key: cord-286711-nr6vnl9h
authors: nan
title: Other viruses causing gastroenteritis
date: 2003-12-31
journal: Perspectives in Medical Virology
DOI: 10.1016/s0168-7069(03)09037-2
sha: 
doc_id: 286711
cord_uid: nr6vnl9h

Publisher Summary Besides the viruses producing the majority of human viral gastroenteritis, other viruses infect more rarely but are sometimes able to cause epidemics. In particular, they cause chronic infection in the immunocompromised. Some of these viruses discussed in this chapter are toroviruses, picobirnaviruses, enteroviruses, human immunodeficiency virus (HIV), herpesviruses, and coronaviruses. Toroviruses make up a genus of the Coronaviridae family. They are a well-described cause of diarrhea in calves and horses but may also infect sheep, goats, and pigs. Picobirnaviruses are related to members of the Birnaviridae family. They are found in the feces of HIV-infected patients with diarrhea more frequently than in HIV-infected patients without diarrhea, but a virus-specific immune response was not measurable. The genus Enterovirus is of the Picornaviridae family. All enteroviruses infect man via the gastrointestinal tract where they have their first site of replication, probably in lymphoid tissues of the pharynx and gut. HIV, the causative agent of the acquired immunodeficiency syndrome (AIDS), is a member of the Lentivirus genus of the Retroviridae family. Cytomegalovirus (CMV) and herpes simplex viruses, members of the Herpesviridae family, are found as the cause of colitis and esophagitis, mainly in HIV-infected patients. Coronavirus is another genus of the Coronaviridae family. Coronaviruses infect the respiratory and gastrointestinal tracts. They are a recognized cause of the common cold in man.

Besides the viruses producing the majority of human viral gastroenteritis (Sections II-V), other viruses infect more rarely, but are sometimes able to cause epidemics. In particular, they cause chronic infection in the immunocompromised.

Torovimses comprise a genus of the Coronaviridae family (Enjuanes et al., 2000) . They are enveloped and possess a genome of single stranded RNA of positive polarity which is approximately 20-25kb in size. The RNA is surrounded by nucleoprotein (N) in helical symmetry. The nucleocapsid has a toroid shape (inspiring the name from lat. torus = convex moulding of a column) and is enclosed in an envelope consisting of membrane protein (M) and a lipid bilayer. Inserted in the envelope are the surface proteins S (for spike) and HE (for haemagglutinin-esterase). The HE protein has sequence similarities with corresponding proteins of coronaviruses and influenza C viruses. Toroviruses may have acquired this gene by a recombination event in the past. Replication is special in that mRNA is synthesized from 'core promoters' of a negative stranded RNA template and not by fusion of a common leader sequence with subgenomic transcripts as in the coronaviruses (Snijder and Horzinek, 1995) .

Toroviruses are a well-described cause of diarrhoea in calves (BoTV; Breda V) and horses (EqTV, Berne virus) but may also infect sheep, goats and pigs. Humans seem to become infected by a closely related, but distinct virus (HuTV) (Koopmans and Horzinek, 1994; Enjuanes et al., 2000) . In cases of human diarrhoea toroviruses have been diagnosed by electron microscopy and EIA (Koopmans et al., 1993) . In a recent survey in Canada of 1365 faeces from children with diarrhoea, rotavirus was found in 32%, adenovirus in 4%, torovirus in 3%, Norwalk like viruses in 2%, and astroviruses and Sapporo-like viruses each in tess than 1% (Waters et al., 2000) . This suggested that toroviruses are not a very frequent, but a consistent cause of diarrhoea in humans (Koopmans et al., 1997; Waters et al., 2000) . M Petric has described the epidemiology of toroviruses (Section VI, Chapter 1). As molecular tests become available, the true extent of prevalence and incidence of human TV infections will become apparent.

Picobirnaviruses are related to, but not recognized yet as, members of the Birnaviridae family (Leong et al., 2000) . They comprise icosahedral, single shelled, non-enveloped particles which contain 2 segments of double stranded RNA as their genome. These viruses (diameter 60 nm) occur in three known genera: Aquabirnavirus (in fish; type species: infectious pancreatic necrosis virus, IPNV), Avibirnavirus (in birds; type species: infectious bursal disease virus, IBDV) and Entornobirnaviruses (in Drosophila; type species: Drosophila X virus (BXV); Leong et al., 2000) .

