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Biomedical subjects

S Urasawa

Publications and source records attributed to S Urasawa.

At least 55 records · Page 3Linked to original sources
PubMed1994

Species specificity and interspecies relatedness in VP4 genotypes demonstrated by VP4 sequence analysis of equine, feline, and canine rotavirus strains.

We determined the nucleotide and deduced amino acid sequences of the VP4 genes of five equine, two feline, and two canine rotavirus strains. A high degree of homology (> 97.0%) was found among the VP4 amino acid sequences of the equine strains H2, FI-14, and FI23. Equine strain L338 has a distinct VP4 amino acid sequence from those of the other equine strains (78.1% or less homology), and the L338 VP4 exhibited more than 17.0% divergence at the amino acid level from those of rotavirus strains published so far. The VP4 amino acid sequence of equine strain H1, which showed low homology with those of other equine strains, shares > 95.4% homology to those of porcine strains OSU and YM. VP4 amino acid sequences of feline strain Cat97 and canine strains CU-1 and K9 showed a high degree of homology (96.8 to 97.2%) to one another, and were found to be quite similar (96.0-97.0% homology) to that of a human HCR3 strain recently characterized. Feline strain Cat2, whose VP4 sequence is distinct from that of strain Cat97, has a VP4 similar to those of human strains K8 and AU-1 (97.8 and 97.5% homologies at amino acid level, respectively). Thus, the VP4 sequences of rotaviruses showed species specificity and interspecies relatedness.

Amino Acid Sequence↗
PubMed1994

Differences in plaque size and VP4 sequence found in SA11 virus clones having simian authentic VP4.

We isolated five stable SA11 clones (TN-S1, TN-S2, TN-L1, TN-L2, and BN-S4) with different plaque sizes from two SA11 stocks. In polyacrylamide gel electrophoresis, the mobilities of the fourth, fifth, and seventh RNA segments of SA11 clones with large plaque size (TN-L1 and TN-L2) were faster than those of clones with small plaque size (TN-S1, TN-S2, and BN-S4). Nucleotide sequence determination of the fourth RNA segment identified a five-amino-acid difference in VP4s between the clones with large and small plaque sizes. The VP4 sequences of two clones with small plaque size (TN-S1 and BN-S4) were the same as the sequence of SA11-SEM reported by K. Nishikawa et al. (1988, J. Virol. 62, 4022-4026), while the VP4 sequences of the clones with large plaque size (TN-L1 and TN-L2) were similar, but not identical, to that reported by D. B. Mitchell and G. W. Both (1989, Nucleic Acids Res., 17, 2122). A single-gene reassortant, K8-L2.4, in which RNA segment 4 was derived from clone TN-L2 of SA11 virus and the other RNA segments were from strain K8, produced large plaques like TN-L2, suggesting that the five-amino-acid difference in VP4 between the clones with large and small plaque sizes might be associated with the difference in plaque size.

Animals↗
PubMed1994

Effect of the selection pressure with anti-VP7 and anti-VP4 neutralizing monoclonal antibodies on reassortant formation between two human rotaviruses.

In order to study the effect of selection pressure of anti-VP4 and anti-VP7 neutralizing monoclonal antibodies(N-MAbs) on reassortant formation, 424 reassortant clones were produced from mixed cultures of human rotavirus strains Wa and HN126 and their genotypes were analysed. Reassortant selection was done with four types of N-MAb: anti-VP4 MAb to Wa and anti-VP7 MAb to HN126(selection A); anti-VP4 MAb to HN126 and anti-VP7 MAb to Wa(selection B); anti-VP7 MAb to Wa(selection C); and anti-VP4 MAb to Wa(selection D). In each selection experiment, more than 100 clones were isolated, and the parental origin of RNA segments was identified by polyacrylamide gel electrophoresis. All clones isolated by selections A and B were found to be antigenic mosaic reassortants with the VP4 gene of HN126 and the VP7 gene of Wa and antigenic mosaic reassortants with the VP4 gene of Wa and the VP7 gene of HN126, respectively. Although in reassortants of both selections, RNA segments 2, 3, 5 and 6 were selected from strain Wa at considerably high rates, selection rates of RNA segments 1, 7, 8, and 11 were significantly different between selection A and B. In reassortants from selection C and D, selection rates of RNA segments 1, 3, 6, 7, 8, and 11 from Wa were significantly lower than those in selection A and B, whereas RNA segments 2 and 5 were almost exclusively selected from Wa as observed in selection A and B. These results indicated the presence of two types of nonrandom gene selection in reassortant formation, one strongly dependent on, and another irrespective of, the selection pressure with N-MAbs.

