Parechovirus A Pathogenesis and the Enigma of Genotype A-3

Diagnosis, management, and outcomes of parechovirus infections in infants: an overview

Parechovirus A (PeV-A) infections have been detected with increasing frequency in US infants under 6 months of age, leading to a Centers for Disease Control and Prevention (CDC) health advisory in July 2022. Clinicians are advised to consider PeV-A laboratory testing of blood and cerebrospinal fluid when infants present with unexplained fever, sepsis-like illness, or neurological issues. Clinical laboratories are encouraged to offer in-house molecular testing for PeV-A to avoid diagnostic delays, unnecessary use of antibiotics, and prolonged hospitalization of infants presenting with sepsis-like illness. While data are evolving on potential neurodevelopmental sequelae after PeV-A infant central nervous system infections, most infected infants return to baseline health for age. This review examines the PeV-A literature with a focus on PeV-A3, including aspects of epidemiology, clinical presentations/management, laboratory diagnostics, genotyping, and post-infectious sequelae related to PeV-A infections in infants.

MYADM binds human parechovirus 1 and is essential for viral entry

Human parechoviruses (PeV-A) are increasingly being recognized as a cause of infection in neonates and young infants, leading to a spectrum of clinical manifestations ranging from mild gastrointestinal and respiratory illnesses to severe sepsis and meningitis. However, the host factors required for parechovirus entry and infection remain poorly characterized. Here, using genome-wide CRISPR/Cas9 loss-of-function screens, we identify myeloid-associated differentiation marker (MYADM) as a host factor essential for the entry of several human parechovirus genotypes including PeV-A1, PeV-A2 and PeV-A3. Genetic knockout of MYADM confers resistance to PeV-A infection in cell lines and in human gastrointestinal epithelial organoids. Using immunoprecipitation, we show that MYADM binds to PeV-A1 particles via its fourth extracellular loop, and we identify critical amino acid residues within the loop that mediate binding and infection. The demonstrated interaction between MYADM and PeV-A1, and its importance specifically for viral entry, suggest that MYADM is a virus receptor. Knockout of MYADM does not reduce PeV-A1 attachment to cells pointing to a role at the post-attachment stage. Our study suggests that MYADM is a multi-genotype receptor for human parechoviruses with potential as an antiviral target to combat disease associated with emerging parechoviruses.

Parechovirus infection in human brain organoids: host innate inflammatory response and not neuro-infectivity correlates to neurologic disease

Picornaviruses are a leading cause of central nervous system (CNS) infections. While genotypes such as parechovirus A3 (PeV-A3) and echovirus 11 (E11) can elicit severe neurological disease, the highly prevalent PeV-A1 is not associated with CNS disease. Here, we expand our current understanding of these differences in PeV-A CNS disease using human brain organoids and clinical isolates of the two PeV-A genotypes. Our data indicate that PeV-A1 and A3 specific differences in neurological disease are not due to infectivity of CNS cells as both viruses productively infect brain organoids with a similar cell tropism. Proteomic analysis shows that PeV-A infection significantly alters the host cell metabolism. The inflammatory response following PeV-A3 (and E11 infection) is significantly more potent than that upon PeV-A1 infection. Collectively, our findings align with clinical observations and suggest a role for neuroinflammation, rather than viral replication, in PeV-A3 (and E11) infection.

A Case Series of Infants 60 Days of Age or Younger With Human Parechovirus (PeV) Meningitis From a New York City Pediatric Emergency Department

Human parechovirus is a relatively lesser known virus that has recently spread across the United States, primarily affecting newborns and young infants. A particular strain of parechovirus, PeV-A3, has been found in the cerebrospinal fluid studies of many young patients in the spring and summer of 2022; however, short- and long-term neurologic effects of this virus are often not well known. We present a case series of 4 infants, 60 days of age or younger, found to have human parechovirus meningitis. Our retrospective study found that none of the 4 infants presented with any significant neurological findings, nor did they develop any specific neurologic signs or symptoms during their hospitalizations. Patients should continue to be monitored for long-term neurological and neurodevelopmental sequelae.

