Persistent gastroenteritis in children infected with astrovirus: Association with serotype‐3 strains

Caballero, Santiago; Guix, Susana; El‐Senousy, Waled M.; Calicó, I; Pintó, Rosa M.; Bosch, Albert

doi:10.1002/jmv.10476

Cited by 59 publications

(48 citation statements)

References 17 publications

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“…While the addition of EDTA to the purification buffers of sucrose gradients does not affect viral stabilization (6,8), its inclusion in our CsCl buffers completely destabilize VLPs. In fact, the addition of divalent cations (Ca 2ϩ and Mg 2ϩ ) in the purification solutions of CsCl gradients has been found to stabilize viral particles (22).…”

Section: Discussionmentioning

confidence: 84%

“…One-milliliter samples of astrovirus stocks, soluble fractions from infected Sf9 cell extracts, and concentrates of infected cell supernatants were loaded on the top of either preformed 0 to 45% (wt/wt) 9-ml sucrose gradients or preformed 0 to 50% (wt/wt) 9-ml CsCl gradients in TN buffer. Sucrose gradients were centrifuged for 2 h and 45 min at 200,000 ϫ g, and CsCl gradients were centrifuged for 18 h at 150,000 ϫ g as previously described (6). Gradients were fractionated, and the density for each fraction was estimated from the refraction index.…”

Section: Materials and Methods Cells And Virusesmentioning

confidence: 99%

See 1 more Smart Citation

Structural Requirements of Astrovirus Virus-Like Particles Assembled in Insect Cells

Caballero¹,

Guix²,

Ribes

et al. 2004

J Virol

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Expression of the complete ORF2 of human astrovirus serotype 1 (HAstV-1) in the baculovirus system led to the formation of virus-like particles (VLPs) of around 38 nm. The same kind of VLPs were also obtained either with the expression of a truncated form of ORF2 lacking the first 70 amino acids (aa), or with the same truncated form in which those 70 aa were replaced by the green fluorescent protein. All three kinds of VLPs were equally recognized by an anti-HAstV-1 polyclonal antibody and by two monoclonal antibodies (MAbs; 8E7 and 5B7), indicating a nonessential role of those amino acids neither in the capsid assembly nor in the antigen structure. A second type of structure consisting of 16-nm ring-like units was observed in all of the cases, mostly after disassembling the 38-nm VLPs through the addition of EDTA. The removal of the EDTA and the addition of Mg 2؉ ions promoted the reassembly of the 38-nm VLPs. The nature of these 16-nm ring-like structures, capsomers or T ‫؍‬ 1 VLPs, still remains unclear. Biochemical analysis revealed no differences between the 38-nm VLPs and the 16-nm structures, whereas antigenically, they shared the 8E7 MAb epitope but differed in the 5B7 MAb epitope, with the latter structures being more readily recognized.Human astroviruses (HAstV) are a frequent causal agent of gastroenteritis in children worldwide (5,10,12,14,24,27,28,35,38), although they have also been associated with the elderly (4, 29, 34). Eight serotypes have been described, with serotype 1 (HAstV-1) being the most globally prevalent (12,14,18,27,28,33,36). Astroviruses are nonenveloped viruses whose capsid is around 28 to 41 nm in diameter and contains a plus-sense single-stranded RNA of around 6.9 kb organized in three open reading frames (ORFs) (20,32,37). ORF1a and ORF1b encode the nonstructural proteins (19,21,22), whereas ORF2 encodes the structural proteins through a subgenomic RNA (25). ORF2 of HAstV-1 encodes a polyprotein of 787 amino acids (aa) in length, with a molecular mass of around 87 kDa (26), which is the precursor of the smaller 24-to 26-kDa, 29-to 31-kDa, and 32-to 34-kDa structural proteins (1,3,26). The proteolytical processing from the precursor to the mature structural proteins is still very controversial, and to date, three different models have been proposed (1,13,23). In the first model, Bass and Qiu (1) proposed an intracellular processing of the precursor polyprotein at the amino terminus between residues 70(R) and 71(K) before capsid assembly, with this capsid being further processed extracellularly by the action of trypsin and giving the above-mentioned mature proteins. In subsequent studies, the intracellular processing of this model was refused (13), with the complete precursor being the assembly unit. Later on, Méndez and colleagues (23) proposed a third model in which the structural precursor of HAstV-8 is intracellularly processed at the carboxy terminus prior to its assembly into the capsid, although the cleavage site has not yet been identified.The expression of the genomes en...

