Studies on the Influence of the VP7 Gene on Rotavirus Replication

Xu, Zhichang; Woode, G. N.

doi:10.1006/viro.1994.1049

Cited by 17 publications

(6 citation statements)

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“…In addition, it has been reported that specific phenotypes, such as plaque size and protease dependence of growth, associated with the outer capsid proteins, can be affected in rotavirus reassortants by the recipient genetic background, and specific interactions between VP4 and VP7 have been proposed as the basis for these phenotypic effects (7). Furthermore, growth competition experiments have suggested that VP7 can provide replication advantages to reassortant viruses, and it was speculated that VP7 caused this effect possibly by modifying VP4 to make it adsorb more efficiently to cell receptors (42).…”

Section: Fig 2 Effect Of Neuraminidase Treatment Of Ma104 Cells On mentioning

confidence: 99%

Interactions between the two surface proteins of rotavirus may alter the receptor-binding specificity of the virus

Méndez

Arias

1996

J Virol

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The infection of target cells by most animal rotavirus strains requires the presence of sialic acids (SAs) on the cell surface. We recently isolated variants from simian rotavirus RRV whose infectivity is no longer dependent on SAs and showed that the mutant phenotype segregates with the gene coding for VP4, one of the two surface proteins of rotaviruses (the other one being VP7). The nucleotide sequence of the VP4 gene of four independently isolated variants showed three amino acid changes, at positions 37 (Leu to Pro), 187 (Lys to Arg), and 267 (Tyr to Cys), in all mutant VP4 proteins compared with RRV VP4. The characterization of revertant viruses from two independent mutants showed that the arginine residue at position 187 changed back to lysine, indicating that this amino acid is involved in the determination of the mutant phenotype. Surprisingly, sequence analysis of reassortant virus DS1XRRV, which depends on SAs to infect the cell, showed that its VP4 gene is identical to the VP4 gene of the variants. Since the only difference between DS1XRRV and the RRV variants is the parental origin of the VP7 gene (human rotavirus DS1 in the reassortant), these findings suggest that the receptor-binding specificity of rotaviruses, via VP4, may be influenced by the associated VP7 protein.

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Section: Fig 2 Effect Of Neuraminidase Treatment Of Ma104 Cells On mentioning

confidence: 99%

Interactions between the two surface proteins of rotavirus may alter the receptor-binding specificity of the virus

Méndez

Arias

1996

J Virol

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confidence: 99%

“…Rotaviruses may enter either through an endocytotic pathway or through direct penetration. Although earlier studies implicated VP7 in cell attachment (19,46), recent studies have increasingly indicated that VP4 is the major player in the entry process (11,26,30) while VP7 may modulate the functions of VP4 (3,10,35,49).VP4 is susceptible to proteolysis and is cleaved by trypsin into VP8 ‫ء‬ (26 kDa) and VP5 ‫ء‬ (60 kDa). The two trypsin cleavage products remain associated with the virion, although the precise topographical locations of VP5 ‫ء‬ and VP8 ‫ء‬ in the VP4 spike are still uncertain.…”

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confidence: 99%

Trypsin Cleavage Stabilizes the Rotavirus VP4 Spike

Crawford¹,

Mukherjee²,

Estes³

et al. 2001

J Virol

126

103

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Trypsin enhances rotavirus infectivity by an unknown mechanism. To examine the structural basis of trypsin-enhanced infectivity in rotaviruses, SA11 4F triple-layered particles (TLPs) grown in the absence (nontrypsinized rotavirus [NTR]) or presence (trypsinized rotavirus [TR]) of trypsin were characterized to determine the structure, the protein composition, and the infectivity of the particles before and after trypsin treatment. As expected, VP4 was not cleaved in NTR particles and was cleaved into VP5‫ء‬ and VP8 ‫ء‬ in TR particles. However, surprisingly, while the VP4 spikes were clearly visible and well ordered in the electron cryomicroscopy reconstructions of TR TLPs, they were totally absent in the reconstructions of NTR TLPs. Biochemical analysis with radiolabeled particles indicated that the stoichiometry of the VP4 in NTR particles was the same as that in TR particles and that the VP8 ‫ء‬ portion of NTR, but not TR, particles is susceptible to further proteolysis by trypsin. Taken together, these structural and biochemical data show that the VP4 spikes in the NTR TLPs are icosahedrally disordered and that they are conformationally different. Structural studies on the NTR TLPs after trypsin treatment showed that spike structure could be partially recovered. Following additional trypsin treatment, infectivity was enhanced for both NTR and TR particles, but the infectivity of NTR remained 2 logs lower than that of TR particles. Increased infectivity in these particles corresponded to additional cleavages in VP5 ‫ء‬ , at amino acids 259, 583, and putatively 467, which are conserved in all P serotypes of human and animal group A rotaviruses and also corresponded with a structural change in VP7. These biochemical and structural results show that trypsin cleavage imparts order to VP4 spikes on de novo synthesized virus particles, and these ordered spikes make virus entry into cells more efficient.Rotaviruses are the leading cause of severe gastroenteritis in young children worldwide (16). Structural and biochemical analyses show that rotaviruses are large, icosahedral particles having a complex architecture consisting of three concentric capsid layers surrounding a genome of 11 segments of doublestranded RNA (41, 42). The innermost capsid layer, composed of VP2, encloses the genomic double-stranded RNA. A significant portion of the genomic RNA, particularly that in close contact with the inner surface of the VP2 layer, is icosahedrally ordered (43). Anchored to the inner surface of VP2 at the icosahedral vertices are two proteins, VP1 and VP3, involved in transcription of the genome within the intact particle. The intermediate capsid layer is composed of trimers of VP6 organized on a Tϭ13 (levo) icosahedral lattice (44). The outermost layer in the infectious virus is composed of the major capsid glycoprotein VP7 and the hemagglutinin spike protein VP4 (16). VP7 is present as 780 molecules grouped as 260 trimers at the local and strict threefold axes of a Tϭ13 left-handed icosahedral lattice (44, 51). The VP7 ...