Assessment of the broad-spectrum host targeting antiviral efficacy of halofuginone hydrobromide in human airway, intestinal and brain organotypic models

Halofuginone hydrobromide has shown potent antiviral efficacy against a variety of viruses such as SARS-CoV-2, dengue, or chikungunya virus, and has, therefore, been hypothesized to have broad-spectrum antiviral activity. In this paper, we tested this broad-spectrum antiviral activity of Halofuginone hydrobomide against viruses from different families (Picornaviridae, Herpesviridae, Orthomyxoviridae, Coronaviridae, and Flaviviridae). To this end, we used relevant human models of the airway and intestinal epithelium and regionalized neural organoids. Halofuginone hydrobomide showed antiviral activity against SARS-CoV-2 in the airway epithelium with no toxicity at equivalent concentrations used in human clinical trials but not against any of the other tested viruses.

Parechovirus A Circulation and Testing Capacities in Europe, 2015-2021

Parechovirus infections usually affect neonates and young children; manifestations vary from asymptomatic to life-threatening. We describe laboratory capacity in Europe for assessing parechovirus circulation, seasonality, and epidemiology. We used retrospective anonymized data collected from parechovirus infection case-patients identified in Europe during January 2015-December 2021. Of 21 laboratories from 18 countries that participated in the study, 16 (76%) laboratories with parechovirus detection capacity reported 1,845 positive samples; 12/16 (75%) with typing capability successfully identified 517 samples. Parechovirus A3 was the most common type (n = 278), followed by A1 (153), A6 (50), A4 (13), A5 (22), and A14 (1). Clinical data from 1,269 participants highlighted correlation of types A3, A4, and A5 with severe disease in neonates. We observed a wide capacity in Europe to detect, type, and analyze parechovirus data. To enhance surveillance and response for PeV outbreaks, sharing typing protocols and data on parechovirus-positive cases should be encouraged.

Detection of parechovirus A in respiratory, gastrointestinal, and neurological clinical samples of pediatric patients from Panama (2014-2015)

Parechovirus A (PeV-A, Parechovirus, Picornaviridae) are human pathogens associated with mild to severe gastrointestinal and respiratory diseases in young children. While several studies have investigated the association of PeV-A with human disease, little is known about its epidemiology or detection in Latin America. Between the years 2014 and 2015, a total of 200 samples were collected from Panamanian pediatric patients aged < 16 years old exhibiting symptoms associated with respiratory (n = 64), gastrointestinal (n = 68), or neurological (n = 68) diseases. These samples were gathered from patients who had previously received negative diagnoses for the main respiratory viruses, rotavirus, and neurological viruses like herpes virus, enterovirus, and cytomegalovirus. The presence of PeV-A was analyzed by real time RT-PCR.Eight positive PeV-A infections (4.0%, 95% CI: 1.7 to 7.7) were detected: two in respiratory samples (3.0%, 95% CI: 0.3 to 10.8), five in gastrointestinal samples (7.3%, 95% CI: 2.4 to 16.3), and one in cerebrospinal fluid (1.5%, 95% CI: 1.4 to 7.9). The study provides evidence of PeV-A circulation in Panama and the data collectively, remarked on the importance of considering PeV-A in the Panamanian pediatric diagnostic landscape, especially when conventional testing for more common viruses yields negative results.

Update on nonpolio enterovirus and parechovirus infections in neonates and young infants

PURPOSE OF REVIEW

To review the epidemiology, clinical manifestations, and treatment strategies of nonpolio enterovirus and parechovirus (PeV) infections, and identify research gaps.

RECENT FINDINGS

There is currently no approved antiviral agent for enterovirus or PeV infections, although pocapavir may be provided on a compassionate basis. Elucidation of the structure and functional features of enterovirus and PeV may lead to novel therapeutic strategies, including vaccine development.

SUMMARY

Nonpolio human enterovirus and PeV are common childhood infections that are most severe among neonates and young infants. Although most infections are asymptomatic, severe disease resulting in substantial morbidity and mortality occurs worldwide and has been associated with local outbreaks. Long-term sequelae are not well understood but have been reported following neonatal infection of the central nervous system. The lack of antiviral treatment and effective vaccines highlight important knowledge gaps. Active surveillance ultimately may inform preventive strategies.

A Comparative Study of Acute Gastroenteritis Symptoms in Single- versus Multiple-Virus Infections

Many different enteric viruses can cause acute gastroenteritis in humans worldwide. While a single virus can indeed cause disease, multiple-virus infections are commonly reported. However, data regarding a comparison between single- and multiple-virus infections upon clinical manifestations of acute gastroenteritis are relatively limited. In this study, a total of 2383 fecal specimens were collected from children with acute gastroenteritis during June 2014-July 2017 in a pediatric clinic in Japan and tested for 11 viruses by multiplex RT-PCR. At least 1 virus was found in 1706 (71.6%) specimens and norovirus GII was the most frequent agent, followed by rotavirus A and other viruses. Multiple-virus infections were identified in 565 cases (33.1%). While major clinical symptoms were found to be significantly different in some single- vs. multiple-virus infections, the disease severity was statistically non-significant. Our study highlights the burden of multiple-virus infections for acute gastroenteritis and the clinical features of patients with multiple-virus infections.