Antibodies, Monoclonal↗
PubMed1994

Survey on the distribution of the gene 4 alleles of human rotaviruses by polymerase chain reaction.

The presence of six gene 4 alleles (or VP4 genotypes) in human rotaviruses has been recognized. Using 16 representative cultivable human rotavirus strains, we confirmed the specificity of VP4 genotyping by polymerase chain reaction (PCR) using the nested oligonucleotides specific to each of the four representative gene 4 alleles. Using the PCR, we surveyed the gene 4 alleles of 199 human rotaviruses in stools collected in Japan and Thailand. Strains with the gene 4 allele, corresponding to P1A serotype, were shown to be the most prevalent, but two strains with P2 gene 4 allele and one strain with P3 gene 4 allele were detected in Thailand and in Japan, respectively.

Alleles↗
PubMed1994

Detection of mecA, femA, and femB genes in clinical strains of staphylococci using polymerase chain reaction.

MecA, a structural gene located on the chromosome of Staphylococcus aureus, characterizes methicillin-resistant S. aureus (MRSA), and femA and femB(fem) genes encode proteins which influence the level of methicillin resistance of S. aureus. In order to examine effectiveness of detecting mecA and fem genes in identification of MRSA, the presence of these genes in 237 clinically isolated strains of staphylococci was investigated by polymerase chain reaction (PCR). An amplified mecA DNA fragment of 533 base pairs (bp) was detected in 100% of oxacillin-resistant S. aureus, in 16.7% of oxacillin-sensitive S. aureus, in 81.5% of S. epidermidis, and in 58.3% of other coagulase-negative staphylococci (CNS). While the PCR product of femA (509 bp) or femB (651 bp) was obtained from almost all the S. aureus strains except for five oxacillin-resistant strains (2.5%), neither of these genes were detected in CNS. Therefore, the detection of femA and femB together with mecA by PCR was considered to be a more reliable indicator to identify MRSA by differentiating it from mecA-positive CNS than single detection of mecA.

Base Sequence↗
PubMed1993

Nucleotide sequence of VP4 and VP7 genes of a unique human rotavirus strain Mc35 with subgroup I and serotype 10 specificity.

The VP7 and VP4 genome segments of human rotavirus strain Mc35 (Urasawa et al., J. Infect. Dis. 166, 227-234, 1992) were investigated. Analysis of its VP7 nucleotide and amino acid sequences confirmed that it belongs to G (or VP7) serotype 10; however, the nucleotide sequence homologies between Mc35 and the four G10 bovine strains examined were lower than those among the four G10 bovine strains. The VP4 nucleotide and amino acid sequences of Mc35 were distinct (66.1-68.8% nucleotide and 64.9-70.0% amino acid homologies) from those of previously reported human and animal rotavirus strains representing different P (or VP4) types except for the strain K8 VP4, which was designated as type 3 of human rotavirus VP4 by Gorziglia et al. (Proc. Natl. Acad. Sci. USA., 87, 7155-7159, 1990). The VP4s of the K8 and Mc35 strains showed a relatively high degree of homology (77.6% nucleotide and 86.0% amino acid sequence homologies) and were presumed to represent subtypes of type 3 human rotavirus VP4 (type 3A (K8 VP4) and type 3B (Mc35 VP4)).

Amino Acid Sequence↗
PubMed1993

Efficient production of antigenic mosaic reassortants of rotavirus with the aid of anti-VP4 and anti-VP7 neutralizing monoclonal antibodies.