Picobirnaviruses are only 30-40 nm in diameter and have 2 (or sometimes 3) segments of dsRNA as their genome (Leite et al., 1990) . They were detected in children with diarrhoea and in several animal species (asymptomatic) (Pereira, 1991; Ludert et al., 1991; Gallimore et al., 1993 Gallimore et al., , 1995 . Recently they were found in the faeces of HIV-infected patients with diarrhoea more frequently than in HIV-infected patients without diarrhoea (Grohmann et al., 1993; Giordano et al., 1999) , but a virusspecific immune response was not measurable (Grohmann et al., 1993) . The viral genome has recently been cloned and sequenced, and reagents derived from this will help to unravel the epidemiology of picorbirnavirus (Rosen et al., 2000) . B I Rosen has reviewed aspects of the molecular biology and epidemiology of these viruses (Section VI, Chapter 2).

The genus Enterovirus of the Picornaviridae family contains a large number of species [polioviruses of types 1-3, Coxsackieviruses of groups A (24 types) and B (6 types) and echoviruses (>70 types), Melnick, 1996] . Enteroviruses consist of an almost featureless capsid of 27-30 nm diameter containing 60 protomers, each possessing 3 surface proteins, VP1, VP2, VP3, and, in most viruses, an internal capsid protein, VP4. The capsid encloses a genome of single stranded RNA of positive polarity of 7-8.5 kb length. The RNA has a single open reading frame (ORF) encoding a polyprotein precursor which is co-and post-translationally cleaved in a complex cascade of events into the 3 to 4 structural and a number of non-structural proteins (for details see Racaniello, 2001) .

All enteroviruses infect man via the gastrointestinal tract where they have their first site of replication, probably in lymphoid tissues of the pharynx and gut. Usually enteroviruses are excreted in the stool for several weeks after infection but can also be isolated easily from the pharynx. After primary replication viruses spread via blood to other organs (nerve, muscle, fatty tissue) where they replicate further. Most infections are asymptomatic, but enteroviruses can be the cause of meningitis, meningoencephalitis (poliomyelitis), myocarditis, pleurodynia, conjunctivitis and rashes (Melnick, 1996) .

In most cases of enterovirus infection there is no diarrhoea. However, some diarrhoea outbreaks have been found to be associated with enterovirus infections;

Coxsackievirus A1 and echoviruses of types 4, 11, 14, 18, 19 and 22 have been involved (Townsend et al., 1982; Patel et al. 1985; Melnick, 1996) .

Recently, echoviruses of types 22 and 23 have been removed from the Enterovirus genus and, as they are very different in their sequence from all other Picornaviridae, been classified in a separate genus Parechovirus (King et al., 2000) .

The Aichivirus is an at present unassigned species in the Picornaviridae family (King et al., 2000) , but is proposed as a separate new genus (Yamashita et al. 1998) . It is icosahedral, and the capsid has only 3 proteins. Virions are stable at pH 3.5. Aichivirus grows well in cell culture (BSC-1 and Veto cells) and has been shown to be a consistent cause of human gastroenteritis (Yamashita et al., 1991 (Yamashita et al., , 1993 . It has also been found as a cause of traveller's diarrhoea (Yamashita et al., 1995) . Its genome has recently been cloned and sequenced (Yamashita et al., 1998) , and it is hoped that the epidemiology of this virus will be further clarified with the availability of specific molecular reagents. T Yamashita and K Sakae have summarised our present knowledge of Aichivirus in Section VI, Chapter 3.

HIV, the causative agent of the Acquired Immunodeficiency Syndrome (AIDS), is a member of the Lentivirus genus of the Retroviridae family. It infects the CD4 subset of lymphocytes overwhelmingly, but also macrophages, using different sets of receptors/ coreceptors. Its replication (for details see Freed and Martin, 2001) damages the functions of infected cells before they are destroyed. The infection is symptomless for a long time, but then severe, generalised secondary infections appear (caused by other viruses, bacteria, fungi or protozoa) which are generally lethal.

There is evidence of extensive HIV infection in gut-associated lymphoid tissue (GALT) and also in enterocytes which contribute to the development of chronic diarrhoea in many AIDS patients (Nelson et al., 1988; Heise et al., 1991; Kotler et al., 1991; Rabeneck, 1994) .

Cytomegalovirus (CMV) and herpes simplex viruses, members of the Herpesviridae family, are found as the cause of colitis and oesophagitis, mainly in HIV-infected patients (Levinson and Bennets, 1985; Jacobson and Mills, 1988; Dieterich and Robinson, 1991; Theise et al. 1991; Mentec et al., 1994; Cotte et al., 1996) . With the application of highly active antiretroviral therapy (HAART) it has become less urgent or indicated to commence and maintain a specific anti-CMV therapy with ganciclovir (Whitcup et al., 1999; Pollok, 2001) .