Prevalence and genetic diversity of Parechovirus A in children with diarrhea in Beijing, China, 2017-2019

We analyzed the prevalence and genotypes of Parechovirus A (PeV-A) in children with diarrhea in Beijing, China, 2017-2019. A total of 1734 stool samples collected from children <5 years of age with diarrhea were tested for the presence of PeV-A. Viral RNA was detected by real-time RT-PCR, and then genotyped by nested RT-PCR. We detected PeV-A in 93 (5.4%, 93/1734) samples, of which 87 could be genotyped by amplification of either the complete or partial VP1 region or the VP3/VP1 junction region. The median age of PeV-A infected children was 10 months. Most PeV-A infections were observed between August and November, with a peak in September. Seven known genotypes of PeV-A1A, -A1B, -A3, -A4, -A6, -A8 and -A11 were detected and PeV-A1B was the most prevalent genotype. Coinfection with other diarrheal viruses was observed in 30.1% (28/93) of PeV-A positive samples. All strains of PeV-A1A, -A1B, -A4 and -A6 obtained in this study contained the arginine-glycine-aspartic (RGD) motif, while all strains of PeV-A3, -A8 and -A11 lacked it. This study revealed a high genetic diversity of PeV-A circulating in Beijing and PeV-A11 was reported for the first time in children with diarrhea in China.

Myeloid-associated differentiation marker is an essential host factor for human parechovirus PeV-A3 entry

Human parechovirus (PeV-A) is an RNA virus that belongs to the family Picornaviridae and it is currently classified into 19 genotypes. PeV-As usually cause mild illness in children and adults. Among the genotypes, PeV-A3 can cause severe diseases in neonates and young infants, resulting in neurological sequelae and death. In this study, we identify the human myeloid-associated differentiation marker (MYADM) as an essential host factor for the entry of six PeV-As (PeV-A1 to PeV-A6), including PeV-A3. The infection of six PeV-As (PeV-A1 to PeV-A6) to human cells is abolished by knocking out the expression of MYADM. Hamster BHK-21 cells are resistant to PeV-A infection, but the expression of human MYADM in BHK-21 confers PeV-A infection and viral production. Furthermore, VP0 capsid protein of PeV-A3 interacts with one extracellular domain of human MYADM on the cell membrane of BHK-21. The identification of MYADM as an essential entry factor for PeV-As infection is expected to advance our understanding of the pathogenesis of PeV-As.

Positive-strand RNA viruses-a Keystone Symposia report

Positive-strand RNA viruses have been the cause of several recent outbreaks and epidemics, including the Zika virus epidemic in 2015, the SARS outbreak in 2003, and the ongoing SARS-CoV-2 pandemic. On June 18-22, 2022, researchers focusing on positive-strand RNA viruses met for the Keystone Symposium "Positive-Strand RNA Viruses" to share the latest research in molecular and cell biology, virology, immunology, vaccinology, and antiviral drug development. This report presents concise summaries of the scientific discussions at the symposium.

The fecal and oropharyngeal eukaryotic viromes of healthy infants during the first year of life are personal

Using a metagenomic sequencing approach, we described and compared the diversity and dynamics of the oropharyngeal and fecal eukaryotic virome of nine asymptomatic children in a semi-rural community setting located in the State of Morelos, Mexico. Ninety oropharyngeal swabs and 97 fecal samples were collected starting 2 weeks after birth and monthly thereafter until 12 months of age. In both niches, more than 95% of the total sequence reads were represented by viruses that replicate either in humans or in plants. Regarding human viruses, three families were most abundant and frequent in the oropharynx: Herpesviridae, Picornaviridae, and Reoviridae; in fecal samples, four virus families predominated: Caliciviridae, Picornaviridae, Reoviridae, and Anelloviridae. Both niches showed a high abundance of plant viruses of the family Virgaviridae. Differences in the frequency and abundance of sequence reads and diversity of virus species were observed in both niches and throughout the year of study, with some viruses already present in the first months of life. Our results suggest that the children's virome is dynamic and likely shaped by the environment, feeding, and age. Moreover, composition analysis suggests that the virome composition is mostly individual. Whether this constant exposition to different viruses has a long-term impact on children's health or development remains to be studied.

