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Biomedical subjects

M Kohara

Publications and source records attributed to M Kohara.

At least 91 records · Page 5Linked to original sources
PubMed1988

A recombinant virus between the Sabin 1 and Sabin 3 vaccine strains of poliovirus as a possible candidate for a new type 3 poliovirus live vaccine strain.

Biological tests including the monkey neurovirulence test performed on recombinants between the virulent Mahoney and attenuated Sabin 1 strains of type 1 poliovirus indicated that the genome region encoding mainly the viral capsid proteins had little correlation with the neurovirulence or attenuation phenotype of the virus. The results suggested that new vaccine strains of type 2 and type 3 polioviruses may be constructed in vitro by replacing the sequence encoding the antigenic determinants in viral capsid proteins of the Sabin 1 genome by the corresponding sequences of the type 2 and type 3 genome, respectively. Accordingly, we constructed recombinants between the Sabin 1 and Sabin 3 strains of poliovirus in which genome sequences of the Sabin 1 strain encoding most or all capsid proteins were replaced by the corresponding genome sequences of the Sabin 3 strain. One of the recombinant viruses thus constructed was fully viable and showed antigenicity and immunogenicity identical to those of type 3 poliovirus. The monkey neurovirulence tests and in vitro phenotypic marker tests (temperature sensitivity of growth, sodium bicarbonate concentration dependency of growth under agar overlay, and size of plaque) were performed on the recombinant virus. The stability of the virus in regard to the temperature sensitivity phenotype was also tested. The results suggested that the recombinant virus is a possible candidate for a new type 3 poliovirus vaccine strain.

Animals↗
PubMed1987

Association of class II antigens of HLA with primary glomerulopathies.

HLA antigens of Japanese patients with primary glomerulopathies were determined, and the frequency of each HLA antigen was compared with that of Japanese normal controls. IgA nephropathy with HLA-DR4, idiopathic membraneous glomerulopathy with DR2, lipoid nephrosis with DRw53 and poststreptococcal glomerulonephritis with DR1 were definitely or probably associated. It was suggested that primary glomerulopathies might all be associated with HLA class II and not class I antigens. Japanese patients with HLA-Bw48 and -DRw8 were less susceptible to primary glomerulopathies.

Chromosome Mapping↗
PubMed1986

An infectious cDNA clone of the poliovirus Sabin strain could be used as a stable repository and inoculum for the oral polio live vaccine.

Viruses were recovered from HeLa S3 cells and African green monkey kidney (AGMK) cells transfected with an infectious cDNA clone of poliovirus vaccine Sabin 1 strain. The viruses recovered from the different DNA-transfected cells were tested for the biological characteristics of temperature sensitivity (rct marker), plaque size, and bicarbonate concentration dependency (d marker). The results revealed that the above properties were similar to those obtained from tests on the Sabin 1 vaccine reference strain. The recovered viruses and the vaccine reference virus were passaged in AGMK cells at an elevated temperature of 37.5 degrees, and the passaged isolates were tested for the rct marker. The virus recovered from AGMK cells had the most stable rct phenotype while the virus from HeLa S3 cells had a similar stability to that of the reference virus, suggesting that the virus from AGMK cells would be more suitable as a vaccine strain than the other two viruses. Furthermore, an infectious cDNA clone of high specific infectivity, constructed by introducing SV40 large T antigen into the plasmid, was used for production of high titers of virus after transfection. The results of in vitro biological tests on the recovered virus suggested that virus produced in the transfected AGMK cells also had the high quality that is desirable in vaccine stocks. Monkey neurovirulence tests performed with these recovered viruses revealed that the recovered viruses were weakly neurovirulent, similar to the vaccine reference virus. The infectious cDNA clone of the poliovirus vaccine strain could therefore be used to generate a possible inoculum of the oral polio live vaccine. Our findings strongly suggest that an infectious cDNA clone of poliovirus RNA may be used to preserve the constancy and quality of the present seed viruses of the Sabin 1 vaccine strain.

Animals↗
PubMed1986

Genetic analysis of the attenuation phenotype of poliovirus type 1.

