Coxsackievirus B3 HFMD animal models in Syrian hamster and rhesus monkey

Coxsackievirus B3 (CVB3) is the pathogen causing hand, foot and mouth disease (HFMD), which manifests across a spectrum of clinical severity from mild to severe. However, CVB3-infected mouse models mainly demonstrate viral myocarditis and pancreatitis, failing to replicate human HFMD symptoms. Although several enteroviruses have been evaluated in Syrian hamsters and rhesus monkeys, there is no comprehensive data on CVB3. In this study, we have first tested the susceptibility of Syrian hamsters to CVB3 infection via different routes. The results showed that Syrian hamsters were successfully infected with CVB3 by intraperitoneal injection or nasal drip, leading to nasopharyngeal colonization, acute severe pathological injury, and typical HFMD symptoms. Notably, the nasal drip group exhibited a longer viral excretion cycle and more severe pathological damage. In the subsequent study, rhesus monkeys infected with CVB3 through nasal drips also presented signs of HFMD symptoms, viral excretion, serum antibody conversion, viral nucleic acids and antigens, and the specific organ damages, particularly in the heart. Surprisingly, there were no significant differences in myocardial enzyme levels, and the clinical symptoms resembled those often associated with common, mild infections. In summary, the study successfully developed severe Syrian hamsters and mild rhesus monkey models for CVB3-induced HFMD. These models could serve as a basis for understanding the disease pathogenesis, conducting pre-trial prevention and evaluation, and implementing post-exposure intervention.

Clinical profile and molecular typing of viral etiological agents associated with Hand, Foot and Mouth Disease (HFMD): A study from Udhampur, Northern India

PURPOSE

Hand, Foot and Mouth disease (HFMD) is a contagious pediatric viral disease caused due to enteroviruses (EV) of the family Picornaviridae. Cases of HFMD were reported from a tertiary care health centre, Udhampur, (Jammu and Kashmir), Northern India. The present study highlights the clinical and molecular virological aspects of HFMD cases.

MATERIAL AND METHODS

Cases reported during August 2016-September 2017, and clinically diagnosed as HFMD of all age groups were included. Clinical, Biochemical and molecular virology aspects were compared. Clinical samples (n ​= ​50) such as vesicle swab, buccal and throat swabs were collected for enterovirus detection. EV-RNA was detected by 5'NCR based RT-PCR and genotyping by VP1 gene amplification and cycle sequencing.

RESULTS

Of the cases of HFMD enrolled (n ​= ​50), highest (84%) were of children aged <5 years, presented either or both anathemas and exanthemas with prodromal symptoms (fever, irritability). Clinical presentations involved mainly oral ulcers on lips and tongue (48%). Oral erosions were either single or multiple in numbers. Exanthemas were seen on hand and palm, widely spread up to buttocks, legs, arms and trunk. Of these, six patients were found anemic. Complete blood count (CBC) indicated lymphocytosis and C-reactive protein (n ​= ​10) in children aged <5 years. EV-RNA was detected in 78% (39/50) of the clinical samples. VP1 gene based typing indicated the presence of CV-A16, CVA6 and EV-A71 types.

CONCLUSIONS

The study highlights association of EVs in HFMD cases in the reported region. CV-A16, CV-A6 and EV-A71 types were reported for the first time from Udhampur (J&K), Northern India. No differences were observed in the clinical profile of EV strains detected. Circulation of the strains warrant and alarm outbreaks. More focused studies on HFMD and monitoring of viral strains is mandatory.

Enterovirus 71 induces neural cell apoptosis and autophagy through promoting ACOX1 downregulation and ROS generation

Enterovirus 71 (EV71) infection causes hand, foot, and mouth disease (HFMD), and even fatal neurological complications. However, the mechanisms underlying EV71 neurological pathogeneses are largely unknown. This study reveals a distinct mechanism by which EV71 induces apoptosis and autophagy in neural cells. EV71 non-structure protein 3D (also known as RNA-dependent RNA polymerase, RdRp) interacts with the peroxisomal protein acyl-CoA oxidase 1 (ACOX1), and contributes to ACOX1 downregulation. Further studies demonstrate that EV71 reduces peroxisome numbers. Additionally, knockdown of ACOX1 or peroxin 19 (PEX19) induces apoptosis and autophagy in neural cells including human neuroblastoma (SK-N-SH) cells and human astrocytoma (U251) cells, and EV71 infection induces neural cell death through attenuating ACOX1 production. Moreover, EV71 infection and ACOX1 knockdown facilitate reactive oxygen species (ROS) production and attenuate the cytoprotective protein deglycase (DJ-1)/Nuclear factor erythroid 2-related factor 2 (NRF2)/Heme oxygenase 1 (HO-1) pathway (DJ-1/NRF2/HO-1), which collectively result in ROS accumulation in neural cells. In conclusion, EV71 downregulates ACOX1 protein expression, reduces peroxisome numbers, enhances ROS generation, and attenuates the DJ-1/NRF2/HO-1 pathway, thereby inducing apoptosis and autophagy in neural cells. These findings provide new insights into the mechanism underlying EV71-induced neural pathogenesis, and suggest potential treatments for EV71-associated diseases.