Coronavirus is another genus of the Coronaviridae family (Enjuanes et al., 2000) . The particles are 120-160 nm is diameter, enveloped and possess a genome of linear. positive-sense, single stranded RNA of 27 -31 kb in size. The genome is surrounded by nucleocapsid protein (N; in helical symmetry) which in turn is contained in an envelope consisting of M protein and a host cell-derived lipid bilayer into which are inserted the surface proteins S (forming spikes), a small membrane protein (E) and the haemagglutinin esterase (HE) protein. Protein is expressed from RNA molecules which are in most cases subgenomic, and all mRNAs carry a leader sequence derived from the 5' end of the genome (for details see Lai and Holmes, 2001) .

Coronaviruses infect the respiratory and gastrointestinal tract. They are a recognized cause of common cold in man (McIntosh, 1996) . Whilst coronavirus infections are firmly associated with gastroenteritis in animals (e.g. Transmissible gastroenteritis virus (TGEV) of pigs; Kim et al., 2001) , their association with gastroenteritis in man has often been claimed, but its significance for human diarrhoeic disease has been controversial and not yet been firmly established (Gerna et al., 1985; Zhang et al., 1994; Siddell and Snijder, 1998; .

J Grant has produced a review of the histopathological findings of viral gastrointestinal tract infections, with particular emphasis on the data obtained from the immunocompromised (Section VI, Chapter 4).

Cytomegalovirus DNA level on biopsy specimens during treatment of cytomegalovirus gastrointestinal disease

Cytomagalovirus colitis in AIDS: presentation in 44 patients and a review of the literature

Coronaviridae

HIVs and their replication

Detection and characterization of bisegmented double stranded RNA viruses (Picobirnavirus) in human faecal specimes

Detection and characterization of a novel bisegmented double-stranded RNA virus (Picobirnavirus) from rabbit faeces

Human enteric coronaviruses: antigenic relatedness to human coronavirus OC43 and possible etiologic role in viral gastroenteritis

Diarrhea and enteric emerging viruses in HIV-infected patients

Enteric viruses and diarrhoea in HIV-infected patients

Human immunodeficiency virus infection of enterocytes and mononuclear cells in human jejunal mucosa

Coronaviruses. In: Fields' Virology

Serious cytomegalovirus disease in the acquired immunodeficiency syndrome (AIDS)

Differential detection of transmissible gastroenteritis virus and epidemic diarrhea virus by duplex RT-PCR

Picornaviridae

Association of torovirus with acute and persistent diarrhoea in children

Toroviruses of animals and humans: a review

Enzyme-linked immunosorbent assay reactivity of torovirus-like particles in fecal specimens of humans with diarrhea

Detection, localisation and quantitation of H/V-associated antigens in intestinal biopsies from patients with AIDS

Coronaviridae: The viruses and their replication

A novel avian virus with trisegmented double stranded RNA and further observations on previously described similar viruses with bisegmented genome

Birnaviridae

Cytomegalovirus colitis in acquired immunodeficiency -a chronic disease with varying manifestations

Identification in porcine faeces of a novel virus with a bisegmented double stranded RNA genome

Coronaviruses. In: Fields Virology, 3 '~ Edition

Enteroviruses: Polioviruses, Coxsackieviruses, echoviruses and newer enteroviruses

Cytomegalovirus colitis in HIV-1 infected patients: a prospective research in 55 patients

Human immunodeficiency virus detected in bowel epithelium from patients with gastrointestinal symptoms

An epidemic of acute diarrhoea in sural Southern India associated with echovirus type 11 infection

Double-stranded RNA viruses

Viruses causing diarrhoea in AIDS

AIDS enteropathy: What's in the name?

Picornaviridae: The viruses and their replication

Cloning of human picobirnavirus genomic segments and development of a RT-PCR assay

Coronaviruses, toroviruses and arteriviruses

The molecular biology of toroviruses

Cytomegalovirus esophagitis in AIDS diagnosis by endoscopic biopsy

Outbreak of Coxsackie A1 gastroenteritis; a complication of bone marrow transplantation

Etiology of community-acquired pediatric viral diarrhea: a prospective longitudinal study in hospitals, emergency departments, pediatric practices and child care centres during the winter rotavirns outbreak, 1997 to 1998. The Pediatric Rotavirus Epidemiology Study for Immunization Study Group

Discontinuation of anticytomegalovirus therapy in patients with HIV infection and cytomegalovirus retinitis

Isolation of cytopathic small round viruses with BSC-1 cells fi'om patients with gastroenteritis

Prevalence of newly isolated cytopathic small round virus (Aichi strain) in Japan

Isolation of cytopathic small round virus (Aichi virus) fro Pakistani children and Japanese travellers from South East Asia

Complete nucleotide sequence and genetic organization of Aichi virus, a distinct member of the Picornaviridae associated with acute gastroenteritis in humans

Biological and genetic characterization of haemagglutinating coronavirus isolated from a diarrhoeic child