A Narrative Review of Norovirus Gastroenteritis: More Global Attention Is Needed

Abstract

Introduction Acute gastroenteritis (diarrhea and vomiting) leads to 1.45 million deaths worldwide every year and is considered one of the greatest burdens of all infectious diseases, second only to respiratory infections. 1 Acute gastroenteritis can be caused by bacteria or viruses; the main viral pathogens of acute gastroenteritis are rotaviruses and Noroviruses (NoVs). Since the implementation of rotavirus vaccines in many countries, NoVs have replaced rotaviruses as the main etiologic agent of viral epidemic gastroenteritis. 2 They impose staggering economic costs and social burdens. 3 To date, there is no sufficient therapy or commercial vaccine for NoVs. 4 Viral Particle Structure and Function NoV was first discovered using electron microscopy (EM). It is a small, round (27-38 nm in diameter), non-enveloped, icosahedral virus belonging to the family Caliciviradae under the genus Norovirus. The NoV genome consists of a single positive-sense RNA which is approximately 7.5-7.7 kb and encodes three open reading frames (ORFs) 5 with the exception of the murine norovirus (MNV). MNV has a fourth alternative ORF. 6 The first ORF (ORF1) encodes a large nonstructural polyprotein which is post-translationally cleaved by a virus-encoded protease (Pro; NS6) into six or seven mature nonstructural proteins involved in viral replication 7 from the N to the C terminus including N-terminal protein (designated p48 for Norwalk virus; NS1-2), NTPase (p41; NS3), 3A-like protein (designated p22 for Norwalk virus; NS4), a viral genome-linked protein (VPg; NS5), viral protease (3Clpro; NS6), 8 and RNA-dependent RNA polymerase (RdRp; NS7). 9 The ORF2 and ORF3 encode the major capsid protein VP1 and the minor structure protein VP2, respectively. The icosahedral T3 recombinant NoV is formed by assembly of the 90 dimers of the VP1 capsid protein. VP1 is 1.8 kb in length and organized into two principal domains, the shell (S) and protrusion (P) domains. The S domain is highly conserved, which is related to the formation of the NoV's structure. The P domain can form virus-like particles, even with 20 aa missing in the N terminal, and still have no effect on the ability to function as a receptor. 10 The P domain is further subdivided into the P1 and P2 subdomains. The moderately flexible P1 sub-domain acts as a hinge to combine S and P2 sub-domains. The P2 sub-domain is located on the most distal surface and is highly variable. It http://ijtmgh.com

Distribution of group a Rotavirus circulating in Mashhad, Iran

“…In our study, Rotavirus was detected in 33 of 106 (31.3%) fecal samples which were collected from Dr. Sheikh and Akbar Pediatric Hospital of Mashhad, Iran. RT-PCR method was used to detect this viral infection in collected clinical stool specimens since this method was available, has acceptable sensitivity in detecting Rotaviruses ( 25 ) and can distinguish this infection from several other viral infections resulting in AGE including Noroviruses , enteric Adenoviruses serotypes 40 and 41, Human Parechoviruses, Picobirnaviruses, Astroviruses, and infrequently, Coronaviruses , and Toroviruses ( 26 , 27 ). In 2010, another study was done to investigate the prevalence of Rotavirus infection in Mashhad by Sadeghian et al Based on the results, the incidence of this viral infection among children suffering from AGE was 28.8% ( 28 ).…”

Environmental surveillance of norovirus and hepatitis A virus in raw oysters at seafood retails in Sinaloa, Mexico: detection of GII.P13 norovirus genotype

“…NoV is a non-enveloped virus member of the family Caliciviridae, which is characterized by a singlestranded positive-sense RNA genome ranging from 7.5 to 7.7 kb [3]. The NoV genome is organized in three open reading frames (ORF) in which ORF2 and ORF3 encodes the structural major and minor capsid proteins VP1 and VP2, respectively; whereas ORF1 encodes a nonstructural polyprotein that is processed by the viral protease NS6 resulting in six non-structural proteins including a RNAdependent RNA polymerase (RdRp) [3]. Of these, VP1 and RdRp genes have been extensively used to design molecular approaches to identify and assess genetic diversity of NoV [4].…”

Developments of an Emerging Infectious Agent: Norovirus

“…The outbreak of norovirus infection has been reported from different parts of world by several researchers [8][9][10]. The disease caused by norovirus is self-limiting but in several cases it is fatal resulting into death of infected person [11]. The commonest co-pathogen with norovirus infection is rotavius.…”