVA10 critical for viral attachment, infectivity and in vivo pathogenicity have not been identified by experiment. Here, we report the identification of CVA10 residues important for binding to cellular receptor KREMEN1. We identified VP2 N142 as a key receptor-binding residue by screening of CVA10 mutants resistant to neutralization by soluble KREMEN1 protein. The receptor-binding residue N142 is exposed on the canyon rim but highly conserved in all naturally occurring CVA10 strains, which provides a counterexample to the canyon hypothesis. Residue N142 when mutated drastically reduced receptor-binding activity, resulting in decreased viral attachment and infection in cell culture. More importantly, residue N142 when mutated reduced viral replication in limb muscle and spinal cord of infected mice, leading to lower mortality and less severe clinical symptoms. Additionally, residue N142 when mutated could decrease viral binding affinity to anti-CVA10 polyclonal antibodies and a neutralizing monoclonal antibody and render CVA10 resistant to neutralization by the anti-CVA10 antibodies. Overall, our study highlights the essential role of VP2 residue N142 of CVA10 in the interactions with KREMEN1 receptor and neutralizing antibodies and viral virulence in mice, facilitating the understanding of the molecular mechanisms of CVA10 infection and immunity. Our study also provides important information for rational development of antibody-based treatment and vaccines against CVA10 infection.

Molecular epidemiology and clinical characteristics of enteroviruses associated HFMD in Chengdu, China, 2013-2022

OBJECTIVES

This study aims to investigate molecular epidemiology and clinical characteristics of enterovirus associated hand-foot-mouth disease (HFMD) in Chengdu, China, 2013-2022. Monitoring the molecular epidemiology and clinical features of HFMD for up to 10 years may provide some ideas for future protection and control measures.

METHODS

We conducted a retrospective analysis of the medical records of all patients with laboratory-confirmed HFMD-related enterovirus infection at the West China Second University Hospital from January 2013 to December 2022. We described the characteristics in serotype, age, sex distribution and hospitalization of enterovirus infection cases using data analysis and graphic description.

RESULTS

A total of 29,861 laboratory-confirmed cases of HFMD-related enterovirus infection were reported from 2013 to 2022. There was a significant reduction in the number and proportion of EV-A71 cases after 2016, from 1713 cases (13.60%) in 2013-2015 to 150 cases (1.83%) in 2017-2019. During the COVID-19 pandemic, EV-A71 cases even disappeared. The proportion of CV-A16 cases decreased from 13.96% in 2013-2015 to 10.84% in 2017-2019 and then to 4.54% in 2020-2022. Other (non-EV-A71 and non-CV-A16) serotypes accounted for 95.45% during 2020-2022, with CV-A6 accounting for 50.39% and CV-A10 accounting for 10.81%. Thus, CV-A6 and CV-A10 became the main prevalent serotypes. Furthermore, There was no significant difference in the enterovirus prevalence rate between males and females. The hospitalization rate of EV-A71 patients was higher that of other serotypes. In general, the proportion of HFMD hospitalizations caused by other pathogens except for EV-A71, CV-A16, CV-A10 and CV-A16 was second only to that caused by EV-A71. The proportion of children over 4 years old infected with enterovirus increased.

CONCLUSION

The incidence of HFMD associated with enterovirus infection has decreased significantly and CV-A6 has been the main pathogen of HFMD in Chengdu area in recent years. The potential for additional hospitalizations for other untested enterovirus serotypes suggested that attention should also be paid to the harms of infections with unknown enterovirus serotypes. Children with HFMD were older. The development of new diagnostic reagents and vaccines may play an important role in the prevention and control of enterovirus infection.

Epidemiology of hand, foot and mouth disease and genomic surveillance of coxsackievirus A10 circulating in Zhejiang Province, China during 2017 to 2022

BACKGROUND

Coxsackievirus A10 (CA10) is one of the etiological agents associated with hand, foot and mouth disease (HFMD).

OBJECTIVES

We aimed to perform a retrospective analysis of the molecular epidemiological characteristics and genetic features of HFMD associated with CA10 infections in Zhejiang Province from 2017 to 2022.

STUDY DESIGN

Epidemiologic features were summarized. Throat swab specimens were collected and tested. The VP1 regions were sequenced for genotyping. CA10 positive samples were isolated. Whole genomes of CA10 isolations were sequenced. Nucleotide and amino acid changes were characterized. Phylogenetic trees were constructed.

RESULTS

The number of HFMD cases fluctuated from 2017 to 2022. Children aged below 3 years accounted for the majority (66.29%) and boys were more frequently affected than girls. Cases peaked in June. The positivity rate of HEV was 62.69%. A total of 90 strains of CA10 were isolated and 53 genomes were obtained. All CA10 in this study could be assigned to two genogroups, C (C2) and F (F1 and F3).

CONCLUSION

The clinical manifestations of HFMD associated with HEV are complex and diverse. CA10 infection may be emerging as a new and major cause of HFMD because an upward trend was observed in the proportion of CA10 cases after the use of EV71 vaccines. Different genogroups of CA10 had different geographic distribution patterns. Surveillance should be strengthened and further comprehensive studies should be continued to provide a scientific basis for HFMD prevention and control.

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.