Biomedical subjects
Publications and source records attributed to S Hotta.
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A latex agglutination test was evaluated as a method for detection and titration of antiplague antibodies. Slide and microtiter techniques using polystyrene latex particles coated with specific fraction-I-antigen of Yersinia pestis were found to be comparable in specificity and sensitivity to serological tests commonly used in laboratory practice. The latex agglutination titers correlated well with those measured by the World Health Organization standard method of indirect hemagglutination, although there was a tendency for the former to be a little lower than the latter. With further study, the latex agglutination test may have application in the seroinvestigation of plague infection in rodents.
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Twenty kinds of disinfectants were examined for ability to inactivate variola virus. Cytopathic effect and plaque formation on monolayer cultures of an established monkey kidney cell line were used as indicators of virus inactivation. A micromethod using microplate cultures, and not requiring a CO2 incubator, was adopted. The procedures were straightforward, showing good reproducibility. Among the compounds tested, several were found to be superior because of the minimum concentrations required for complete inactivation of virus. The purified viruses were shown to be more sensitive to the compounds than were the crude samples. The virus inactivation kinetics curves were determined by plaque counting. The usefulness of this method for quantitative analysis of disinfecting effect is suggested.
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Dengue virus plaque formation on BHK-21 cell microplate cultures was described. The clear plaques were visible usually 5 days after incubation in a CO-2 incubator at 37 degrees. The cells cultured in a 3-oz bottle were sufficient to prepare two microculture plates which were usually ready for use after 1-2 days of cultivation in the CO-2 incubator at 37 degrees. The overall procedures were easy and of economic advantage.
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The indirect haemagglutination (IHA) test has been widely applied in the detection of antiplague antibodies in rodent sera. In the present study, acetone treatment of the test serum was tried in order to improve the specificity of the reaction. It was shown that the IHA titres of acetone-treated sera correlated well with those of untreated sera measured by the standard method recommended by WHO. Essentially the same results were obtained with sera from experimentally immunized rodents and from captured wild rats. In addition to acetone treatment, the sera were treated with 2-mercaptoethanol (ME). The results obtained indicated that the antiplague IHA antibodies produced early after the inoculation of plague bacilli were ME-sensitive, whereas those detected in the later stages or after a second inoculation were ME-resistant. The data suggest that acetone treatment of sera could be useful for the screening of antiplague antibodies, and that treatment with ME is helpful in assessing the time of past plague infections. The present survey has also shown that the positive rates of antiplague antibodies in wild rats trapped in Kobe, one of the largest sea ports in Japan, have so far been very low.
Chikungunya (CHIK) virus, harvested from infected BHK-21 cell cultures and highly purified by a method combining zinc acetate precipitation, Sephadex-Sepharose column chromatography, and sucrose density gradient centrifugation, was subjected to ultraviolet (UV) irradiation and treatment with formalin. Inactivation of the virus by UV light was apparently a first-order reaction. The virus treated with 0.05% formalin at 4 degrees C was inactivated completely after 7 weeks, but when treated with 0.025% formalin retained its plaque infectivity at least 17 weeks. Both UV- and formalin-inactivated viruses induced production of anti-CHIK neutralizing antibodies in Japanese monkeys with no preimmune antibodies. Judging by the titres of antibodies produced, the immunogenic effect of the UV-irradiated virus was superior to that of the formalin-treated virus.
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