Identification and genome characterization of novel parechovirus sequences from Hipposideros armiger in China

Background

Bats were identified as a natural reservoir of emerging and re-emerging infectious pathogens threatening human health and life.

Methods

This study collected 21 fecal samples of Hipposideros armiger in Mengla County of Xishuangbanna Prefecture Yunnan Province to combine one pool for viral metagenomic sequencing.

Results

Two nearly complete genomes of parechoviruses, BPeV11 and BPeV20, were sequenced. Genome analysis revealed that BPeV11 and BPeV20 follow a 3-3-4 genome layout: 5′ UTR-VP0-VP3-VP1-2A-2B-2C-3A-3B-3C-3D-3′ UTR. The prevalence of BPev11 and BPev20 by Nested-PCR showed that 1 of 21 fecal samples was positive. Based on amino acid identity comparison and phylogenetic analysis of P1, 2C, and 3D, BPeV11 and BPeV20 were closely related to but distinct from FPeVs.

Conclusion

It was probably proposed to be a novel species in the genus Parechovirus of the family Picornaviridae. The isolation of BPev11 and BPev20 from H. armiger in China is the first complete genome of parechovirus isolations from bat feces of the genus Hipposideros.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01806-1.

The N-terminal region (VP4) of the foot-and-mouth disease capsid precursor (P1-2A) is not required during its synthesis to allow subsequent processing by the 3C protease

The capsid precursor (P1-2A) of foot-and-mouth disease virus is processed by the 3C protease (3Cpro) to VP0, VP3 and VP1 plus 2A. During capsid assembly, the VP0 is cleaved to VP4 plus VP2. Single amino acid changes in a conserved motif (YCPRP) near the C-terminus of VP1 can block processing of the capsid precursor by the 3Cpro, although the cleavage sites are located hundreds of amino acids distant from this motif, presumably due to misfolding. In contrast, we show here that the absence of the VP4 sequence during the synthesis of the capsid precursor does not affect its subsequent processing. Cleavage of this truncated precursor by 3Cpro at the VP3/VP1 and VP2/VP3 junctions occurred efficiently. Thus, in contrast to the presence of the YCPRP motif in VP1, there are no critical motifs near the N-terminus of the precursor, within VP4, required for correct cleavage by 3Cpro.

Characterization of Pathogenesis and Inflammatory Responses to Experimental Parechovirus Encephalitis

Human parechovirus type 3 (PeV-A3) infection has been recognized as an emerging etiologic factor causing severe nerve disease or sepsis in infants and young children. But the neuropathogenic mechanisms of PeV-A3 remain unknown. To understand the pathogenesis of PeV-A3 infection in the neuronal system, PeV-A3-mediated cytopathic effects were analyzed in human glioblastoma cells and neuroblastoma cells. PeV-A3 induced interferons and inflammatory cytokine expression in these neuronal cells. The pronounced cytopathic effects accompanied with activation of death signaling pathways of apoptosis, autophagy, and pyroptosis were detected. A new experimental disease model of parechovirus encephalitis was established. In the disease model, intracranial inoculation with PeV-A3 in C57BL/6 neonatal mice showed body weight loss, hindlimb paralysis, and approximately 20% mortality. PeV-A3 infection in the hippocampus and cortex regions of the neonatal mouse brain was revealed. Mechanistic assay supported the in vitro results, indicating detection of PeV-A3 replication, inflammatory cytokine expression, and death signaling transduction in mouse brain tissues. These in vitro and in vivo studies revealed that the activation of death signaling and inflammation responses is involved in PeV-A3-mediated neurological disorders. The present results might account for some of the PeV-A3-associated clinical manifestations.

Parechovirus A Infection of the Intestinal Epithelium: Differences Between Genotypes A1 and A3

Human parechovirus (PeV-A), one of the species within the Picornaviridae family, is known to cause disease in humans. The most commonly detected genotypes are PeV-A1, associated with mild gastrointestinal disease in young children, and PeV-A3, linked to severe disease with neurological symptoms in neonates. As PeV-A are detectable in stool and nasopharyngeal samples, entry is speculated to occur via the respiratory and gastro-intestinal routes. In this study, we characterized PeV-A1 and PeV-A3 replication and tropism in the intestinal epithelium using a primary 2D model based on human fetal enteroids. This model was permissive to infection with lab-adapted strains and clinical isolates of PeV-A1, but for PeV-A3, infection could only be established with clinical isolates. Replication was highest with infection established from the basolateral side with apical shedding for both genotypes. Compared to PeV-A1, replication kinetics of PeV-A3 were slower. Interestingly, there was a difference in cell tropism with PeV-A1 infecting both Paneth cells and enterocytes, while PeV-A3 infected mainly goblet cells. This difference in cell tropism may explain the difference in replication kinetics and associated disease in humans.

