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Tetsuo Nakayama

Publications and source records attributed to Tetsuo Nakayama.

At least 19 recordsLinked to original sources
PubMed2006

Simple differentiation method of mumps Hoshino vaccine strain from wild strains by reverse transcription loop-mediated isothermal amplification (RT-LAMP).

Mumps virus is still circulating and annual mumps outbreaks occur with fluctuating magnitudes in Japan. Aseptic meningitis has been reported after vaccination and it would be of importance to determine whether this was related to the vaccination. The objective of this study was to develop a sensitive, specific and rapid diagnostic method for the differentiation of the Hoshino vaccine strain from circulating wild types. We developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) method of the hemagglutinin neuraminidase (HN) region for the detection of mumps virus genome from clinical samples. The typical ladder pattern disappeared after the LAMP products of the Hoshino vaccine strain were digested with ScaI, but those of wild types were not cut by ScaI. We obtained 19 cerebro spinal fluids (CSF) from the patients with aseptic meningitis and 17 salivary swab samples from the patients with acute parotitis after mumps vaccination, in which one case was complicated with orchitis. Mumps virus genome was detected in 18 CSF samples and in all NPS by RT-LAMP. The Hoshino vaccine strain was identified in 16 out of 18 CSF RT-LAMP positives and in 11 out of 17 NPS samples and the remaining samples were identified as wild types. RT-LAMP followed by ScaI digestion is a sensitive, simple and rapid differential method and useful for laboratory surveillance for vaccine-adverse events.

Base Sequence↗
PubMed2006

Vaccine adverse events reported in post-marketing study of the Kitasato Institute from 1994 to 2004.

General physicians, pediatricians and parents realize that serious adverse events occur with an extremely rare incidence, but have no information on the incidences of vaccine-associated adverse events. A proper understanding of vaccine adverse events would be helpful in promoting an immunization strategy. Causal association can rarely be determined in adverse events through laboratory examinations. We examined the cases reported in the post-marketing surveillance of the Kitasato Institute, categorizing them into two groups: allergic reactions and severe systemic illnesses. Anaphylactic patients with gelatin allergy after immunization with live measles, rubella and mumps monovalent vaccines have been reported since 1993, but the number of reported cases with anaphylaxis dramatically decreased after 1999 when gelatin was removed from all brands of DPT. The incidence of anaphylactic reaction was estimated to be 0.63 per million for Japanese encephalitis virus (JEV) vaccine, 0.95 for DPT and 0.68 for Influenza vaccine, but the causative component has not yet been specified. Among 67.2 million immunization practices, 6 cases with encephalitis or encephalopathy, 7 with acute disseminated encephalomyelitis (ADEM), 10 with Guillain-Barré syndrome and 12 with idiopathic thrombocytopenic purpura (ITP) were reported. The wild-type measles virus genome was detected in a patient with encephalitis and in two of four bone marrow aspirates obtained from ITP after measles vaccination. Enterovirus infection was identified in two patients after mumps vaccination (one each with encephalitis and ADEM), one patient with encephalitis after immunization with JEV vaccine, and one with aseptic meningitis after immunization with influenza vaccine. The total estimated incidence of serious neurological illness after vaccination was 0.1-0.2 per million immunization practices. We found that enterovirus or wild-type measles virus infection was coincidentally associated with vaccination in several cases suspected of being vaccine adverse events.

Data Collection↗
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

Development of a new method for diagnosis of rubella virus infection by reverse transcription-loop-mediated isothermal amplification.

We developed a useful method for the detection of rubella virus genome RNA by reverse transcription loop-mediated isothermal amplification (RT-LAMP) and compared the sensitivity of RT-LAMP with that of other virological tests: reverse transcription-PCR (RT-PCR) and virus isolation. The rubella virus genome was amplified by RT-LAMP from clinical isolates obtained between 1987 and 2004 with similar sensitivities to the Takahashi vaccine strain. The detection limit of RT-LAMP was compared with that of RT-PCR using the Takahashi vaccine strain. We detected rubella virus genome material corresponding to 30 PFU/ml in a culture fluid sample by RT-LAMP within 60 min after the extraction of RNA with equal sensitivity to RT-nested PCR. The positive result rates of RT-LAMP, RT-PCR, and virus isolation were also compared using throat swabs obtained from patients who were clinically diagnosed with acute rubella virus infection in 2004 in Tochigi, Japan. Among nine patients with clinical rubella, the positive result rates were three/nine (33.3%) for virus isolation, six/nine (66.7%) for RT-PCR, and seven/nine (77.8%) for RT-LAMP. Consequently, RT-LAMP for rubella virus would be expected to be a reliable rapid diagnostic tool in the clinical setting.