Anti-VP4 and anti-VP7 neutralizing monoclonal antibodies (N-MAbs) were used to select efficiently antigenic mosaic reassortants of rotavirus whose VP4 and VP7 are derived from parental strains having different antigenic specificities of VP4 and VP7. Under the selective pressure of anti-simian rotavirus (SA11) VP7 N-MAb and anti-human rotavirus (Wa or S2) VP4 N-MAb, all the clones isolated after mixed infection with SA11 and human rotavirus were found to be reassortants having VP4 of SA11 and VP7 of Wa or S2 by serological and genomic analyses. Two reassortants isolated from the mixed infection with SA11 and S2 had a segment whose different migration in polyacrylamide gel was different from those of any RNA segments of the parent strains, suggesting the occurrence of rearrangement in the process of reassortment.

Antibodies, Monoclonal↗
PubMed1993

Distinct yearly change of serotype distribution of human rotavirus in Thailand as determined by ELISA and PCR.

A total of 241 group A rotavirus-positive stool samples collected from diarrhoeic patients in Thailand between July 1988 and June 1991 were characterized for their serotypes by enzyme-linked immunosorbent assay (ELISA) using serotype-specific monoclonal antibodies and by a polymerase chain reaction (PCR). In July 1988-June 1989, serotype 1 was the most prevalent (63.4%), followed by serotype 4 (11.0%) and serotype 2 (8.5%). In July 1989-June 1990, 59.8% were serotype 1, 24.3% were serotype 2, and 6.1% were serotype 3. In contrast, in July 1990-June 1991, serotype 3 was detected in the highest frequency (40.5%), 29.9% were serotype 1, and 27.3% were serotype 2. Thus, a distinct yearly change of serotype distribution of rotavirus in Thailand was observed in the three consecutive years. In particular, it was of note that the prevalence of serotype 3 greatly increased, in contrast to the previous studies in which almost no serotype 3 rotaviruses were detected in the years 1983-8 in Thailand.

DNA, Viral↗
PubMed1993

Independent segregation of the VP4 and the VP7 genes in bovine rotaviruses as confirmed by VP4 sequence analysis of G8 and G10 bovine rotavirus strains.

We determined the complete nucleotide sequences of the VP4 genes of five bovine rotavirus strains (A5, 61A, A44, B223 and KK3). The deduced VP4 amino acid sequence of strain A5 with G8 serotype specificity is 91.1% identical to that of strain NCDV of the serotype G6, and strain 61A with G10 serotype specificity has a VP4 amino acid sequence (95.2% identity) similar to that of the UK strain of the G6 serotype. In contrast, the VP4 amino acid sequences of strains A44, B223 and KK3 of the G10 serotype, isolated in Thailand, the U.S.A. and Japan respectively, have very similar sequences to each other, but less similarity (50 to 60%) to other group A rotavirus strains reported so far. Their VP4 genes are 2352 nucleotides in length and encode 772 amino acids, four amino acids fewer than the VP4 proteins of other animal rotaviruses. Thus, the presence of three different VP4 types (P types) and the independent segregation of G serotype and P type were postulated in bovine rotaviruses by VP4 sequence analysis.

Amino Acid Sequence↗
PubMed1993

A minor prevalent strain in a severe outbreak of foal diarrhea associated with serotype 3 rotavirus.

An epizootic of foal diarrhea due to serotype 3 rotavirus (RV) was observed in 89 of 168 cases (53%) during the period from March to July in 1987. A total of 51 strains of RV were isolated from the 62 diarrheal feces examined, and one isolate (CH-3) showed a unique electropherotype of viral RNA which differed from the others that widely prevailed on this farm. No positive reaction was observed between strain CH-3 and each of the antisera against serotypes 1 to 12 of human and animal RV in neutralization tests. However, dsRNAs of the CH-3 virus were hybridized with a probe prepared from a strain of equine serotype 3 RV.

Animals↗
PubMed1993

The effect of food chemicals on cell aging of human diploid cells in in vitro culture.

