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Biomedical subjects

Y Okuno

Publications and source records attributed to Y Okuno.

At least 325 records · Page 18Linked to original sources
PubMed1983

Retrospective serological studies on dengue epidemics in Osaka and Okinawa.

In Japan, dengue epidemics were recorded once before the end of World War II (1942-1945) on the Main Islands and several times (1893-1955) on the Okinawa Islands. Blood samples were obtained from residents in Osaka and Okinawa, and their antibodies were examined by neutralization tests against dengue and Japanese encephalitis viruses. Of 60 serum samples each from Osaka and Okinawa, 11 and 15 sera, respectively, showed positive titers against one or more dengue serotypes. These results confirm that the epidemics had been very large. Moreover, the results showed that the epidemics had been due to dengue type 1 virus in Osaka and to dengue type 1 and 2 viruses in Okinawa.

Aged↗
PubMed1983

Neutralizing antibody responses to Japanese encephalitis vaccine in children.

Two shots of the current Japanese encephalitis (JE) vaccine were given to children and their immune responses to the Nakayama strain (the vaccine strain) and two wild strains (JaGAr-01 and E-50) of JE virus were examined by neutralizing (N) antibody titrations. Seventy vaccinees had no N antibody to JE virus before the first vaccination and were bled one month after the second vaccination. The N antibody responses to the JaGAr-01 and E-50 strains were found to be similar and to be less than that to the Nakayama strain after the second vaccination: the geometric mean titers (GMT) of N antibodies to the JaGAr-01 and E-50 strains (as logarithms) were 1.87 and 1.75, respectively, while the GMT to the Nakayama strain was 2.89. The seroconversion rates to the Nakayama, JaGAr-01 and E-50 strains were 70/70 (100%), 69/70 (99%) and 68/70 (97%), respectively, after the second vaccination. Twenty-seven of the 70 vacciness were also bled before the second vaccination. Most of them showed a considerably high N antibody response against the Nakayama strain and only one vaccinee failed to show seroconversion after the first vaccination. However, the antibody response to the E-50 strain appeared to be rather low and 9 of 25 vaccinees did not show any seroconversion. Similarly 3 of 25 failed to show any seroconversion against the JaGAr-01 strain. These results indicate that at the initial immunization two shots, at least, of the current JE vaccine are necessary to stimulate effective immune responses to wild strains of JE virus.

Aging↗
PubMed1983

A retrospective serological study of Japanese who contracted dengue fever in Thailand.

Between September and November 1981, some members of a survey team from Japan suffered from a febrile illness diagnosed clinically as dengue fever during their stay in a village in Khon-Kaen Province, in the north-eastern part of Thailand. The morbidity rate in the team was as high as 69% (11/16). Blood samples were taken from 12 of the 16 members of the team in February, 1982 in Japan and the serum specimens were examined for antibodies to dengue (DEN), Japanese encephalitis (JE) and yellow fever (YF) viruses respectively. The results of the tests indicated that all 8 members who had had symptoms had been infected with DEN type 1 virus. No case of inapparent infection with dengue viruses was found. Of these 8 persons, seven had had neutralizing (N) antibody to JE virus before infection, but their clinical manifestations had been similar to those of an individual without N antibody to JE virus and were typical symptoms of dengue fever, such as leukopenia and "saddle-back" fever, without hemorrhagic manifestations, as seen from platelet counts and hematocrit values.

Adult↗
PubMed1983

Serological studies on volunteers inoculated experimentally with a dengue virus strain in 1943.

In 1943, a large dengue epidemic occurred in the Osaka district and several samples of dengue virus were isolated from patients with dengue fever by workers in this Institute. These were inoculated into human volunteers to confirm that they were dengue virus. In the present study, serum samples were collected from the volunteers who had been inoculated with dengue virus and were examined serologically. In the neutralization test, all the sera showed a higher titer against dengue type 1 virus (DEN-1) than against the other three types of dengue virus, indicating that the virus strain isolated in 1943 was DEN-1.

Antibodies, Viral↗
PubMed1982

Serological studies on a case of laboratory dengue infection.

One of the authors (Y.O.), who had previously been immunized with Japanese encephalitis (JE) vaccine, showed symptoms of typical dengue fever 6 days after accidental infection with a newly isolated dengue type 4 virus strain from a patient with dengue hemorrhagic fever (DHF) in Thailand. His sera were examined by hemagglutination inhibition (HI), complement fixation (CF) and neutralization (N) tests. The JE N antibody titers of his sera were high even on the first day of the illness and remained almost constant during the next year. Antibodies that reacted with dengue viruses were detected from a very early stage of the illness by all three serological tests. In addition, his convalescent phase sera showed high titers against all 4 types of dengue virus. These data suggest that the dengue infection caused secondary stimulation of antigens of flavivirus. Sedimentation analysis of antibodies in Y.O.'s serum (day 9) was carried out and IgM antibody that reacted only with dengue type 4 virus and homologous infecting virus was separated. These findings clearly demonstrated that the laboratory infection of Y.O. was primary dengue infection with dengue type 4 virus.

Antibodies, Viral↗
PubMed1982

Neutralization characteristics of dengue viruses isolated in mosquito cell culture and suckling mouse brain from a case of laboratory dengue infection.

One of the authors (Y.O.) of this paper was accidentally infected in the laboratory with dengue type 4 virus, isolated in Thailand in 1978 using the C6/36 clone of Singh's Aedes albopictus cells (SA). Two strains of the virus were isolated from Y.O.'s serum on the first day of illness using SA and suckling mouse brain (SMB). The SA-isolate and the infecting virus were neutralized with high efficiency by Y.O.'s convalescent sera, but the SMB-isolate was neutralized much less efficiently by the same sera. When the hosts of the isolates were exchanged (SA to SMB, and vice versa), the neutralization efficiencies were reversed. For analysis of this phenomenon, prototype dengue type 4 virus exclusively passed in SMB and the same type of virus passaged 10 times in SA were compared with the initial SA- and SMB-isolates in neutralization tests with sera from patients with dengue hemorrhagic fever (DHF) obtained in Thailand. The two strains of the prototype virus and the SA-isolate had similar high reactivities, but the SMB-isolate had low reactivity with sera of the DHF patients.

Aedes↗