Genome, Viral↗
PubMed2005

Passage in Vero cells alters the characteristics of measles AIK-C vaccine strain.

Objective of this study is to evaluate the feasibility of measles vaccine production in Vero cell culture. We constructed the full-length cDNA, pIC-MVAIK-F278Leu (small plaque-type) and pIC-MVAIK-F278Phe (large plaque-type) from the AIK-C measles vaccine strain attenuated from the Edmonston wild-type. MVAIK-S/B2 was rescued from pIC-MVAIK-F278Leu after two passages in B95a cells and MVAIK-SL/B2V1 was obtained through large plaque cloning in Vero cells. MVAIK-SL/B2V8 was obtained after eight passages in Vero cells. It produced large plaques in Vero cells, grew well at 39 degrees C, and thus the characteristics of the AIK-C vaccine strain were lost. Thirteen amino acid changes were observed; one in the N, two in the P, one in the C, three in the F, one in the H, and five in the L protein regions. Twelve of these changes excluding one in the L gene were back mutated to the Edmonston strain. Change from Leu to Phe at position 278 of the F protein was an early event during adaptation to Vero cells and the P gene was back-mutated to the Edmonston wild-type. As for the control, MVAIK-L/B9 strain was obtained after passages in B95a cells from pIC-MVAIK-F278Phe (large plaque-type). It maintained the same temperature sensitivity as the AIK-C vaccine strain and only four amino acid changes, one in the N and three in the L protein region, were observed without any mutations in the P, C, M, F, and H genes. The passage of the measles vaccine AIK-C strain in Vero cells lost the characteristics of small plaque inducibility and temperature sensitivity (ts) phenotype.

Amino Acid Sequence↗
PubMed2005

The phosphoprotein of attenuated measles AIK-C vaccine strain contributes to its temperature-sensitive phenotype.

Measles AIK-C vaccine strain exhibits temperature-sensitivity (ts). To identify the structural proteins, which contribute to the ts property of AIK-C virus, reverse genetics was used. MV-minigenome RNA was replicated at 32.5, 37, and 39 degrees C when the plasmids expressing N, P, and L proteins of the Edmonston strain (the parental strain of AIK-C) were used, whereas the minigenome RNA replicated only at 32.5 degrees C but did not at 37 degrees C and higher temperature when N, P, and L protein expression plasmids of the AIK-C strain were used. A series of minigenome experiments revealed that the amino acid substitution of leucine at position 439 of the P protein by proline (P439-Pro) contributes to the ts phenotype of AIK-C. Four recombinant viruses having various P genes were rescued from the modified AIK-C genome cDNA and ts-characteristics were compared in Vero cells by plaque formation assay. The results showed that the P439-Pro of AIK-C virus played a key role in the ts phenotype, but the other substitutions in the P gene might have an accessory function in the expression of the phenotype.

Amino Acid Substitution↗
PubMed2005

A phylogenetic study of human respiratory syncytial viruses group A and B strains isolated in two cities in Japan from 1980-2002.

The circulation pattern and genetic evolution of respiratory syncytial virus (RSV) in Japan were examined based on 109 RSV field strains isolated over 20 seasons (1980-2002) in two cities, Sapporo and Tokyo. The second hypervariable region of the large glycoprotein (G) gene was amplified by RT-PCR and the products sequenced directly. The nucleotide sequences were compared to those representatives of RSV genotypes identified previously. Japanese group A and B isolates clustered into five and four genotypes defined previously, respectively. Another one group A and one group B genotypes, which could not be assigned to previous genotypes, were also identified. Although different genotypes usually co-circulated in each season, the isolates in proximate seasons from two communities were usually located in the same branches. Moreover, the strains with genotypes defined previously were usually isolated at the same time as each reference strain of Western countries. Several mutant group B strains with 1-20 longer amino acid G proteins were newly identified in Sapporo. These findings suggest that Japanese RSV strains underwent geographical and also temporal clustering while participating in RSV genetic evolution in a global setting. In addition, Japanese strains, especially group B, might have evolved individually in each community, sometimes changing the length of the G protein.

