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S Urasawa

Publications and source records attributed to S Urasawa.

154 records · Page 9Linked to original sources
PubMedDate not supplied

Non-random selection of gene segment 3 and random selection of gene segment 5 observed in reassortants generated in vitro between rotavirus SA11 and RRV.

A total of 154 clones of reassortants between rotavirus RRV and SA11 were isolated in vitro in order to compare the selection modes of each RNA segment in reassortant formation with those in the in vivo experiment (carried out by Gombold and Ramig) using the same parent strains in which the occurrence of non-random selection of gene segments 3 and 5 was observed. In reassortants isolated from a cross RRV x SA11-L2 (66 isolates) and a cross RRV x SA11-S1 (88 isolates), 36 and 57 different genotypes were identified, respectively. Segregation rates of SA11 RNA segments 1, 5, 8, 9 and 11 were significantly different as compared with those previously reported in the in vivo experiment. While RNA segment 3 was preferentially selected from an SA11 parent, the segregation rate of SA11 gene 5 was relatively low in vitro. Thus, the selection mode of rotavirus RNA segments was found to be different between in vivo and in vitro reassortments.

Animals↗
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Preferential selection of specific rotavirus gene segments in coinfection and multiple passages with reassortant viruses and their parental strain.

We previously reported non-random selections of human rotavirus (HRV) Wa genes 2 and 5 in reassortant formation between HRV strains Wa and HN126 under selection pressure with neutralizing monoclonal antibodies. In order to study whether or not these genes are preferentially selected in the genetic background of a parental strain HN126 in vitro without selection pressures, coinfection and multiple passage experiments were performed between HN126 and one of three reassortants, C1, C1T and C1F; C1 possessed genes 2 and 5 derived from Wa and the other genes derived from HN126, while C1T and C1F were single gene reassortants having Wa gene 2 or Wa gene 5 in the genetic background of HN126, respectively. When MA-104 cells were coinfected with the same infectious units of HN126 and C1, Wa genes 2 and 5 of reassortant C1 became predominant within 10 repeated passages, although Wa gene 5 was selected more preferably than Wa gene 2. Similar results were obtained under different experimental conditions in which different doses of parental strains or different type of cells were used. Also, in coinfections of MA-104 cells with HN126 and C1T, or HN126 and C1F, Wa gene 2 or Wa gene 5 became predominant at the sixth passage. Analysis of viral growth curves indicated that two reassortants, C1 and C1F, replicated to a titre higher than HN126, while no difference in viral growth was observed between C1T and HN126. These results indicated that in the genetic background of HN126, Wa gene 5 might provide viruses with a growth advantage compared with its HN126 counterpart, while Wa gene 2 might be preferentially selected into reassortant clones through its greater functional capacity for assortment during viral replication.

Animals↗
PubMedDate not supplied

Reactivity of anti-human rotavirus VP4 neutralizing monoclonal antibodies with animal rotaviruses and with unusual human rotaviruses having different P and G serotypes.

The reactivity of five anti-human rotavirus VP4 neutralizing monoclonal antibodies (N-mAb) with 20 animal rotavirus strains and three unusual human rotavirus (HRV) strains was investigated. Five N-mAb prepared previously by the immunization of mice with HRV were employed in this study. They were found to neutralize HRV belonging to P types 4, 6 and 8, which were designated according to P (or VP4) type nomenclature proposed by Estes and Cohen (1989). A porcine rotavirus strain Gottfried was reactive with four of the five mAb both in neutralization tests and in ELISA. However, no other animal rotaviruses were neutralized by any of the mAb. Fourteen animal strains were reactive with only one or two mAb in ELISA, and five animal strains were inactive with all. These results indicate that neutralization epitopes on VP4 are serologically considerably different between HRV (except for unusual Indonesian strains 57M and 69M) and animal rotaviruses (except for porcine rotavirus strain Gottfried).

Aged↗
PubMedDate not supplied

Analysis of gene selection in reassortant formation between canine rotavirus K9 and human rotaviruses with different antigenic specificities.