Parent-administered Neurodevelopmental Follow up in Children After Picornavirus CNS Infections

BACKGROUND

Data on the neurodevelopment of children who experienced central nervous system (CNS) infections with enteroviruses (EV) or parechoviruses (hPeV) is scarce and mostly limited to follow up of short-term outcomes.

METHODS

Parents of children who presented between 2014 and 2019, underwent a lumbar puncture and whose cerebrospinal fluid was polymerase chain reaction positive for EV or hPeV, were asked to complete a care-giver-administered neurodevelopmental assessment tool (The Ages and Stages Instrument [ASQ3]). Clinical data of the infective episode were collected from patient notes.

RESULTS

Of 101 children, 43 (10 hPeV+, 33 EV+) submitted ASQ3 results. Median age at assessment was 38.9 months (interquartile range, 15.4-54.8), the follow-up interval 3 years (median 37 months; interquartile range, 13.9-53.1). Age, inflammatory markers, and cerebrospinal fluid pleocytosis during the infective event were not associated with ASQ3 scores. In 23 children (17 EV+, 6 hPeV+), no neurodevelopmental concerns were reported. Two more had preexisting developmental delay and were excluded. Of the remaining, 18/41 (43.9%) reported ASQ3 scores indicating need for monitoring or professional review in at least 1 category, not differing by pathogen (EV 14/31, 45.2%; hPeV 4/10, 40%; P = 0.71). Seven children will require formal review, scoring ≥2 SD below the mean in at least 1 category (6/31 EV+, 1/10 hPeV+, P = 0.7), 3 scored ≥2 SD below the mean in more than 1 area.

CONCLUSIONS

Parent-administered developmental assessment of children with a history of early picornavirus infection of the CNS identified a subgroup that requires formal neurodevelopmental review. Wider application of community-based developmental screening will complement our understanding of the impact of CNS infections in early childhood.

Parechovirus and enteroviruses among young infants with sepsis in Iran

Background and Objectives

Human parechoviruses (HPeV) and Human enteroviruses (EV) frequently cause a sepsis-like illness in young infants (younger than three months). Therefore, this study was conducted to determine the frequency of HPeV and EV among the young infants with clinical signs and symptoms of sepsis in Ahvaz city, Iran.

Materials and Methods

The blood specimens were collected from 100 (younger than 90 days hospitalized infants) including 54 (56.25%) males and 46 (43.75%) females with clinical signs and symptoms of sepsis-like disease. The RNA was extracted and tested for detection of VP1 region of HPeV and 5 UTR (Untranslated Region) of EV by RT-PCR. The sequences of positive of HPeV were further analyzed to determine HPeV genotyping.

Results

5/100 (5%) of patients including 2/46 (2%) females and 3/54 (3%) males tested positive for HPeV (P=0.85). The analysis of 5 positive VP1 region of HPeV revealed the genotype 1. The analysis of sequencing and phylogenetic tree revealed that the isolated HPeVs were genotype 1. While 38/100 (38%) specimens including 16 (16%) females and 22 (22%) males were tested positive for EV (P=0.68).

Conclusion

The frequency of HPeV genotype 1 was 5% among the young infants with sepsis. While frequency of EV was 38% among the young infants with sepsis. This study showed HPeV genotype 1 and EV are dominant in this region.

A comparative analysis of parechovirus protein structures with other picornaviruses

Parechoviruses belong to the genus Parechovirus within the family Picornaviridae and are non-enveloped icosahedral viruses with a single-stranded RNA genome. Parechoviruses include human and animal pathogens classified into six species. Those that infect humans belong to the Parechovirus A species and can cause infections ranging from mild gastrointestinal or respiratory illness to severe neonatal sepsis. There are no approved antivirals available to treat parechovirus (nor any other picornavirus) infections. In this parechovirus review, we focus on the cleaved protein products resulting from the polyprotein processing after translation comparing and contrasting their known or predicted structures and functions to those of other picornaviruses. The review also includes our original analysis from sequence and structure prediction. This review highlights significant structural differences between parechoviral and other picornaviral proteins, suggesting that parechovirus drug development should specifically be directed to parechoviral targets.

