Recent advances of enterovirus 71 [Formula: see text] targeting Inhibitors.

With CA16, enterovirus-71 is the causative agent of hand foot and mouth disease (HFMD) which occurs mostly in children under 5 years-old and responsible of several outbreaks since a decade. Most of the time, HFMD is a mild disease but can progress to severe complications such as meningitis, brain stem encephalitis, acute flaccid paralysis (AFP) and even death; EV71 has been identified in all severe cases. Therefore, it is actually one of the most public health issues that threatens children's life. [Formula: see text] is a protease which plays important functions in EV71 infection. To date, a lot of [Formula: see text] inhibitors have been tested but none of them has been approved yet. Therefore, a drug screening is still an utmost importance in order to treat and/or prevent EV71 infections. This work highlights the EV71 life cycle, [Formula: see text] functions and [Formula: see text] inhibitors recently screened. It permits to well understand all mechanisms about [Formula: see text] and consequently allow further development of drugs targeting [Formula: see text]. Thus, this review is helpful for screening of more new [Formula: see text] inhibitors or for designing analogues of well known [Formula: see text] inhibitors in order to improve its antiviral activity.

Salvianolic Acid B Inhibits Hand-Foot-Mouth Disease Enterovirus 71 Replication through Enhancement of AKT Signaling Pathway.

Hand, foot, and mouth disease (HFMD) is caused by enterovirus 71 (EV71) in infants and children under six years of age. HFMD is characterized by fever, mouth ulcers, and vesicular rashes on the palms and feet. EV71 also causes severe neurological manifestations, such as brainstem encephalitis and aseptic meningitis. Recently, frequent outbreaks of EV71 have occurred in the Asia-Pacific region, but currently, no effective antiviral drugs have been developed to treat the disease. In this study, we investigated the antiviral effect of salvianolic acid B (SalB) on EV71. SalB is a major component of the Salvia miltiorrhiza root and has been shown to be an effective treatment for subarachnoid hemorrhages and myocardial infarctions. HeLa cells were cultured in 12-well plates and treated with SalB (100 or 10 µg/ml) and 106 PFU/ml of EV71. SalB treatment (100 µg/ml) significantly decreased the cleavage of the eukaryotic eIF4G1 protein and reduced the expression of the EV71 capsid protein VP1. In addition, SalB treatment showed a dramatic decrease in viral infection, measured by immunofluorescence staining. The Akt signaling pathway, a key component of cell survival and proliferation, was significantly increased in EV71-infected HeLa cells treated with 100 µg/ml SalB. RT-PCR results showed that the mRNA for anti-apoptotic protein Bcl-2 and the cell cycle regulator Cyclin-D1 were significantly increased by SalB treatment. These results indicate that SalB activates Akt/PKB signaling and inhibits apoptosis in infected HeLa cells. Taken together, these results suggest that SalB could be used to develop a new therapeutic drug for EV71-induced HFMD.

Virucidal activity and the antiviral mechanism of acidic polysaccharides against Enterovirus 71 infection in vitro.

Enterovirus 71 (EV71) is the predominant pathogen for severe hand, foot, and mouth disease (HFMD) in children younger than 5 years, and currently no effective drugs are available for EV71. Thus, there is an urgent need to develop new drugs for the control of EV71 infection. In this study, LJ04 was extracted from Laminaria japonica using diethylaminoethyl cellulose-52 with 0.4 mol/l NaCl as the eluent, and its virucidal activity was evaluated based on its cytopathic effects on a microplate. LJ04 is composed of fucose, galactose, and mannose and mainly showed good virucidal activity against EV71. The antiviral mechanisms of LJ04 were the direct inactivation of the virus, the blockage of virus binding, disruptions to viral entry, and weak inhibitory activity against the nonstructural protein 3C. The two most important findings from this study were that LJ04 inhibited EV71 proliferation in HM1900 cells, which are a human microglia cell line, and that LJ04 can directly inactivate EV71 within 2 hr at 37°C. This study demonstrates for the first time the ability of a polysaccharide from L. japonica to inhibit viral and 3C activity; importantly, the inhibition of 3C might have a minor effect on the antiviral effect of LJ04. Consequently, our results identify LJ04 as a potential drug candidate for the control of severe EV71 infection in clinical settings.

Reversible Cerebral Angiopathy after Viral Infection in a Pediatric Patient with Genetic Variant of RNF213.

