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Biomedical subjects

Toshiaki Ihara

Publications and source records attributed to Toshiaki Ihara.

14 recordsLinked to original sources
PubMed2006

Development of a dendritic cell vaccine against measles for patients following hematopoietic cell transplantation.

Most patients who have undergone hematopoietic cell transplantation (HCT) lose specific immunity to measles. However, due to its immunosuppressive potential, it has been recommended that a live attenuated measles vaccination be administered two years following HCT. Measles virus (MV) glycoproteins including hemagglutinin (HA) are expressed on MV-infected dendritic cells (DCs), and they impair efficient antigen presentation between the DC and T cell. We produced a DC-based vaccine against MV by loading DCs with MV-infected autologous DCs. MV in the infected DCs was inactivated using ultraviolet-B. The DC-based vaccine neither expressed HA nor inhibited allogeneic T cell proliferation, while it induced the production of interferon-gamma (IFN-gamma) by autologous CD4 and CD8 naive T cells ex vivo. Importantly, the vaccine derived from patients who had undergone HCT also efficiently induced IFN-gamma producing cells. These findings indicate that our DC-based MV vaccine induces MV-specific immunity even in post-HCT patients without causing immunosuppression.

Adolescent↗
PubMed2006

Difference in production of infectious wild-type measles and vaccine viruses in monocyte-derived dendritic cells.

Macrophages (Mø) and dendritic cells (DC) are thought to be targets of measles virus (MeV) at the early stage of infection. We compared the growth of Edmonston-derived vaccine strains and fresh clinical isolates of MeV in monocytes, monocyte-derived granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced Mø (GM-Mø) and in monocyte-derived DC (Mo-DC). Neither vaccine strains nor fresh isolates thrived in monocytes and GM-Mø and no differences were evident among them. On the other hand, infectious virus production was robust in Mo-DC infected with fresh isolates, but below the limits of detection in those infected with vaccine strains. Although the vaccine strains infected Mo-DC and replicated comparably with the fresh isolates, they accumulated far less matrix (M) protein. This was attributed to a difference in the stability of M protein produced in Mo-DC between the strains. Impaired production of infectious viruses in DC may be one cause of vaccine strain attenuation.

Animals↗
PubMed2006

Rapid detection and typing of influenza A and B by loop-mediated isothermal amplification: comparison with immunochromatography and virus isolation.

A reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) assay was established for the detection of influenza A virus H1 and H3 subtype strains and influenza B virus strains specifically. The total procedure from RNA extraction to virus typing was completed within 3h. In terms of specificity, the representative AH1, AH3 and B strains were detected only by strain-specific primers respectively. No cross-detection was observed. In terms of sensitivity, virus was detected at a minimum concentration of 10 ffu/ml. Eighty-three nasopharyngeal aspirates obtained from children diagnosed clinically with influenza were tested by the RT-LAMP assay, along with commercially available immunochromatography rapid diagnostic tests and by virus isolation. Virus was isolated from 78 samples (94%) and the subtype was determined by the hemagglutination inhibition test. Although it took at least 3 days, the detection sensitivity was the best of the three methods. With two rapid assays, the detection sensitivity of the RT-LAMP assay (85.5%) was higher than that of immunochromatography tests (75.9%). In addition, the RT-LAMP assay can be used to differentiate emerging influenza virus subtypes by selecting appropriate primer sets.

Animals↗
PubMed2006

Efficacy of inactivated trivalent influenza vaccine in alleviating the febrile illness of culture-confirmed influenza in children in the 2000-2001 influenza season.

During the 2000/2001 influenza season in Japan, children ranging in age from 6 months to 13 years with fever exceeding 37.5 degrees C were recruited. Vaccine efficacy was evaluated by comparing the rates of pre-seasonal vaccination between groups stratified by fever severity. Seven hundred and sixty one patients (33.1%), culture positive for influenza were enrolled for analysis. The numbers of patients for A/H1N1 and A/H3N2 were insufficient for statistical analysis. For influenza B the odds ratio for vaccinated children to have a maximum fever exceeding 39.5 degrees C was 0.52 (95% CI, 0.30-0.92) Our findings suggest modest impact of influenza vaccination on limiting severity of disease symptoms.

Adolescent↗
PubMed2006

A comparative study of the incidence of aseptic meningitis in symptomatic natural mumps patients and monovalent mumps vaccine recipients in Japan.

To compare the incidence of aseptic meningitis associated with symptomatic natural mumps infection and in mumps vaccine recipients, we conducted a prospective comparative study. Consecutive samples of 1051 children with mumps were enrolled by 10 pediatricians and 21,465 vaccine recipients by 143 pediatric primary care practitioners, from January 1, 2000 to January 1, 2003. Parents used a daily diary to record symptoms during the period of illness (15 days) or 30-day period following immunization. Mumps infection was confirmed by virus isolation and/or detection of mumps virus genome in salivary and CSF samples. The incidence of aseptic meningitis was 13/1051 (1.24%) in patients with symptomatic natural mumps infection and was estimated to be 0.7-1.1% of overall infection in considering asymptomatic infection, and 10/21,465 (0.05%) in vaccine recipients. Although aseptic meningitis is a clear side effect of the mumps vaccine, the incidence is considerably lower than among those with symptomatic natural infection. Our results provide an informative data for consideration to resume mumps vaccine as a part of routine immunization schedule for Japanese children.

Adolescent↗
PubMed2006

[Varicella].

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Adolescent↗
PubMed2005

Rapid diagnostic method for detection of mumps virus genome by loop-mediated isothermal amplification.

