Enterovirus A71 Induces Neurological Diseases and Dynamic Variants in Oral Infection of Human SCARB2-Transgenic Weaned Mice

MIRA/PfAgo-Mediated Biosensor for Multiplex Human Enteroviruses Virus Typing Detection on HFMD

Hand, foot, and mouth disease (HFMD), caused by enteroviruses, mostly including EV71, CVA6, CVA10, and CVA16, is an acute infectious disease commonly found in children. Due to no approved antiviral therapies and available vaccines, except for EV71, developing accurate diagnostic methods of HFMD is essential for controlling its spread and mitigating its impact on public health. Here, we create a MIRA-HEV-PAND multiple nucleic acid typing method that utilizes PfAgo to identify enterovirus type A pathogens (EV71, CVA6, CVA10, and CVA16) and universal type EVU. The MDC (minimum detection concentration) level of MIRA-HEV-PAND is within the range of 1.66 aM (1.0 copy/μL), which was matched to that of qPCR assays and even more sensitive up to 10%. Importantly, the MIRA-HEV-PAND method exhibits higher sensitivity and less time-consuming efficiency compared to the approach that combines PCR amplification instead of MIRA amplification. Meanwhile, though the quintuple and single-tube multiple MIRA-HEV-PAND detection system can be used for one viral target or multiple viral target detection, the single-tube detection system detects more efficiently and rapidly than the quintuple-tube multiple detection system. Moreover, the diagnostic results obtained by evaluating clinical samples using MIRA-HEV-PAND show a complete consistency of 100% with qPCR assays. The MIRA-HEV-PAND method can screen a wider range of target regions using low-cost guide DNA without being limited to PAM sequences, compared to the MARPLES based on the CRISPR-Cas12a. The utilization of this correlation can be beneficial for the application of molecular testing for clinical diagnoses and the study of human enteroviruses A infection and virus typing on an epidemiological scale.

Overview of the Trending Enteric Viruses and Their Pathogenesis in Intestinal Epithelial Cell Infection

Enteric virus infection is a major public health issue worldwide. Enteric viruses have become epidemic infectious diseases in several countries. Enteric viruses primarily infect the gastrointestinal tract and complete their life cycle in intestinal epithelial cells. These viruses are transmitted via the fecal-oral route through contaminated food, water, or person to person and cause similar common symptoms, including vomiting, abdominal pain, and diarrhea. Diarrheal disease is the third leading cause of death in children under five years of age, accounting for approximately 1.7 billion cases and 443,832 deaths annually in this age group. Additionally, some enteric viruses can invade other tissues, leading to severe conditions and even death. The pathogenic mechanisms of enteric viruses are also unclear. In this review, we organized the research on trending enteric virus infections, including rotavirus, norovirus, adenovirus, Enterovirus-A71, Coxsackievirus A6, and Echovirus 11. Furthermore, we discuss the gastrointestinal effects and pathogenic mechanisms of SARS-CoV-2 in intestinal epithelial cells, given the gastrointestinal symptoms observed during the COVID-19 pandemic. We conducted a literature review on their pathogenic mechanisms, which serves as a guide for formulating future treatment strategies for enteric virus infections.

Novel intertypic recombination of Echovirus 11 in the Enterovirus species B

Enteroviruses (EVs), single-stranded, positive-sense RNA viruses, can be classified into four species (A-D), which have previously been linked to a diverse range of disease manifestations and infections affecting the central nervous system. In the Enterovirus species B (EV-B), Echovirus type 11 (E11) has been observed to occasionally circulate in Taiwan, which was responsible for an epidemic of enterovirus infections in 2018. Here, 48 clinical specimens isolated in 2003, 2004, 2009, and 2018 were collected for the high-throughput sequencing. Notably, we identified 2018 Taiwanese strains having potential recombinations in the 3D gene, as well as one 2003 strain having a double recombination with E6 and Coxsackievirus B5 in the P2 and P3 regions, respectively. Additionally, one amino acid signature mutated from the Histidine (H) in throat swab specimens to the Tyrosine (Y) in cerebral spinal fluid specimens was detected at position 1496 (or 57) of the genomic coordinate (or 3A gene) to further demonstrate intra-host evolution in different organs. In conclusion, this study identifies potential intertypic recombination events and an intra-host signature mutation in E11 strains, isolated during a 2018 neurological disease outbreak in Taiwan, contributing to our understanding of its evolution and pathogenesis.