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Section: Discussionmentioning

confidence: 84%

Section: Materials and Methods Cells And Virusesmentioning

confidence: 99%

Structural Requirements of Astrovirus Virus-Like Particles Assembled in Insect Cells

Caballero¹,

Guix²,

Ribes

et al. 2004

J Virol

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“…Positive samples showing RT-PCR product bands in agarose gels were quantified by a competitive RT-PCR with primers A1/A2 in the presence of an internal RNA standard (internal control [IC]). This IC is a 511-mer RNA molecule containing a region complementary to the A2 primer and, at a distance of 135 nucleotides, a region identical to the A1 primer, thus establishing competitive conditions (5). The 135-bp IC amplimer is easily distinguishable from the viral amplimers, whose lengths range from 192 to 237 bp, depending on the strain (7).…”

Section: Methodsmentioning

confidence: 99%

Removal of Astrovirus from Water and Sewage Treatment Plants, Evaluated by a Competitive Reverse Transcription-PCR

El‐Senousy

Guix

Abid

et al. 2007

Appl Environ Microbiol

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Quantification of human astrovirus genogroups A and B was undertaken with sewage and water samples, collected from the Greater Cairo area in Egypt from November 1998 to October 1999, by a competitive reverse transcription (RT)-PCR with an internal control. The number of RNA copies of genogroup A/liter in quantifiable samples ranged from 3.4 × 103 to 5.6 × 106 in raw sewage and from 3.4 × 103 to 1.1 × 104 in treated effluents, while the number of infectious units per liter in these samples as determined by cell culture RT-PCR (CC-RT-PCR U/liter) ranged from 3.3 × 101 to 3.3 × 103 in raw sewage and was 3.3 × 100 in treated effluents. On the other hand, the number of RNA copies/liter in quantifiable genogroup B samples ranged from 1.1 × 104 to 8.7 × 106 in raw sewage and from 1.1 × 103 to 6.2 × 105 in treated effluents, while the number of infectious units ranged from 3.3 × 101 to 3.3 × 105 CC-RT-PCR U/liter in raw sewage and from 3.3 × 101 to 3.3 × 102 CC-RT-PCR U/liter in treated effluents. These higher numbers of both RNA copies/liter and infectious particles of genogroup B may indicate the emergence of genogroup B in the area. Additionally, genogroup B astrovirus exhibited a higher resistance to removal treatments with regard to the number of RNA copies per ml. When the equipment for real-time approaches is unavailable, a competitive PCR or RT-PCR with an internal control may be employed for virus quantification in validations of the efficiency of virus removal treatments.

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“…In one study, quantification of shedding levels of serotypes 1, 2, 3, 4, and 8 ascertained viral concentrations ranging from 3.4 ϫ 10 8 to 1 ϫ 10 13 per gram of feces and significantly higher titers in the serotype 3-containing feces. In addition, serotype 3 was associated with a more severe gastroenteritis (104). Later on, differences in viral load in fecal samples were further associated with variability in one of the viral nonstructural proteins, the nsP1a/4 protein (60), suggesting that nonstructural proteins may also influence the pathogenicity of the HAstV strain.…”

Section: Clinical Disease Correlatesmentioning

confidence: 99%

“…Figure 7 depicts the potential environmental routes of HAstV transmission. HAstV may be shed in very high numbers, reaching up to 10 13 genome copies per gram, in the stools of infected individuals (104). Since wastewater treatment practices do not ensure the complete removal of viral pathogens, HAstV present in untreated and treated wastewaters are discharged into the environment (214-217) and may become contaminants of marine water, freshwater, and groundwater (211,218).…”

Section: Epidemiology Hastv Transmissionmentioning

confidence: 99%

Human Astroviruses

2014

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SUMMARY Human astroviruses (HAtVs) are positive-sense single-stranded RNA viruses that were discovered in 1975. Astroviruses infecting other species, particularly mammalian and avian, were identified and classified into the genera Mamastrovirus and Avastrovirus . Through next-generation sequencing, many new astroviruses infecting different species, including humans, have been described, and the Astroviridae family shows a high diversity and zoonotic potential. Three divergent groups of HAstVs are recognized: the classic ( MAstV 1 ), HAstV-MLB ( MAstV 6 ), and HAstV-VA/HMO ( MAstV 8 and MAstV 9 ) groups. Classic HAstVs contain 8 serotypes and account for 2 to 9% of all acute nonbacterial gastroenteritis in children worldwide. Infections are usually self-limiting but can also spread systemically and cause severe infections in immunocompromised patients. The other groups have also been identified in children with gastroenteritis, but extraintestinal pathologies have been suggested for them as well. Classic HAstVs may be grown in cells, allowing the study of their cell cycle, which is similar to that of caliciviruses. The continuous emergence of new astroviruses with a potential zoonotic transmission highlights the need to gain insights on their biology in order to prevent future health threats. This review focuses on the basic virology, pathogenesis, host response, epidemiology, diagnostic assays, and prevention strategies for HAstVs.

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Persistent gastroenteritis in children infected with astrovirus: Association with serotype‐3 strains

Cited by 59 publications

References 17 publications

Structural Requirements of Astrovirus Virus-Like Particles Assembled in Insect Cells

Structural Requirements of Astrovirus Virus-Like Particles Assembled in Insect Cells

Removal of Astrovirus from Water and Sewage Treatment Plants, Evaluated by a Competitive Reverse Transcription-PCR

Human Astroviruses

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