Severity of parechovirus infections in infants under 3 months of age and comparison with enterovirus infections: A French retrospective study

While enteroviruses (EV) are a well-recognized cause of aseptic meningitis in children, human parechoviruses (HPeV), especially genotype 3, have been increasingly reported as a frequent cause of sepsis-like illness and meningitis among young infants. The aim of this study was to describe the epidemiological, clinical, and laboratory characteristics of HPeV infections in infants and to compare them with those of well-known EV infections. This monocentric retrospective study was carried out at the pediatric unit of Nantes University Hospital from January 2015 to August 2018. All patients under 18 years of age with diagnosis codes referring to fever, for whom viral infection was suspected and cerebrospinal fluid (CSF) specimens were collected, were included. All CSF specimens were screened by duplex real-time polymerase chain reaction (PCR) assay that allows for the simultaneous detection of EV and HPeV in clinical samples. During the study period, 1373 CSF specimens from patients under 18 were included. A total of 312 CSF samples were positive for HPeV (n=34) or EV (n=278). Among the 34 HPeV-positive patients, 97% (33/34) were under 3 months of age, whereas the rate was 54% (149/278) for EV-positive patients (P<0.001); thus, patients under 3 months of age were defined as the study population for the rest of this work. A review of the medical records was carried out for the positive cases. In this population, the HPeV detection rate was 5.6% versus 25.3% (P<0.001) for EV. All but one of the HPeV samples available for genotyping were HPeV-3. No seasonality was observed for HPeV infections. Length of hospital stay tended to be longer for children infected with HPeV compared with those infected by EV (3 days vs. 2 days, P=0.05). Clinicians reported more severe illness presentations among HPeV-infected infants, with more frequent administration of fluid bolus (P<0.02). Regarding laboratory characteristics, a significant lack of cellular reaction in the CSF (P=0.004) as well as lower C-reactive protein (CRP) levels (P=0.006) and neutrophil counts (P<0.001) were noted for HPeV infections compared with EV infections. Our results confirm the early onset of HPeV infections (more than 95% of patients aged under 3 months). The clinical presentation and laboratory characteristics of the two infections was similar. However, some higher clinical severity criteria and a lack of CSF pleocytosis were regularly observed in patients with HPeV infections. Considering the significant proportion (5.6%; 95% CI, 3.7-7.5) of all CSF samples in our series, HPeV detection should be systematically included in the microbiological diagnosis of febrile children under 3 months of age.

Genetic diversity of Parechovirus A in infants and children with acute gastroenteritis in Japan during 2016-2018

Parechovirus A (PeV-A), previously known as human parechovirus, is a common pathogen in children that can cause respiratory and gastrointestinal diseases as well as severe neurological disease. Take advantage of our previous findings on the genetic diversity of PeV-A circulating in Japanese children with acute gastroenteritis (AGE), this study was conducted to investigate the genetic diversity of PeV-A isolated from children with AGE in Japan as well as their clinical symptoms. Of 1070 stool samples collected from Japanese infants and children with AGE during the 2-year period from July 2016 to June 2018, 76 were positive for PeV-A by multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) and were subjected to genotyping based on viral protein 1 (VP1) sequences. Five different PeV-A genotypes including PeV-A1B, -A2, -A3, -A4, and -A6 were detected with predominant of PeV-A1 clade B genotype. This study revealed a high genetic diversity of PeV-A circulating in Japanese infants and children with AGE and the PeV-A2, a rare genotype, was detected for the first time in Japan in patients with AGE. The clinical symptoms observed in these patients included diarrhea, vomiting, fever, cough, rhinorrhea, and dehydration.

Human parechovirus are emerging pathogens with broad spectrum of clinical syndromes in adults

Parechoviruses are emerging pathogens of humans often affecting the pediatric age group, with a growing line of evidence implicating them as agents of a broad spectrum of clinical syndromes in adults. However, because many clinicians are not familiar with the manifestation of the infections, they are not included in the list of diagnostic pathogens. Furthermore, due to the indistinguishable feature of the infection compared with other common pathogens, a large number of cases are likely to go unchecked. Some may develop asymptomatic infection and recover without overt clinical disease. In this manuscript, we reviewed available literature on parechovirus infection in adult and summarized information relating to epidemiology, clinical manifestation, laboratory diagnosis, and therapeutics. The information provided should help in early case detection and support an evidence-based clinical decision.