Seven different recombinant viruses from the virulent Mahoney and the attenuated Sabin parental strains of type 1 poliovirus were constructed in vitro by using infectious cDNA clones. Monkey neurovirulence tests (lesion score, spread value, and incidence of paralysis) using these recombinant viruses revealed that the loci influencing attenuation were spread over several areas of the viral genome, including the 5' noncoding region. In vitro phenotypic marker tests corresponding to temperature sensitivity of growth (rct marker), plaque size, and dependency of growth on bicarbonate concentration (d marker) were performed to identify the genomic loci of these determinants and to investigate their correlation with attenuation. Determinants of temperature sensitivity mapped to many areas of the viral genome and expressed strong but not perfect correlation with attenuation. Recombinant viruses with Sabin-derived capsid proteins showed a small-plaque phenotype, and their growth was strongly dependent on bicarbonate concentration, suggesting that these determinants map to the genomic region encoding the viral capsid proteins. Plaque size and the d marker, however, were found to be poor indicators of attenuation. Moreover, virion surface characteristics such as immunogenicity and antigenicity had little or no correlation with neurovirulence. Nevertheless, viruses carrying Sabin-derived capsid proteins had an apparent tendency to exhibit less neurovirulence in tests on monkeys compared with recombinants carrying Mahoney-derived capsid proteins. Our results suggest that the extent of viral multiplication in the central nervous system of the test animals might be one of the most important factors determining neurovirulence. Moreover, we conclude that the expression of the attenuated phenotype of the Sabin 1 strain of poliovirus is the result of several different biological characteristics. Finally, none of the in vitro phenotypic markers alone can serve as a good indicator of neurovirulence or attenuation.

Animals↗
PubMed1985

Antigenic variation and resistance to neutralization in poliovirus type 1.

Mutations have been identified in variants of poliovirus, type 1 (Mahoney) on the basis of their resistance to neutralization by individual monoclonal antibodies. The phenotypes of these variants were defined in terms of antibody binding; the pattern of epitopes expressed or able to be exploited for neutralization were complex. Single amino acid changes can have distant (in terms of linear sequence) and generalized effects on the antigenic structure of poliovirus and similarly constituted virions.

Amino Acid Sequence↗
PubMed1985

In vitro phenotypic markers of a poliovirus recombinant constructed from infectious cDNA clones of the neurovirulent Mahoney strain and the attenuated Sabin 1 strain.

Infectious cDNA corresponding to the entire genome of the attenuated Sabin strain of type 1 poliovirus has been inserted into EcoRI site of bacterial plasmid pBR325. Two consecutive PstI fragments (nucleotide positions 1814 to 3421) of the infectious cDNA of the Sabin 1 strain were replaced by the corresponding DNA fragments prepared from an infectious DNA clone of the genome of the virulent Mahoney strain of poliovirus type 1. The exchanged segment encodes capsid protein VP1 and part of capsid protein VP3, a region in which a large number of amino acid differences between the attenuated Sabin and the parental, neurovirulent Mahoney strain cluster. The recombinant virus was obtained by DNA transfection of HeLa S3 cells, and several in vitro phenotypes of the virus were compared with those of the parental viruses. The recombinant virus was recognized by a neutralizing monoclonal antibody specific to the Mahoney strain. Growth of the Sabin strain of poliovirus has been shown to be quite dependent upon the bicarbonate concentration (d marker). The growth of the recombinant virus, however, was not highly dependent upon the concentration of bicarbonate in cell culture media, and thus resembled that of the Mahoney strain. On the other hand, the temperature-sensitive multiplication (rct marker) and the small-plaque morphology of the recombinant virus corresponded to the phenotype of the Sabin 1 strain. The in vitro recombination of infectious cDNA clones of genomic RNA and subsequent analysis of the growth properties of the recombinant virus have allowed us to correlate specific mutations in the genome of an RNA virus with certain biological characteristics of that virus.

Bicarbonates↗
PubMed1985

The strong association of HLA-DR4 with spherical mesangial dense deposits in IgA nephropathy.

41 Japanese patients with primary IgA nephropathy (IgA GN) were determined for HLA-A, -B, -C and -DR antigens. The frequency of HLA-DR4 increased slightly in total patients compared with 63 normal control persons, but this increase was not statistically significant. However, 24 patients with spherical mesangial dense deposits (SMDD) in electron micrograph out of 41 patients with IgA GN were found to have markedly increased incidence of HLA-DR4 (chi 2 = 11.52, Relative risk = 6.45, Corrected p less than 0.03). In contrast to this finding, 17 patients without SMDD had no association with any particular HLA antigens. These results suggest that IgA GN might be subdivided by the association of HLA and electron microscopic findings into at least 2 types.

Adolescent↗
PubMed1984

Complete nucleotide sequences of all three poliovirus serotype genomes. Implication for genetic relationship, gene function and antigenic determinants.