Amino Acid Sequence↗
PubMed2005

A simple method for the detection of measles virus genome by loop-mediated isothermal amplification (LAMP).

Approximately 20,000-30,000 measles patients were reported in a surveillance of infectious diseases because of low vaccine coverage of 80% in Japan. Among them, some were thought to be secondary vaccine failure (SVF) with generally mild or non-typical measles illness and sometimes became a source of further transmission. We have developed a new, sensitive, and rapid method to detect the measles virus genome by reverse transcription loop-mediated isothermal amplification (RT-LAMP). We examined 50 nasopharyngeal secretion (NPS) samples that were obtained during the 1999 outbreak and stored at -70 degrees C and fresh NPS, lymphocytes and sera from 11 patients in 2003. Total RNA was extracted from the samples and subjected to reverse transcription-polymerase chain reaction (RT-PCR) and RT-LAMP. We detected the genomic RNA corresponding to at least 0.01-0.04 TCID50, 30-100 copies in samples by RT-LAMP within 60 min after extraction of RNA, and all four genotypes isolated in Japan were equally amplified. Specific DNA amplification was monitored spectrophotometrically by real time turbidimeter and the quantity of RNA was calculated. Measles virus genome was detected in 44 of 50 stored NPS by RT-PCR and in 49 by RT-LAMP. The vaccine strain was discriminated from wild strains after sequencing the LAMP products. RT-LAMP is a useful rapid diagnostic method for the detection of measles virus without any special apparatus, showing higher sensitivity than RT-PCR, and expected to be applied for hospital-based infection control and for laboratory-based measles surveillance.

Base Sequence↗
PubMed2005

Detection of respiratory syncytial virus genome by subgroups-A, B specific reverse transcription loop-mediated isothermal amplification (RT-LAMP).

Annual seasonal outbreaks of respiratory syncytial virus (RSV) infection occur every winter. Most patients are diagnosed clinically by a rapid detection kit for RSV protein(s) from nasopharyngeal secretion (NPS), but some problems have been reported on the specificity and sensitivity of such rapid detection kits. To ratify these issues, a sensitive, specific, simple, and rapid molecular based diagnostic method is expected to be introduced and we have developed a method to detect the RSV genome of subgroups A and B independently by reverse transcription loop-mediated isothermal amplification (RT-LAMP). We detected the genomic RNA corresponding approximately to 0.1 TCID 50 in the sample by RT-LAMP for both RSV subgroups under isothermal condition within 60 min after extraction of RNA. Specific DNA amplification was monitored by a real-time turbidimeter and the quantity of RNA was calculated. The RSV genome was detected in 47 of 50 NPS by RT-LAMP, and in 42 by nested RT-PCR, whereas virus isolation was positive for 29 and enzyme-linked immunoassay (EIA) for 34. RSV subgroup A was detected in 25 by RSV RT-LAMP A, RSV subgroup B in 23 by RSV RT-LAMP B, and dual infection with RSV subgroups A and B was identified in one case. They were confirmed with digestion with a specific restriction enzyme, Bgl II. The results showed the potential clinical feasibility of RT-LAMP as a useful diagnostic tool for the detection of RSV with high sensitivity similar to nested RT-PCR.

Genome, Viral↗
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↗
PubMed2004

Poor immune responses to influenza vaccination in infants.

Twenty-two and 37 infants and young children received two doses of influenza HA vaccine before the 2001-2002 influenza season and before the 2002-2003 season, respectively. Two or three serial specimens were obtained, before and 1 month after the first vaccination as well as 1 month after the second vaccination. Infants showed a significantly poor HI antibody rise and lymphocyte response compared with young children aged > or =12 months. Time kinetics of the lymphoproliferative responses to influenza antigen among young children varied whereas their activities in infants were typically negative before immunization and increased after vaccination. Infants responded poorly to HA influenza vaccine compared with young children.

