Parechovirus

Parechovirus is a genus of viruses in the family Picornaviridae. These viruses are small, non-enveloped, and have a single-stranded RNA genome. Parechoviruses are known to infect humans and other mammals, causing a range of diseases from mild gastrointestinal and respiratory illnesses to more severe conditions such as meningitis and encephalitis.

Taxonomy

The genus Parechovirus is part of the family Picornaviridae, which also includes other genera such as Enterovirus and Rhinovirus. The genus is divided into several species, with Human parechovirus (HPeV) being the most well-known due to its impact on human health.

Structure

Parechoviruses are small, approximately 30 nm in diameter, and have an icosahedral capsid. The capsid is composed of 60 copies each of four structural proteins: VP1, VP2, VP3, and VP4. Unlike many other picornaviruses, parechoviruses lack the VP4 protein, which is replaced by an extended N-terminus of VP1.

Genome

The genome of parechoviruses is a positive-sense single-stranded RNA, approximately 7,300 nucleotides in length. It contains a single open reading frame (ORF) that encodes a polyprotein, which is subsequently cleaved into structural and non-structural proteins. The genome is flanked by untranslated regions (UTRs) at both the 5' and 3' ends, which play roles in replication and translation.

Pathogenesis

Human parechoviruses are primarily transmitted via the fecal-oral route, but respiratory transmission is also possible. Infections are most common in infants and young children. While many infections are asymptomatic or result in mild illness, HPeV can cause severe disease, particularly in neonates, leading to sepsis, meningitis, and encephalitis.

Clinical Manifestations

- Gastrointestinal symptoms: Diarrhea, vomiting, and abdominal pain. - Respiratory symptoms: Cough, sore throat, and runny nose. - Neurological symptoms: Fever, irritability, seizures, and altered mental status in severe cases.

Diagnosis

Diagnosis of parechovirus infection is typically made by detecting viral RNA in clinical specimens using reverse transcription polymerase chain reaction (RT-PCR). Specimens commonly tested include stool, cerebrospinal fluid (CSF), and respiratory secretions.

Treatment

There is no specific antiviral treatment for parechovirus infections. Management is primarily supportive, focusing on maintaining hydration and treating symptoms. Severe cases, particularly those involving the central nervous system, may require hospitalization and intensive care.

Prevention

Preventive measures include good hygiene practices such as handwashing and avoiding close contact with infected individuals. There are currently no vaccines available for parechovirus.

Also see

• Picornaviridae
• Enterovirus
• Rhinovirus
• Meningitis
• Encephalitis

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