Background & Aim: Human parechovirus is a genus of PICORNAVIRUSES which includes a number of important viruses of clinical significance. Recent sequence analysis suggests that human parechovirus type 1 (HPEV-1) is distinct from other PICORNAVIRUSES and lacks the motives believed to be involved in the protease function of 2A. The aim of this study was to analyze proteolytic activity of 3C protein in human parechovirus type 1.Materials and Method: The region of HPEV-1 cDNA that was coded for 3C protein was inserted into plasmid pUBS by Ligase enzyme and pFG3 recombinant plasmid was prepared. After transformation and replication of this plasmid in E.coli MC 10.22, DNA was isolated by phenol extraction and then expressed in prokaryotic (E.coli BL-21) and in vitro systems under T7 promoter. The results were detected by SDS-PAGE and analyzed. Results: The products of expression of recombinant plasmid (not included 3C gene) in both prokaryotic and in vitro systems were analyzed. Just one large band (90 KD) was observed, but with plasmid including 3C gene, several small bands were detected. These results indicated proteolytic activity of 3C protein. After addition of anti protease to the products of plasmid with 3C gene the result was the same as the plasmid without 3C gene.Conclusion: The results showed that HPEV-1 has a processing strategy different from other members of PICORNAVIRUSES, and 3C protein seems to be the only virus encoded protease that can catalyze cleavages of all sites in the parechoviruses primary polyprotein.

Parechoviruses form one of the nine genera in the picornaviridae family, and include two human pathogens: Human parechovirus type 1 and 2 (Hpev 1 and Hpev2). The genome of PICORNAVIRUSES encodes a single polyprotein, which undergoes a cleavage cascade performed by virus encoded proteases to give the final virus proteins. The primary cleavage occurs by 2A protein and this step is critical for viral life cycle.Recent sequence analysis suggests that Hpev1. is distinct from other picomaviruses and lacks the motifs believed to be involved in the protease function of 2A. The aim of this study was to analyze proteolytic activity of 2A protein in Hpev 1. For this purpose we made several recombinant plasmids contain 2A region of parechovirus typel genome and expressed in prokaryotic and in vitro systems under T7 promoter.Analyzing the expression products by SDS-PAGE revealed just a large single band (90 KDa), the same size as primary translation product. Whereas with plasmids include 3C gene several small bands were observed, indicating that processing had occurred. In conclusion: the results of this work .show that Human parechovirus type 1 has a processing strategy different from the other members of PICORNAVIRUSES and in this virus, as in hepatovirus, 2A protein does not have a protease function.

Backgrounds and Objections: Human parechovirus is a genus of picornaviridae. All of PICORNAVIRUSES have a 3C protease which has a key role in virus protein processing and replication. The aim of this study was to analyse polyprotein processing in human Parechovirus typel by cloning and expression of 3C gene. Materials and Methods: After preparation of cDNA from human parechovirus type 1 (HPEV-l) RNA genome the region of cDNA that was encoded for 3C protein was inserted into plasmid pUBS by Ligase enzyme and recombinant plasmid was prepared. After transformation and replication of this plasmid in E.coli MC 10.22, DNA was isolated by phenol extraction and then expressed in prokaryotic (E.coli BL-21) and In vitro systems under T7 promoter. The results were detected by SDS-PAGE and analyzed. Results: The products of expression of recombinant plasmids (with out 3C gene) in both prokaryotic and in vitro systems were analyzed. Just one large band same size as primary translation product was observed, but with plasmid including 3C gene, several small bands were detected. These results indicate that human Parechovirus typel polyprotein processing occurs by 3C protease. 3C protease was checked by anti protease.Conclusion: Our results showed that HPEV-1has a processing strategy different from other members of PICORNAVIRUSES, and 3C protein seems to be the only virus encoded protease that can catalyze cleavages of all sites in the Parechovirus type] primary polyprotein.

Background: Human parechoviruses (HPeV) are rapidly evolving PICORNAVIRUSES that may cause sepsis-/meningitis-like illness in infants. The present study aimed to evaluate the occurrence and quantity of human parechovirus in 160 cerebrospinal fluid samples of children under 5 years old with meningitis and meningoencephalitis hospitalized at Karaj Imam Ali Hospital. Materials and methods: 160 CSF samples were collected during September 2019 to October 2020 in karaj province, Iran from hospitalized children with meningitis and meningoencephalitis. They were subject to detect HPeV using consensus primers targeted to their 5′, UTR s. Results: Out of 160 samples of cerebrospinal fluid, two samples (1. 25%) were positive for human parechovirus. The maximum viral load of HPeV was 5. 6 × 106 copies / ml in December and in a 3. 5 years old female patient and the minimum viral load was 3. 2 × 104 copies / ml in February in a 4. 5 years old female patient. Conclusion: In this study for the first time, the presence of human parecovirus in the cerebrospinal fluid samples of children under 5 years of age with meningitis and meningoencephalitis hospitalized in Imam Ali Karaj Hospital reported. Two samples out of 160 cerebrospinal fluid samples were positive. It indicates the relationship between human parechovirus and neurological disorders.