Search Results (12)

Background: The three commercial Enterovirus 71 (EV71) inactivated vaccines which have effectively controlled the EV71 pandemic currently rely on inherent variable in vivo potency methods for batch release. To align with 3R (Replacement, Reduction, Refinement) principles and enhance quality control, this study referred to WHO guidelines and the European Pharmacopoeia to develop in vitro relative potency (IVRP) methods. Methods: Working standards tracing to phase 3 clinical vaccines were established. Manufacture-specific IVRP methods were developed and validated per ICH Q14/Q2(R2), utilizing conformational epitope-targeting neutralizing monoclonal antibodies (MAbs). One of the MAbs (CT11F9) recognition sites was clarified with Cryo-EM. Subsequently, the performance of IVRP was assessed using varied concentrations and heat-treated vaccines. The correlation between IVRP and in vivo methods was analyzed, followed by setting IVRP specifications. Results: The manufacturer-specific working standard exhibited ED50 values comparable to those of related phase 3 clinical vaccines. All IVRP methods achieved a relative bias/precision/total error ≤ 15%. The IVRP methods correlated with in vivo methods (p < 0.05, r > 0.9) can discriminate EV71 antigen concentrations (p < 0.01, r > 0.99) and indicate the stability of the vaccines. Cryo-EM was adopted to identify the epitopes recognized by CT11F9, revealing that this neutralizing antibody recognizes a conformational epitope spanning VP1-3 of the same protomer. Using 31–47 batches of commercial vaccines, IVRP specifications were proposed as 0.56–1.35, 0.58–1.40, and 0.54–1.50. Conclusions: Based on conformational epitope-targeting neutralizing MAbs, manufacturer-specific IVRP methods, which were sensitive to process variations and correlated with in vivo results, have been established. IVRP methods provide a reliable, animal-free alternative for EV71 vaccine batch release. Full article

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. Full article

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. Full article

Coxsackievirus A10 (CVA10) causes hand, foot, and mouth disease (HFMD) and herpangina, which can result in severe neurological symptoms in children. CVA10 does not use the common enterovirus 71 (EV71) receptor, human SCARB2 (hSCARB2, scavenger receptor class B, member 2), for infection but instead uses another receptor, such as KREMEN1. Our research has shown that CVA10 can infect and replicate in mouse cells expressing human SCARB2 (3T3-SCARB2) but not in the parental NIH3T3 cells, which do not express hSCARB2 for CVA10 entry. Knocking down endogenous hSCARB2 and KREMEN1 with specific siRNAs inhibited CVA10 infection in human cells. Co-immunoprecipitation confirmed that VP1, a main capsid protein where virus receptors for attaching to the host cells, could physically interact with hSCARB2 and KREMEN1 during CVA10 infection. It is the efficient virus replication following virus attachment to its cellular receptor. It resulted in severe limb paralysis and a high mortality rate in 12-day-old transgenic mice challenged with CVA10 but not in wild-type mice of the same age. Massive amounts of CVA10 accumulated in the muscles, spinal cords, and brains of the transgenic mice. Formalin inactivated CVA10 vaccine-induced protective immunity against lethal CVA10 challenge and reduced the severity of disease and tissue viral loads. This is the first report to show that hSCARB2 serves as an associate to aid CVA10 infection. hSCARB2-transgenic mice could be useful in evaluating anti-CVA10 medications and studying the pathogenesis induced by CVA10. Full article

Background: The aim of this study was to investigate the immunogenicity and safety of the enterovirus 71 vaccine (EV71 vaccine) administered alone or simultaneously. Methods: A multi-center, open-label, randomized controlled trial was performed involving 1080 healthy infants aged 6 months or 8 months from Shandong, Shanxi, Shaanxi, and Hunan provinces. These infants were divided into four simultaneous administration groups and EV71 vaccine separate administration group. Blood samples were collected from the infants before the first vaccination and after the completion of the vaccination. This trial was registered in the Clinical Trials Registry (NCT03519568). Results: A total of 895 were included in the per-protocol analysis. The seroconversion rates of antibodies against EV71 in four simultaneous administration groups (98.44% (189/192), 94.57% (122/129), 99.47% (187/188) and 98.45% (190/193)) were non-inferior to EV71 vaccine separate administration group (97.93% [189/193]) respectively. Fever was the most common adverse event, the pairwise comparison tests showed no difference in the incidence rate of solicited, systemic or local adverse events. Three serious adverse events related to the vaccination were reported. Conclusions: The evidence of immunogenicity and safety supports that the EV71 vaccine administered simultaneously with vaccines need to be administered during the same period of time recommended in China. Full article