Ring finger protein (RNF) 213 is known as a susceptibility gene for moyamoya disease (MMD), which is characterized by bilateral carotid folk stenosis. Cerebral angiopathy after viral infection has been known to present angiographical appearance resembling MMD, however its pathogenesis and genetic background are not well known. We report a case of reversible cerebral angiopathy after viral infection in a pediatric patient with genetic variant of RNF213 mutation. The patient had developed a severe headache after hand, foot, and mouth disease. Magnetic resonance imaging and magnetic resonance angiography (MRA) performed 2-3 weeks after disease onset revealed bilateral carotid folk stenosis and an old cerebral infarction in the left putamen. The patient's headache spontaneously resolved and the follow-up MRA showed a complete spontaneous resolution of the arterial stenosis after 9 months. We were able to determine genetic predisposition to angiopathy by identifying the RNF213 c.14576G>A (rs112735431, p.R4859K) mutation. Based on the present case, we hypothesize that an RNF213 variant might play an important role for the onset of postviral cerebral angiopathy.

Pattern Classification of Enterovirus 71-Associated Hand, Foot, and Mouth Disease in Chinese Medicine: A Retrospective Study in 433 Cases.

OBJECTIVE: To determine whether patterns of enterovirus 71 (EV71)-associated hand, foot, and mouth disease (HFMD) were classified based on symptoms and signs, and explore whether individual characteristics were correlated with membership in particular pattern. METHODS: Symptom-based latent class analysis (LCA) was used to determine whether patterns of EV71-HFMD existed in a sample of 433 cases from a clinical data warehouse system. Logistic regression was then performed to explore whether demographic, and laboratory data were associated with pattern membership. RESULTS: LCA demonstrated a two-subgroup solution with an optimal fit, deduced according to the Bayesian Information Criterion minima. Hot pattern (59.1% of all patients) was characterized by a very high fever and high endorsement rates for classical HFMD symptoms (i.e., rash on the extremities, blisters, and oral mucosa lesions). Non-hot pattern (40.9% of all patients) was characterized by classical HFMD symptoms. The multiple logistic regression results suggest that white blood cell counts and aspartate transaminase were positively correlated with the hot pattern (adjust odds ratio=1.07, 95% confidence interval: 1.006-1.115; adjust odds ratio=1.051, 95% confidence interval: 1.019-1.084; respectively). CONCLUSIONS: LCA on reported symptoms and signs in a retrospective study allowed different subgroups with meaningful clinical correlates to be defined. These findings provide evidence for targeted prevention and treatment interventions.

Efficacy of Scutellaria baicalensis for the Treatment of Hand, Foot, and Mouth Disease Associated with Encephalitis in Patients Infected with EV71: A Multicenter, Retrospective Analysis.

This study aimed to evaluate the clinical efficacy and safety of using the traditional Chinese herbal medicine Scutellaria baicalensis for the treatment of severe HFMD in 725 patients aged >1 year in a multicenter, retrospective analysis. The patients were divided into the S. baicalensis and ribavirin groups, and the temperatures, presence or absence of skin rashes and oral lesions, nervous system (NS) involvement, and viral loads of the patients, as well as the safety of the treatments, were evaluated. The median duration of fever, median time to NS involvement, and the number of patients with oral ulcers and/or vesicles, as well as skin rashes, were decreased in the S. baicalensis group compared with the ribavirin group. In addition, the EV71 viral loads were decreased in the S. baicalensis group, suggesting that S. baicalensis exerted more potent antiviral effects compared with ribavirin. The present study demonstrated that S. baicalensis was suitable for the treatment of severe HFMD in patients aged >1 year, since it was shown to rapidly relieve fever, attenuate oral lesions and rashes, and improve NS involvement. Furthermore, it was demonstrated to be relatively safe for topical application.

[Hand, foot and mouth disease--more than a harmless "childhood disease"]. / Hand-fuss-Mund-Krankheit--weit mehr als eine harmlose "Kinderkrankheit".

