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Biomedical subjects

I Takashima

Publications and source records attributed to I Takashima.

At least 109 records · Page 6Linked to original sources
PubMed1988

Ecological studies of Japanese encephalitis virus in Hokkaido: interepidemic outbreaks of swine abortion and evidence for the virus to overwinter locally.

Outbreaks of abortion and stillbirth caused by Japanese encephalitis virus were observed in swine populations in Hokkaido in 1984 and 1985. Two strains of Japanese encephalitis virus were isolated from aborted fetuses in different outbreaks, and the antigenic types of the strains found to be different from Nakayama and JaGAr-01. The outbreak of 1985 was in early June, the interepidemic period of Japanese encephalitis in northern temperate zones. A seroepidemiological survey carried out from 1984 to 1986 in 14 districts showed high rates of Japanese encephalitis antibody in swine sera in two districts. A more detailed 3-year survey showed that pig farms positive for Japanese encephalitis antibody were detected at the same sites in Hiroshima near Sapporo as negative farms. These data suggest that Japanese encephalitis virus is maintained in a distinct endemic focus and has the capacity to overwinter locally in Hokkaido.

Abortion, Veterinary↗
PubMed1986

Epidemiological studies of hemorrhagic fever with renal syndrome (HFRS) related virus infection among urban rats in Hokkaido, Japan.

Seroepidemiological studies of hemorrhagic fever with renal syndrome (HFRS) virus infection were carried out among urban rats (Rattus norvegicus and Rattus rattus) and small field rodents in Hokkaido, Japan. An urban rat colony that was seropositive to SR-11 strain of HFRS virus (laboratory rat origin) was demonstrated in February 1983 at a dumping ground area of Kami-iso Town near Hakodate port. An HFRS-related virus, named KI-262 strain, was isolated from the lung tissue of a seropositive rat using Vero-E6 cell culture. Antigenicity of the isolate was closely related to Hantaan 76-118 and SR-11 strains by the indirect immunofluorescent antibody (IFA) test. No seropositive rat was found among the 861 rats captured in 38 other regions. It is unclear whether or not the infected rats in the positive area were introduced from abroad, though the area is located near Hakodate International Port. Furthermore, higher positive rates of urban rats in the Kami-iso area were observed in the spring and winter than in the summer and fall. Significantly high proportion of positive cases was observed among adult rats (six months or older) than among younger animals. The seasonal and age distribution of positive cases suggested that the virus was not readily transmitted from one infected rat to another. One seropositive case of a small field mouse (Clethrionomys rufocanus bedfordiae) was detected around the Kami-iso area.

Age Factors↗
PubMed1986

Monoclonal antibodies against Chlamydia psittaci.

Five monoclonal antibodies were prepared against Chlamydia (C.) psittaci strain Pigeon-1041 isolated from a feral pigeon in Sapporo. Reactions of these antibodies to chlamydiae were examined using five strains of C. psittaci and two strains of C. trachomatis in an enzyme-linked immunosorbent assay, microimmunofluorescent test and complement fixation test. The antibodies were divided into two groups: three genus-specific (A2, D2, and I21) and two strain-specific (F2 and H9) antibodies. The antigenic determinant site of A2 was KIO4 sensitive, but those of D2, F2, and H9 were not affected greatly by KIO4 treatment. Nine C. psittaci strains from feral pigeons and 16 strains from budgerigars were classified into three groups and four groups, respectively, by reaction patterns against the monoclonal antibodies.

Animals↗
PubMed1985

Cell fusion by haemorrhagic fever with renal syndrome (HFRS) viruses and its application for titration of virus infectivity and neutralizing antibody.

Haemorrhagic fever with renal syndrome viruses, are members of the family Bunyaviridae. They cause cell to cell fusion from within under acidic conditions. This phenomenon was found to occur under a pH range of between 4.9 to 6.3 for all the viruses examined. The pH range which causes cell fusion was similar to that reported for the La Crosse virus of the Bunyaviridae, hence indicating that this property is a common biological characteristic among this family of viruses. Titration of virus infectivity and neutralizing antibody was done by counting the number of fused cell foci produced in infected Vero cell monolayers after low pH treatment. This method was simpler and more rapid than the ordinary plaque formation method or that of counting infected cell foci by IFA or immunoenzyme assay. In addition, this method may also be applicable in the detection of other enveloped viruses which do not cause a typical cytopathic effect.

Animals↗
PubMed1985

Getah virus in several species of mosquitoes.

Vector competence of Aedes (Ae.) vexans nipponii (nip.) and Culex (Cx) tritaeniorhynchus for Getah virus was compared after incubation at 28 degrees C and 20 degrees C. Marked differences existed between Ae. vexans nip. strains Sapporo and Cx tritaeniorhynchus strain Kyoto in infection and transmission rates following ingestion of blood meals containing several concentrations of Getah virus. Simultaneous comparison of infectivity also revealed that infection rates of Ae. vexans nip. strains Sapporo (74%) and Shizunai (68%) were higher than those of Cx tritaeniorhynchus strain Kyoto (44%). No significant differences were seen in infection rates between three strains of Cx tritaeniorhynchus or between two strains of Ae. vexans nip. Getah virus propagated and was transmitted in Ae. vexans nip. as rapidly at 20 degrees C as at 28 degrees C. Following seven days' incubation both at 20 degrees C and 28 degrees C, Ae. vexans nip. was capable of transmitting the virus. 14 days' incubation at 20 degrees C were needed for Cx tritaeniorhynchus to acquire the same capability. Ae. japonicus, Ae. aegypti, Ae. albopictus, Cx pipens pallens, Armigeres subalbatus and Tripteroides bambusa were also susceptible to Getah virus infection.