Hand, foot, and mouth disease (HFMD) commonly produces herpangina, but fatal neurological complications have been observed in children. Enterovirus 71 (EV-A71) and Coxsackievirus 16 (CV-A16) are the predominant viruses causing HFMD worldwide. With rising concern about HFMD outbreaks, there is a need for an effective vaccine against EV-A71 and CV-A16. Although an inactivated vaccine has been developed against EV-A71 in China, the inability of the inactivated vaccine to confer protection against CV-A16 infection and other HFMD etiological agents, such as CV-A6 and CV-A10, necessitates the exploration of other vaccine platforms. Thus, the antigenic peptide-based vaccines are promising platforms to develop safe and efficacious multivalent vaccines, while the monoclonal antibodies are viable therapeutic and prophylactic agents against HFMD etiological agents. This article reviews the available information related to the antigenic peptides of the etiological agents of HFMD and their neutralizing antibodies that can provide a basis for the design of future therapies against HFMD etiological agents. Full article

Enterovirus 71 (EV71) infections have a major public health impact in the Asia-Pacific region. We reviewed the epidemiology, pathogenesis, and molecular epidemiology of EV71 infection as well as EV71 vaccine development. Previous studies were found using the search terms “enterovirus 71” and “epidemiology” or “pathogenesis” or “molecular epidemiology” or “vaccine” in Medline and PubMed. Articles that were not published in the English language, manuscripts without an abstract, and opinion articles were excluded from the review. The reported epidemiology of cases caused by EV71 infection varied from country to country; seasonal variations in incidence were observed. Most cases of EV71 infection that resulted in hospitalization for complications occurred in children less than five years old. The brainstem was the most likely major target of EV71 infection. The emergence of the EV71 epidemic in the Asia-Pacific region has been associated with the circulation of different genetic lineages (genotypes B3, B4, C1, C2, and C4) that appear to be undergoing rapid evolutionary changes. The relationship between the gene structure of the EV71 virus and the factors that ensure its survival, circulation, and evasion of immunity is still unknown. EV71 infection has emerged as an important global public health problem. Vaccine development, including the development of inactivated whole-virus live attenuated, subviral particles, and DNA vaccines, has been progressing. Full article

The hand, foot and mouth disease is caused by a group of Enteroviruses such as Enterovirus 71 (EV-A71) and Coxsackievirus CV-A5, CV-A8, and CV-A16. Mild symptoms of EV-A71 infection in children range from high fever, vomiting, rashes and ulcers in mouth but can produce more severe symptoms such as brainstem and cerebellar encephalitis, leading up to cardiopulmonary failure and death. The lack of vaccines and antiviral drugs against EV-A71 highlights the urgency of developing preventive and treatment agents against EV-A71 to prevent further fatalities. Research groups have developed experimental inactivated vaccines, recombinant Viral Protein 1 (VP1) vaccine and virus-like particles (VLPs). The inactivated EV-A71 vaccine is considered the safest viral vaccine, as there will be no reversion to the infectious wild type strain. The recombinant VP1 vaccine is a cost-effective immunogen, while VLPs contain an arrangement of epitopes that can elicit neutralizing antibodies against the virus. As each type of vaccine has its advantages and disadvantages, increased studies are required in the development of such vaccines, whereby high efficacy, long-lasting immunity, minimal risk to those vaccinated, safe and easy production, low cost, dispensing the need for refrigeration and convenient delivery are the major goals in their design. Full article

Enterovirus 71 (EV71) is a group of viruses that belongs to the Picornaviridae family, which also includes viruses such as polioviruses. EV71, together with coxsackieviruses, is widely known for its association with Hand Foot Mouth Disease (HFMD), which generally affects children age five and below. Besides HFMD, EV71 can also trigger more severe and life-threatening neurological conditions such as encephalitis. Considering the lack of a vaccine and antiviral drug against EV71, together with the increasing spread of these viruses, the development of such drugs and vaccines becomes the top priority in protecting our younger generations. This article, hence, reviews some of the recent progress in the formulations of anti-therapeutics and vaccine generation for EV71, covering (i) inactivated vaccines; (ii) baculovirus-expressed vaccines against EV71; (iii) human intravenous immunoglobulin (IVIg) treatment; and (iv) the use of monoclonal antibody therapy as a prevention and treatment for EV71 infections. Full article