A number of antigenic mosaic reassortants which have neutralization proteins VP4 and VP7 derived from different parental strains were analysed in order to study gene selection in reassortant formation between animal and human rotaviruses (HRV). These reassortants were isolated from mixed infection of MA-104 cells with canine rotavirus strain K9 (subgroup I and G serotype 3) and HRV strains (with subgroup I or II antigen and G serotype 1-4, 9 or 12 antigen), through repeated selections with anti-VP4 and anti-VP7 neutralizing monoclonal antibodies directed specifically at HRV and K9, respectively. By serological and genomic analyses, all the isolated clones were found to be antigenic mosaic reassortants possessing VP4 of K9 and VP7 of HRV. In the reassortants between strain K9 and one of the six strains of subgroup II HRV, a single or a few genotypes with particular constellations of RNA segments were predominant, with only a few RNA segments including gene 4 (encoding VP4) being derived from K9. In contrast, in the reassortants between strain K9 and any one of the subgroup I HRV, more than nine different genotypes were identified and various RNA segments, except for segments 8 and 10, were derived from K9. These findings indicated that the RNA segments of K9 might be reassorted more readily with those of subgroup I HRV than with those of subgroup II HRV, suggesting the possible existence of functional mechanisms which determine the extent of diversity of genome selection depending on the pairs of parent strains in the reassortant formation.

Animals↗
PubMedDate not supplied

Genomic relatedness of five equine rotavirus strains with different G serotype and P type specificities.

Overall genomic relatedness among five equine rotavirus strains and their relatedness to representative human and animal rotavirus strains were investigated by RNA-RNA hybridization tests. The genomes of strains FI-14, FI-23 and H2 were highly related to one another. Strain L338 had only a low degree of genomic relatedness to the other four equine rotavirus strains. Strain H1 also showed little genetic relatedness to the other equine strains. The genome of the strain H1, however, was highly related to those of porcine rotavirus strains OSU, Gottfried and YM. Genomic relatedness of four equine rotavirus strains (FI-14, FI-23, H2 and L338) to human and other animal rotavirus strains was low, whereas several RNA segments of strain H1 showed a relatedness to those of human strain Wa.

Animals↗
PubMedDate not supplied

Genotypic diversity of reassortants between simian rotavirus SA11 and human rotaviruses having different antigenic specificities and RNA patterns.

A total of 200 clones of reassortants were generated in vitro between simian rotavirus SA11 (SA11-L2 strain) and each of five human rotavirus (HRV) strains with different antigenic specificities and RNA patterns. When culture fluid coinfected with parent viruses was subjected to repeated selection with anti-HRV-VP4 and anti-SA11-VP7 neutralizing monoclonal antibodies, all yielded progenies were antigenic mosaic reassortants possessing VP4 and VP7 derived from SA11 and HRV, respectively. In genomic analysis of viral RNA by PAGE, two and five different genotypes were identified in 40 clones, generated between SA11 and HRV strain Hochi (G serotype 4, G4) and between SA11 and KU (G1), respectively. In contrast, 11 and 17 genotypes were found in progenies between SA11 and subgroup I G2 HRV strain HN126 or DS-1, respectively. Although SA11 genes, except for the VP7 gene, were predominant in most reassortants, gene 5 was preferentially selected from HRV. Incorporation of HRV segments 1, 3 and 10 into progenies was more frequent in SA11 x HN126 and SA11 x DS-1 reassortants than in other reassortants. These results indicated that the extent of diversity of reassortant genotypes differs between the two groups of the parental HRV strain; one has subgroup I specificity and a short RNA pattern (DS-1 genogroup), while the other has subgroup II specificity and a long RNA pattern (Wa genogroup).

Animals↗
PubMedDate not supplied

Serotyping of human rotavirus by enzyme immuno-assay with monoclonal antibodies.

Two series of enzyme immunoassays with monoclonal antibodies produced in two laboratories (A and B) were compared in use for serotyping of human rotavirus in stool samples collected in Japan between 1988 and 1991 from patients with gastroenteritis. Of 358 samples, 222 were determined to be the same serotype, while 61 samples could not be serotyped by either assay. A hundred and one and 92 samples were not serotyped by the A and B antibodies, respectively. We believe that the A and B monoclonal antibodies are useful clinically for serotyping rotaviruses at the present time.

Antibodies, Monoclonal↗