Adult↗
PubMed2004

Recombinant measles AIK-C strain expressing current wild-type hemagglutinin protein.

We constructed a recombinant measles virus cDNA, pIC-MVAIK-H/87-K, in which the hemagglutinin (H) gene of the AIK-C vaccine strain was replaced by the wild-type (MVi/Tokyo.JPN/87-K: genotype D3) H gene and the remaining genes were the same as the AIK-C vaccine strain. To investigate the feasibility of the recombinant vaccine strain expressing wild-type H protein instead of the AIK-C H protein, we constructed two recombinant measles cDNA, having Leu (small plaque-type) and Phe (large plaque-type) at position 278 of the F protein. Infectious chimeric virus strains, MVAIK-H/87-K/S (small plaque-type) and MVAIK-H/87-K/L (large plaque-type), were recovered, which were designed to induce small (S) and large (L) plaques in Vero cells. The MVAIK-H/87-K/S and MVAIK-H/87-K/L did not grow at 39-40 degrees C, similar to the original AIK-C strain, and retained the temperature sensitivity (ts) characteristics. They did not induce cytopathic effect (CPE) in Vero cells but produced CPE in B95a cells, similar to the current wild-type measles MVi/Tokyo.JPN/87-K. From the results of Western blotting, the mobility of the H protein of MVAIK-H/87-K/S and MVAIK-H/87-K/L was similar to that of MVi/Tokyo.JPN/87-K. Hyper-immune sera raised by MVAIK-H/87-K/S neutralized all types of current wild strains. Thus, the chimeric measles virus expressing the current wild H protein demonstrated wild-type H properties with ts characteristics of the vaccine strain, indicating that the construction strategy of recombinant measles virus can cope with the hyper-mutated measles virus.

Animals↗
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

Bone scintigraphic and CT evaluation of chondrosarcoma of the rib: correlation with histological grade in 6 cases.

OBJECTIVE: The objective of this study is to assess the value of CT and bone scintigraphic findings for grading of rib chondrosarcoma. METHODS: Included in this study were six cases of histologically proven chondrosarcoma of the rib, in which bone scintigraphy and/or CT was performed. Correlation of histologic grade (I-III), tumor size on CT, CT grading (modified Brown's system), the pattern (nodular or peripheral, presence or absence of extended uptake pattern) and the intensity (Simon and Kirchner's grade, 0-4) of scintigraphic uptake were assessed. RESULTS: CT grade was III, except for one case of dedifferentiated chondrosarcoma. Scintigraphic grade was 3 or 4 in all the cases. CONCLUSION: The patterns of CT and bone scintigraphic findings more likely reflect the size of the mass and ossification, and are not well correlated with the histological grading.

Adult↗
PubMed2004

Molecular epidemiology of measles virus in Japan.

BACKGROUND: Measles virus has been classified into 22 genotypes. The present report examines the molecular epidemiology of measles virus in Japan from 1984 to 2002, and the epidemiological link between imported cases in several foreign countries and Japanese strains was elucidated from the literature. METHODS: B95a or Vero cells was used to isolate the measles virus. The measles virus genome was amplified in the N and H genes by reverse transcriptase-polymerase chain reaction and were partially sequenced. Phylogenetic analysis of a partial sequence of the N gene, from position 1230 to 1685, of the recent measles strains was performed in comparison with the World Health Organization reference strains. RESULTS: There were large outbreaks of measles in Japan in 1984, 1987-1988, 1991-1993, and 2001-2002 and each outbreak was caused by a different genotype. Genotype C1 was an indigenous strain for a long period before 1985, while D3 was isolated in 1987-1988 and D5 in 1991-1993 outbreaks. In addition, the Chicago-type D3 caused sporadic regional outbreaks from 1998 to 1999. After 2000, H1 became the dominant circulating strain. It should be noted that the Japanese strains were detected as imported cases by epidemiological linkage in several countries. CONCLUSIONS: Among the recent circulating strain of measles virus in Japan the genotype H1 was dominant after 2000 and the Japanese strains D3, D5, and H1 were exported to several countries. It is recommended that Japan should adopt a more extensive and active vaccination strategy for measles elimination in line with other countries in the world.

Humans↗