Aedes↗
PubMed1985

Epidemiological study of hemorrhagic fever with renal syndrome related virus infection among urban rats in two islands in Tokyo Bay, Japan.

A seroepidemiological survey of hemorrhagic fever with renal syndrome (HFRS) virus infection in 403 urban rats (Rattus norvegicus) captured on two different islands in Tokyo Bay was carried out using the indirect immunofluorescent antibody (IFA) test with the SR-11 strain of HFRS virus. Antibody positive sera were detected in 99 out of 355 (27.9%) rats from the island with reclaimed ground area, but none were detected in 48 rats from the other islands. IFA titers of the positive sera varied from 16 to 4,096 (mostly 128) with a peak at 1 : 128, and antibody positive ratios were significantly higher in the small rats (less than 50 g, probably of younger age) than in the large ones. A causative agent antigenically related to HFRS virus was isolated from lung tissue of seropositive rat using Vero-E6 cells. These results revealed the existence of HFRS related virus among urban rats in the coast of Tokyo Bay, Japan.

Animals↗
PubMed1984

Biotin-labeled antigen sandwich enzyme-linked immunosorbent assay (BLA-S-ELISA) for the detection of Japanese encephalitis antibody in human and a variety of animal sera.

A biotin-labeled antigen (BLA) was adapted to a sandwich enzyme-linked immunosorbent assay (S-ELISA) for detection of Japanese encephalitis (JE) antibody in a variety of animal sera. JE antigen was fixed on the wells of a microplate and became bound to the specific antibody which could react with a peroxidase-labeled avidin conjugate and azino-di-(3-ethylbenzthiazolin sulfonic acid) (ABTS) as a substrate. The BLA-S-ELISA could simultaneously detect JE antibody in all hemagglutination inhibition (HI) positive sera from man, swine, monkey, horse, cattle, rabbit, rat, mouse and pigeon by using the same reagents under the same test conditions. The antibody titers obtained by BLA-S-ELISA in human and swine sera corresponded well with HI antibody titers. The sensitivity of BLA-S-ELISA appeared to be higher for IgM antibody than for IgG antibody. Since the non-specific reaction was extremely low in BLA-S-ELISA, the cut-off titer for the assay could be set as low as 1:2.5 of serum dilution for positive antibody.

Animals↗
PubMed1984

Biotin-labeled protein-A enzyme-linked immunosorbent assay for the detection of Japanese encephalitis antibody in sera from humans, swine and several animal species.

Biotin-labeled protein-A was incorporated into enzyme-linked immunosorbent assay (ELISA) for seroepidemiological surveys of Japanese encephalitis (JE) virus infection in several vertebrates. The ELISA could detect the JE antibody in sera from man, rhesus monkey, swine, horse, dog, rabbit and mouse by the same reagent, but not in sera from cattle and pigeon. The titers of ELISA antibody were almost the same as those of 2-ME resistant HI antibody. Since non-specific reaction in ELISA was very low in the sera of swine and humans, the cut-off titer for the assay could be set at 1:5 for positive antibody.

Animals↗
PubMed1984

Antigenic analysis of flaviviruses with monoclonal antibodies against Negishi virus.

Twelve monoclonal antibodies against Negishi virus were obtained and characterized by hemagglutination inhibition (HI) and neutralization (NT) tests using five flaviviruses isolated in the pan-Pacific region. The reaction pattern of the antibodies showed that Negishi virus was most closely related to Langat virus, followed by 3-Arch, JE and Apoi viruses in that order. Hemagglutinating (HA) antigen of the virus had distinct HI relating sites which were Negishi virus specific, tick borne encephalitis (TBE) virus complex specific and flavivirus cross-reactive. Monoclonal anti-Negishi antibodies cross-reactive to Japanese encephalitis (JE) virus in the HI test had neutralizing activity to JE virus but no activity to homologous Negishi virus.

Animals↗
PubMed1984

Preparation of complement fixation antigen of Chlamydia psittaci grown in tissue culture by treatment with beta-propiolactone.

A new method of preparing a chlamydial complement fixation (CF) antigen by treatment with beta-propiolactone (BPL) is presented. Chlamydia psittaci strains Pigeon-1041 and Budgerigar-No. 1, and Chlamydia trachomatis strain L2/434/BU, propagated in L-929 cell monolayers, were inactivated with BPL. This BPL-treated antigen was useful for detecting CF antibodies in both human and pigeon sera, and it did not cause false-positive reactions, as are sometimes observed between some human sera and phenol-treated antigen derived from eggs. When this CF antigen was treated with potassium periodate and tested for reactivity with mouse immune ascitic fluid, it was found that the antigen contained type- or strain specificity as well as genus specificity. Immunization with the BPL-treated antigen elicited type- or strain-specific neutralizing antibody.

Animals↗