The potency of food chemicals to induce cell aging was evaluated in human diploid fibroblast cells HAIN-55 having a finite replicative potential by using in vitro aging markers, i.e., decreases of maximum proliferative potential (lifespan) of cells, saturation density in monolayer culture (SD), plating efficiency (PE) and mitotic index (MI), and an increase of cells with polyploid karyotypes. By treatment twice with low concentration of genotoxic chemicals aflatoxin B1, allylisothiocyanate or trans-cinnamaldehyde (severe clastogenic flavoring agent; Kasamaki et al., 1982), lifespan (expressed by the number of cumulative cell population doubling (CPD)) of the treated cells was reduced by 8-12 CPDs accompanied by change of the other aging markers. By successive treatment (29 or 25 times) with non-genotoxic chemical aspartame (N-L-aspartyl-L-phenylalanine) or L-canavanine (structural analogue of L-arginine), lifespan of the treated cells was also slightly shortened (by 2-6 CPDs) compared with the untreated control cells. In the process of cell aging, Mitochondrial activity (MTT activity) decreased almost in parallel with the decrease of SD and MI. On the basis of these results, a variety of genotoxic and non-genotoxic chemicals were examined by using MTT activity as the aging marker for their effects on the aging of HAIN-55 cells and bovine artery endothelial cells which also had a finite replicative potential. The results showed that seven genotoxic and nine non-genotoxic chemicals promoted cell aging.

Aflatoxin B1↗
PubMed1992

Identification of human and bovine rotavirus serotypes by polymerase chain reaction.

The use of the polymerase chain reaction (PCR) for identifying serotypes of human and bovine rotaviruses was examined. In the identification of 115 human rotavirus samples in stools, results with PCR showed excellent agreement with results of serotyping by an enzyme-linked immunosorbent assay (ELISA) using serotype-specific monoclonal antibodies. Furthermore, the PCR showed a much higher sensitivity (93%) than the ELISA test (82.6%). The PCR method could also be applied for identifying the serotype of bovine rotaviruses.

Animals↗
PubMed1992

Antigenic and genetic analyses of human rotaviruses in Chiang Mai, Thailand: evidence for a close relationship between human and animal rotaviruses.

Serotyping of group A rotaviruses obtained from stools of 158 diarrheic patients in Chiang Mai, Thailand, by ELISA with monoclonal antibodies revealed a yearly change in the prevalence of individual serotypes. Three unusual human rotavirus strains were isolated. Strain Mc35 had subgroup I-serotype 10 antigen and a long RNA electrophoretic type, a property hitherto found only in bovine rotaviruses. RNA-RNA hybridization tests showed that the strain is more closely related genetically to bovine than to human rotaviruses. Strain Mc323, although serologically closely related to serotype 9, had subgroup I specificity and a long RNA electrophoretic type, a characteristic common to nonhuman rotaviruses. Strain Mc345, with an aberrant RNA pattern possibly due to genome rearrangement, had the same antigenic specificity as Mc323. These 2 strains were genetically very closely related to each other and were more related to porcine than to human rotaviruses. These results provide insights into the evolutionary mechanisms of human rotaviruses.

Animals↗
PubMed1992

Comparisons of rotavirus VP7-typing monoclonal antibodies by competition binding assay.

Three sets of neutralizing monoclonal antibodies (MAbs) used to type the outer capsid protein VP7 of four group A rotavirus serotypes (1 through 4) were compared in competition immunoassays. Reciprocal competition was observed for each of the VP7 type 2-, 3-, and 4-specific MAbs. The VP7 type 1 MAbs exhibited variable competition patterns with other VP7 type 1 MAbs. MAb RV4:3, which has been used to recognize antigenic variants within VP7 type 1 strains, showed reciprocal competition with the four VP7 type 3 MAbs (RV3:1, YO-1E2, 4F8, and 159) using a VP7 type 3 virus (SA11) as antigen. MAb 2C9, also prepared against VP7 type 1, reacted with VP7 type 3 strains and competed with a VP7 type 3 MAb, 159, using RRV as antigen. Use of the different sets of VP7 type-specific MAbs in the enzyme-linked immunosorbent assay permitted the recognition of six antigenic variants within VP7 types 1, 2, and 3 among specimens whose VP7 type could not be determined previously with only one set of typing MAbs. These results demonstrate differences of typing ability among these VP7-specific MAbs and emphasize the need to improve the sensitivity of typing systems by incorporating panels of MAbs reacting with several neutralizing epitopes.

Antibodies, Monoclonal↗