[Atypical hand, foot and mouth disease in adults: A note on 6 cases]

INTRODUCTION

Hand, foot and mouth disease (HFMD) is form of viral dermatosis well known among the pediatric population, in whom it has a typical presentation. However, it is less common in adults, with a more heterogeneous presentation, potentially making diagnosis extremely challenging for the clinician.

PATIENTS AND METHODS

This was a retrospective case series from 2013 to 2018 of HFMD in adults, with all cases being confirmed by cutaneous polymerase chain reaction (PCR). We studied the clinical, epidemiological and viral characteristics of each patient.

RESULTS

This series of 6 cases comprised 4 men and 2 women, with a mean age of 42.5 years. Five patients presented extended purpuric lesions, four had bullous lesions, and three showed cutaneous signs without any mucosal lesions. Extended lesions on the trunk were found in four patients. One patient presented rosette-shaped pustular lesions on the limbs, one had eczema-like lesions on the scalp, and one presented extended purpuric lesions on the soles.

DISCUSSION

These different cases of adult HFMD raise questions about differential diagnosis in relation to other acute cutaneous and mucous diseases. It is essential to be aware of these different types of presentation of the disease in order to determine the diagnosis and discuss preventive measures.

Non-clinical safety assessment of repeated intramuscular administration of an EV-A71 VLP vaccine in rabbits

A candidate hand, foot, and mouth disease vaccine comprising of human enterovirus A71 (EV-A71) virus-like particles (VLPs) was tested in rabbits to evaluate the potential local and systemic effects of this vaccine. The rabbits received more than double the full human dose and one additional dose according to the n + 1 recommended scheme. The three doses were given mixed with Alhydrogel adjuvant as intramuscular (IM) injections. Vaccinations were well-tolerated, with no indication of overt toxicity in any parameter observed. An EV-A71 specific immune response in the form of antibodies that specifically reacted with the virus capsid proteins VP1 and VP0, the complete VLP, and EV-A71 viruses of different subgenotypes to that of the vaccine could be demonstrated. A boosting effect in the form of higher EV-A71 specific antibody titers was observed after the subsequent doses, and these enhanced titers were shown to be statistically significant in one-way ANOVA analyses. Fortnightly intramuscular administration of EV-A71 VLP vaccine did not result in any test article-related changes in immunotoxicity as defined by increased serum IL-6, and in general IL-6 concentrations remained below the lower limit of quantitation for the majority of animals throughout the study. Although increased indicators of inflammation at the injection site were observed in animals sacrificed immediately after the last vaccination, these largely reversed at the end of the recovery phase. No findings suggestive of systemic or delayed toxicity were recorded in this independently conducted study. In conclusion, repeated IM administration of the EV-A71 VLP vaccine were locally and systemically well-tolerated in rabbits and immunogenic, supporting the clinical development of the vaccine.

Patterns of polymorphism and divergence in the VP1 gene of enterovirus 71 circulating in the Asia-Pacific region between 1994 and 2013

Enterovirus 71 has been implicated in several outbreaks of hand, foot and mouth disease in the Asia-Pacific region. The present study aimed to achieve comprehensive evolutionary dynamic aspects of EV71 during 1994-2013, based on phylogenetic analyses of the VP1 sequences. The results indicated that 4 genotypes, namely C4, C1, C2 and B4 are the predominant strains, especially in Southeast Asian countries. No common ancestor was shared in different countries. Fourteen sites of substitutions were detected in the VP1 gene sequences; including the most common sites related to neutralization at position V249I [47.1% (189/401)] and A289T [42.6% (171/401)]. However, the sites Q22H and Q22R associated with increased virulence were recognized only in 13.7% (55/401) and 18% (72/401), respectively. None of the above mutations seemed to become fixed because the ratio of Ka/Ks was greater than 1.0. Mutations K43E, A58T, S184T, and T240S could possibly change the spatial structure. Two mutations, G145E and T240S, could obviously affect the hydrophobicity of VP1 and thus alter the EV71 immunoreactivity. In conclusion, the VP1 gene of EV71 strains circulating in the Asia-Pacific region during 1994-2013, showed polymorphisms and divergence with very slow evolution rate, which may be one of the reasons for periodic outbreaks in this area.