Most mumps patients are clinically diagnosed without any virological examinations, but some diagnosed cases of mumps may be caused by other pathogens or secondary vaccine failure (SVF). To clarify these issues, a sensitive, specific, and rapid diagnostic method is required. We obtained 60 salivary swabs from 34 patients with natural infection during the course of the illness, 10 samples from patients with vaccine-associated parotitis, and 5 samples from patients with SVF. Total RNA was extracted and subjected to reverse transcription-PCR (RT-PCR) and loop-mediated isothermal amplification (LAMP) for genome amplification. We detected mumps virus RNA corresponding to 0.1 PFU by LAMP within 60 min after RNA extraction, with the same sensitivity as RT-nested PCR. Mumps virus was isolated in 30 of 33 samples within day 2, and mumps virus genome was amplified by LAMP in 32 of them. The quantity of virus titer was calculated by monitoring the time to reach the threshold of turbidity. The viral load decreased after day 3 and was lower in patients serologically diagnosed as having SVF with milder illness. Accuracy of LAMP for the detection of mumps virus genome was confirmed; furthermore, it is of benefit for calculating the viral load, which reflects disease pathogenesis.

Animals↗
PubMed2005

[Mumps vaccine].

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Biomarkers↗
PubMed2004

Molecular epidemiology of mumps virus in Japan and proposal of two new genotypes.

We isolated 872 strains of mumps virus from naso-pharyngeal secretions in seven different districts of Japan from January 2000 to July 2001. Among them, 57 strains were geno-typed by nucleotide sequencing in part of the hemagglutinin-neuraminidase (HN) and small hydrophobic (SH) protein regions. Four different genotypes (B, G, K, and L) of mumps virus were co-circulating in Japan and the distribution of genotypes varied in geographically different districts. Two new clusters designated as genotypes K and L had more than 7% nucleotide variation in the SH gene. Among the 57 strains, 11 were classified as B, 35 as G, three as K, and eight as L, which was mainly isolated in Tokyo. We also examined 104 stains isolated in a clinic in Mie prefecture from 1993 to 2003. Genotype B was the indigenous strain and genotype K was introduced in 1994. Genotypes B and K co-circulated in the 1990s and were replaced by genotype G in 2000. There was no significant change in neutralizing test antibody titers against genotypes B, G, K, and L using seven post-vaccination sera with Hoshino strain (genotype B) and these four genotypes had a different antigenicity from genotype A. We should continue to watch on mumps virus molecular epidemiology.

Amino Acid Sequence↗
PubMed2004

Enterovirus-related type 1 diabetes mellitus and antibodies to glutamic acid decarboxylase in Japan.

OBJECTIVES: In order to clarify the relationship between enteroviruses and type 1 diabetes mellitus in Japan we investigated enteroviral RNA in serum from children with type 1 diabetes mellitus. METHODS: We investigated enteroviral RNA in serum from children with type 1 diabetes mellitus by using highly sensitive RT-PCR. Additionally the sequences and viral loads were determined and compared with anti-coxsackie virus antibodies and anti-glutamic acid decarboxylase (GAD) antibodies. RESULTS: RT-PCR for enterovirus was positive in 23 (37.7%) from 61 samples. The positivity had no disparity of age, but decreased by aging after the occurrence of type 1 diabetes mellitus. The sequences of the positives were similar as those of coxsackie B4. The viral loads revealed that there was no positive patient with high titers of anti-GAD antibodies. CONCLUSION: In Japan there is some correlation with type 1 diabetes mellitus and enterovirus. The pathophysiology of type 1 diabetes mellitus seems to consist of a direct destruction by persistent coxsackie virus and the autoimmune mechanism through autoantibodies against beta-cells.

Adolescent↗
PubMed2002

Measles outbreak among non-immunized children in a Japanese hospital.

We experienced an outbreak of measles in which our hospital played an unfortunate role as a vector for the transmission of the disease. Most patients had never been vaccinated and an investigation into the reasons for this revealed a need to more widely promote awareness of measles vaccination in Japan.

Adolescent↗
PubMed2002

[Contamination of oyster sea farm with the Norwalk virus: mechanisms and control].

The Norwalk virus(NV) is widely known as a cause of nonbacterial food poisoning, infant diarrhea, and acute gastroenteritis in the winter months between November and March. While it is strongly suspected that NV that is excreted by humans flows into coastal seawaters via rivers and wastewater treatment facilities to contaminate oysters that are grown in farms in the area, light has yet to be shed on the behavior of this virus in the natural environment. We therefore conducted a polymerase chain reaction (PCR) survey of NV levels in the aquatic environment of the oyster bed area of the Shima region in Mie Prefecture, whereupon the NV was detected in marine sediment, oysters, and mule clams even during the summer months, when food poisoning is infrequent. In order to assess their similarity to human-derived strains, the detected viruses and their human-derived counterparts were subjected to genetic analysis, whereupon some of the detected viruses were found to be remarkably similar to those that were previously detected in humans infected with NV. In the interests of examining methods for decontaminating NV-contaminated oysters, we also conducted an assessment on a system of virus decontamination that focuses on seawater temperature and oyster metabolism, using Poliovirus Sabin strain. The decontamination system mentioned above was a closed loop, water circulating system, built on the same principles as those actually in use at oyster farms. Our experiment indicated that at seawater temperatures of both 10 degrees C and 20 degrees C, virus placed into the water tank was rapidly incorporated into the midgut glands of the oysters. Thereafter, when seawater irradiated with UV was circulated, the virus count in the oysters fell from 1/1,000 to 1/10,000 within 6 hours. These results indicated the utility of this system for virus decontamination, suggesting the possibility of significantly alleviating the risk of NV infection in humans by using this system to maintain the seawater temperature within the decontamination tank above a certain temperature, and to perform decontamination with an adequate water flow.

Animals↗