Hand, foot, and mouth disease (HFMD) has recently emerged as a major public health concern across the Asian-Pacific region. Enterovirus 71 (EV71) and Coxsackievirus A16 (CVA16) are the primary causative agents of HFMD, but other members of the Enterovirus A species, including Coxsackievirus A6 (CVA6), can cause disease. The lack of small animal models for these viruses have hampered the development of a licensed HFMD vaccine or antivirals. We have previously reported on the development of a mouse model for EV71 and demonstrated the protective efficacy of an inactivated EV71 vaccine candidate. Here, mouse-adapted strains of CVA16 and CVA6 were produced by sequential passage of the viruses through mice deficient in interferon (IFN) α/β (A129) and α/β and γ (AG129) receptors. Adapted viruses were capable of infecting 3 week-old A129 (CVA6) and 12 week-old AG129 (CVA16) mice. Accordingly, these models were used in active and passive immunization studies to test the efficacy of a trivalent vaccine candidate containing inactivated EV71, CVA16, and CVA6. Full protection from lethal challenge against EV71 and CVA16 was observed in trivalent vaccinated groups. In contrast, monovalent vaccinated groups with non-homologous challenges failed to cross protect. Protection from CVA6 challenge was accomplished through a passive transfer study involving serum raised against the trivalent vaccine. These animal models will be useful for future studies on HFMD related pathogenesis and the efficacy of vaccine candidates. Full article

Coxsackievirus A16 (CA16) and enterovirus 71 (EV71), both of which can cause hand, foot and mouth disease (HFMD), are responsible for large epidemics in Asian and Pacific areas. Although inactivated EV71 vaccines have completed testing in phase III clinical trials in Mainland China, CA16 vaccines are still under development. A Vero cell-based inactivated CA16 vaccine was developed by our group. Screening identified a CA16 vaccine strain (CC024) isolated from HFMD patients, which had broad cross-protective abilities and satisfied all requirements for vaccine production. Identification of the biological characteristics showed that the CA16CC024 strain had the highest titer (10^7.5 CCID50/mL) in Vero cells, which would benefit the development of an EV71/CA16 divalent vaccine. A potential vaccine manufacturing process was established, including the selection of optimal time for virus harvesting, membrane for diafiltration and concentration, gel-filtration chromatography for the down-stream virus purification and virus inactivation method. Altogether, the analyses suggested that the CC-16, a limiting dilution clone of the CC024 strain, with good genetic stability, high titer and broad-spectrum immunogenicity, would be the best candidate strain for a CA16 inactivated vaccine. Therefore, our study provides valuable information for the development of a Vero cell-based CA16 or EV71-CA16 divalent inactivated vaccine. Full article

Enterovirus 71 (EV71) is a notable causative agent of hand, foot, and mouth disease in children, which is associated with an increased incidence of severe neurological disease and death, yet there is no specific treatment or vaccine for EV71 infections. In this study, the antiviral activity of gramine and 21 gramine derivatives against EV71 was investigated in cell-based assays. Eighteen derivatives displayed some degree of inhibitory effects against EV71, in that they could effectively inhibit virus-induced cytopathic effects (CPEs), but the anti-EV71 activity of the lead compound gramine was not observed. Studies on the preliminary modes of action showed that these compounds functioned by targeting the early stage of the EV71 lifecycle after viral entry, rather than inactivating the virus directly, inhibiting virus adsorption or affecting viral release from the cells. Among these derivatives, one (compound 4s) containing pyridine and benzothiazole units showed the most potency against EV71. Further studies demonstrated that derivative 4s could profoundly inhibit viral RNA replication, protein synthesis, and virus-induced apoptosis in RD cells. These results indicate that derivative 4s might be a feasible therapeutic agent against EV71 infection and that these gramine derivatives may provide promising lead scaffolds for the further design and synthesis of potential antiviral agents. Full article