The complete nucleotide sequences of the genomes of the type 2 ( P712 , Ch, 2ab ) and type 3 (Leon 12a1b ) poliovirus vaccine strains were determined. Comparison of the sequences with the previously established genome sequence of type 1 (LS-c, 2ab ) poliovirus vaccine strain revealed that 71% of the nucleotides in the genome RNAs were common, that the 5' and 3' termini of the genomes were highly homologous, and that more than 80% of the nucleotide differences in the coding region occurred in the third letter position of in-phase codons, resulting in a low frequency of amino acid difference. These results strongly suggested that the serotypes of poliovirus derived from a common prototype. A comparison of the amino acid sequences predicted from the genome sequences showed highest variation in the capsid protein region, whereas non-structural proteins are highly conserved. Initiation of polyprotein synthesis occurs in all three strains more than 740 nucleotides downstream from the 5' end. An analysis of the non-coding region suggests that small peptides that could potentially originate from this region are conserved. The amino acid sequences immediately surrounding the cleavage signals, however, show a higher than average degree of variation. The analysis of the amino acid sequences of the capsid protein VP1 of all serotypes has led to the prediction of potential antigenic sites on the virion involved in neutralization.

Amino Acid Sequence↗
PubMed1984

Cloned infectious complementary DNA of the poliovirus Sabin 1 genome: biochemical and biological properties of the recovered virus.

A complete cDNA copy of the genome of the attenuated type 1 poliovirus vaccine (Sabin 1) strain was constructed and inserted into the EcoRI site of the plasmid pBR325. When cultured mammalian cells were transfected with this recombinant plasmid, 20 to 50 poliovirus plaques per 10 micrograms plasmid DNA were observed. Fingerprints of the RNA of the recovered virus showed no changes when compared with those of the parental virus genome, an observation indicating that the primary structure of the cloned cDNA is a reflection of authentic poliovirus RNA. The recovered virus had the same properties as those of the Sabin 1 strain in regard to antigenicity, sensitivity to temperature, and dependency on bicarbonate concentration. These results suggest that the virus obtained by DNA transfection is indistinguishable from the Sabin 1 strain. The recombinant plasmid could therefore be used as a stable repository of the virus and as inoculum for the oral polio live vaccine.

Animals↗
PubMed1984

Expression of poliovirus complementary DNA coding for viral antigenic determinants in Escherichia coli.

DNA sequences coding for the immunogenic capsid protein VP1 and/or VP3 of poliovirus strain LSc-2ab (Sabin 1) were prepared by digesting the cloned complementary DNA with restriction endonuclease PstI. The DNA fragments were inserted into the unique PstI site of Escherichia coli plasmid vectors pBR322, pKT 280 and/or pKT 287 that lay in the region expressed under control of the penicillinase promoter system. In the expression vectors, poliovirus sequences were designed to be read in phase and therefore to be expressed as fusion proteins with the bacterial peptides. In addition, the Escherichia coli tryptophan operon promoter-operator system was inserted upstream of the penicillinase system to obtain stronger expression of the poliovirus sequences. Escherichia coli transformed with these plasmids appeared to produce the antigenic polypeptides, which were detected by immunoprecipitation with antibodies to capsid proteins VP1 and/or VP3 followed by SDS-polyacrylamide gel electrophoresis.

Amino Acid Sequence↗
PubMed1983

Morphological study of age-related changes in mouse lens.

Age-related changes in the lenses of ddy strain mice, ranging from 4 to 24 months old, were studied histologically. The early change of aging lens was noted as a slight extension of fiber cells into the posterior capsule in the area behind the nuclear bow around 6 months of age. Those cell extensions formed villous projections reaching up to one half of the total capsule by 18 months of age. Another notable change was a decreasing cell population of the lens epithelium and the appearance of their nuclear inclusions. The latter contained rough endoplasmic reticulum, free ribosomes and filamentous matrix at the early stage and a mass of filamentous material at the later stage. This change was initiated by 12 months of age, and became profound with the increase of age. Moreover, the bow nuclei became markedly displaced posteriorly after 14 months of age. At about 18 months of age, when the pathological changes in both epithelial and bow regions became severe, the superficial cells in the posterior cortex showed swelling and atrophy, which soon led to the lens opacity due to accumulation of cell debris and fluid. These histopathological changes associated with aging appear to correspond to the incipient form of posterior subcapsular cataract which is detectable by clinical examinations.

Aging↗