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“…It was also observed that the reactivity of the monoclonal antibodies to the VP7 epitopes can also be influenced by the VP4 origin (Dunn et al, 1994). Furthermore, competitive growth experiments have suggested that VP7 can provide replication advantages to the reassortant, probably by modification of VP4 that can then adsorb more efficiently to the cell receptor (Xu and Woode, 1994). Consequently, some combinations such as the P[11],G8 genotype observed in this work may be more frequent than others within a herd.…”

Section: Discussionmentioning

confidence: 68%

G and P Genotypes of Group A Rotavirus from Diarrhoeic Calves Born to Cows Vaccinated against the NCDV (P[1],G6) Rotavirus Strain

Barreiros

Alfieri

Médici

et al. 2004

Journal of Veterinary Medicine, Series B

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A total of 71 group A rotavirus field strains, detected by polyacrylamide gel electrophoresis and enzyme immune assay, were submitted to genotyping by a multiplex nested-reverse transcription-polymerase chain reaction (RT-PCR). Faecal samples were obtained from calves with diarrhoea, between January 2000 and December 2001, from 14 dairy and beef cattle herds located in Mato Grosso do Sul, Sa˜o Paulo and Parana´States, Brazil. Thirty-five rotavirus field strains were detected in faeces from calves born to vaccinated dams with inactivated commercial vaccine containing the rotavirus strain P[1],G6 from seven herds while 36 rotavirus field strains were obtained from diarrhoeic calves from other seven herds without rotavirus vaccination. Identification of P and G rotavirus genotypes was possible in 94.3% (67/71) of the strains. However, G genotype could not be identified in two strains, P genotype in another strain and both genotypes were not detected in a third strain. P and G rotavirus genotype associations were identified in rotavirus field strains from non-vaccinated and vaccinated herds at similar rates of 94.4% (34/36) and 94.3% (33/35), respectively. In non-vaccinated herds binary combinations were P[1],G6 (three herds; 12 strains), P[1],G8 (three herds; six strains), P[5],G6 (two herds; 10 strains) and P[11],G8 (one herd; four strains). The genotype P[11],G6 was the most frequent (three herds; 12 strains) in vaccinated herds, followed by P[5],G6 (two herds; three strains), and P[11],G8 (two herds; eight strains). Mixed infections were observed in one non-vaccinated herd (two strains) and in four vaccinated herds (10 strains). Identification of binary combinations was not possible in one strain from nonvaccinated herds and two strains from vaccinated herds. Unusual genotypes were more frequent (91.4%) in nonvaccinated herds than those from prototypes of bovine rotavirus strains. Nebraska calf diarrhoea virus (NCDV)-like genotype was found in none of the rotavirus field strains detected in diarrhoeic calves born of vaccinated dams.

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Studies on the Influence of the VP7 Gene on Rotavirus Replication

Cited by 17 publications

References 0 publications

Interactions between the two surface proteins of rotavirus may alter the receptor-binding specificity of the virus

Interactions between the two surface proteins of rotavirus may alter the receptor-binding specificity of the virus

Trypsin Cleavage Stabilizes the Rotavirus VP4 Spike

G and P Genotypes of Group A Rotavirus from Diarrhoeic Calves Born to Cows Vaccinated against the NCDV (P[1],G6) Rotavirus Strain

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