Pathogenesis of enterovirus infection in central nervous system

Enteroviruses (EVs) are classified into 15 species according to their sequence diversity. They include four human EV (A, B, C, and D) and three rhinoviruses (A, B, and C), and cause diseases in millions of people worldwide. Generally, individuals with enteroviral infections have mild clinical symptoms, including respiratory illness, vomiting, diarrhea, dizziness, and fever. More importantly, some members of the human EV family are neurotropic pathogens that may cause a wide range of clinical diseases, such as aseptic meningitis and encephalitis. Previously, the EV that caused the most severe neurotropic symptoms was poliovirus (PV), a member of the EV C group. Poliovirus has been eliminated in most countries through a global vaccination campaign. Non-PV EVs infect the central nervous system (CNS) and are the major EVs causing neurological diseases. These human non-PV EVs include EV A (e.g., EV-A71, CVA6, and CVA16), B (e.g., CVA9 and CVB3, CVB5, echovirus 11 [E11], E30, and E7), C (e.g., CVA24), and D (e.g., EV-D68). Here, we review the relationship between EV infection and CNS diseases and advance in the use of cellular receptors and host immune responses during viral infection.

Investigating the mechanism of Echovirus 30 cell invasion

Viruses invade susceptible cells through a complex mechanism before injecting their genetic material into them. This causes direct damage to the host cell, as well as resulting in disease in the corresponding system. Echovirus type 30 (E30) is a member of the Enterovirus B group and has recently been reported to cause central nervous system (CNS) disorders, leading to viral encephalitis and viral meningitis in children. In this review, we aim to help in improving the understanding of the mechanisms of CNS diseases caused by E30 for the subsequent development of relevant drugs and vaccines.

Variant enterovirus A71 found in immune-suppressed patient binds to heparan sulfate and exhibits neurotropism in B-cell-depleted mice

Enterovirus A71 (EV-A71) causes hand, foot, and mouth disease outbreaks with neurological complications and deaths. We previously isolated an EV-A71 variant in the stool, cerebrospinal fluid, and blood of an immunocompromised patient who had a leucine-to-arginine substitution on the VP1 capsid protein, resulting in increased heparin sulfate binding. We show here that this mutation increases the virus's pathogenicity in orally infected mice with depleted B cells, which mimics the patient's immune status, and increases susceptibility to neutralizing antibodies. However, a double mutant with even greater heparin sulfate affinity is not pathogenic, suggesting that increased heparin sulfate affinity may trap virions in peripheral tissues and reduce neurovirulence. This research sheds light on the increased pathogenicity of variant with heparin sulfate (HS)-binding ability in individuals with decreased B cell immunity.

The internal ribosome entry site determines the neurotropic potential of enterovirus A71

The mechanisms underlying tissue-specific replication of enteroviruses are currently unclear. Although enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are both common pathogens that cause hand-foot-mouth disease, they display quite different neurotropic properties. Herein, we characterized the role of the internal ribosomal entry site (IRES) in determining neurovirulence using an oral inoculation model of EV-A71. The receptor transgenic (hSCARB2-Tg) mice developed neurological symptoms after being infected with a mouse-adapted EV-A71 strain (MP4) via different administrative routes. Intragastric administration of the MP4 strain caused pathological changes such as neuronal loss and neuropil vacuolation, whereas replacing EV-A71 IRES with CV-A16 abolished the neuropathological phenotypes. The attenuated neurotropic potential of IRES-swapped EV-A71 was observed even in mice that received intraperitoneal and intracerebral inoculations. Fewer chimeric MP4 viral RNAs and proteins were detected in the mouse tissues, regardless of the inoculation route. Tissue-specific replication can be reflected in cell-based characterization. While chimeric MP4 virus replicated poorly in human intestinal C2BBe1 and neuroblastoma SH-SY5Y cells, its replication in susceptible rhabdomyosarcoma cells was not affected. Overall, our results demonstrated that the IRES determined the neurotropic potential of EV-A71 and CV-A16, emphasizing the importance of the IRES in tissue tropism, along with the host receptors.