Hand, foot and mouth disease (HFMD) is a highly contagious, world-wide distributed viral illness that affects predominantly children. It is caused by several enteroviruses, such as coxsackieviruses A6, A10, A16 and enterovirus 71. In most cases, HFMD follows a benign and self-limiting course. After an incubation period of 3 to 10 days, fever and sore throat, the first symptoms of the disease, appear. A few days later, maculopapular or vesicular eruptions form on the palms and soles as well as in the oral cavity. Since the year 2000, several large HFMD outbreaks have been reported in many Asian regions such as China, Malaysia and Vietnam. In some of these outbreaks, high incidences of severe progressive HFMD forms with some fatalities were observed. Such diseases have been caused primarily by enterovirus 71 strains and were characterized frequently by sudden onset of fever, encephalitis/meningitis and severe respiratory symptoms such as pulmonary edema. Further severe neurological and cardiac complications have also been observed during these outbreaks. Recently, some HFMD outbreaks caused by the coxsackievirus A6 have been reported in several parts of the world. These illnesses also affected adults and were characterized by more severe symptoms of "classical" HFMD. In addition, outbreaks of coxsackievirus-A6-associated HFMD in many countries were associated with onychomadesis, with the loss of nails occurring up to two months after initial symptoms. Treatment of "classical" HFMD is usually symptomatic, a generally recommended antiviral therapy does not exist. In severe HFMD cases, suitable treatment also encompasses mechanical ventilation, as well as the additional application of antiviral agents such as ribavirin. In the last years, several novel agents with good in vitro and in vivo activity against enteroviruses have been developed. A vaccine against HFMD is not yet available.

Glycyrrhizic acid as the antiviral component of Glycyrrhiza uralensis Fisch. against coxsackievirus A16 and enterovirus 71 of hand foot and mouth disease.

ETHNOPHARMACOLOGICAL RELEVANCE: The radices of Glycyrrhiza uralensis Fisch. and herbal preparations containing Glycyrrhiza spp. have been used for thousands of years as an herbal medicine for the treatment of viral induced cough, viral hepatitis, and viral skin diseases like ulcers in China. Glycyrrhizic acid (GA) is considered the principal component in Glycyrrhiza spp. with a wide spectrum of antiviral activity. AIM: The present study attempt to validate the medicinal use of Glycyrrhiza uralensis for hand, foot and mouth disease (HFMD) and further to verify whether GA is an active antiviral component in the water extract of Glycyrrhiza uralensis. MATERIALS AND METHODS: Radices of Glycyrrhiza uralensis Fisch. were extracted with hot water. The chemical contents of the extract were profiled with HPLC analysis. The antiviral activity of the extract and the major components was evaluated against infection of enterovirus 71 (EV71) and coxsackievirus A16 (CVA16) on Vero cells. The cytopathic effect caused by the infection was measured with MTT assay. Infectious virion production was determined using secondary infection assays and viral protein expression by immunoblotting analysis. RESULTS: The extract at 1000 µg/ml suppressed EV71 replication by 1.0 log and CVA16 by 1.5 logs. The antiviral activity was associated with the content of GA in the extract since selective depletion of GA from the extract by acid precipitation resulted in loss of antiviral activity. In contrast, the acid precipitant retained antiviral activity. The precipitant at a concentration of 200 µg/ml inhibited EV71 and CVA16 replication by 1.7 and 2.2 logs, respectively. Furthermore, GA dose-dependently blocked viral replication of EV71 and CVA16. At 3 mM, GA reduced infectious CVA16 and EV71 production by 3.5 and 2.2 logs, respectively. At 5mM, CVA16 production was reduced by 6.0 logs and EV71 by 4.0 logs. Both EV71 and CVA16 are members of Enterovirus genus, time-of-drug addition studies however showed that GA directly inactivated CVA16, while GA anti-EV71 effect was associated with an event(s) post virus cell entry. CONCLUSIONS: This study validated the medicinal usefulness of radices Glycyrrhiza uralensis against the etiological agents of HFMD. In addition to the identification of GA as the antiviral component of Glycyrrhiza uralensis against EV71 and CVA16 infection, this study also reveals that GA inhibits EV71 and CVA16 with distinct mechanisms.

Progress on the research and development of human enterovirus 71 (EV71) vaccines.

Enterovirus 71 (EV71) infections, which can cause severe complications, have become one of the serious public health issues in the Western Pacific region and China. To date, a number of pharmaceutical companies and institutes have initiated the research and development of EV71 vaccines as a countermeasure. As is the case with innovative vaccine development, there are several critical bottlenecks in EV71 vaccine development that must be overcome before the clinical trials, including the selection of vaccine strain, standardization of the procedure for quantifying neutralizing antibody (NTAb) and antigen, establishment and application of a reference standard and biological standards, development of animal models for the evaluation of protective efficacy, and identification of the target patient population. To tackle these technical obstacles, researchers in Mainland of China have conducted a series of studies concerning the screening of vaccine strains and the establishment of criteria, biological standards and detection methods, thereby advancing EV71 vaccine development. This review summarizes recent worldwide progress on the quality control and evaluation of EV71 vaccines.