Biomedical subjects
Publications and source records attributed to Shuji Ando.
Rickettsia was first detected in seabird soft-bodied ticks, Carios capensis and C. sawaii in Japan. According to sequence analysis, Rickettsia in Japan was identical to Rickettsia scc31 in C. capensis in the U.S.A. This suggested that an environmental circulation had consisted among microorganisms, ticks and long distance migratory seabirds around the Pacific Ocean.
In March 2004, we experienced an outbreak of Chlamydia pneumoniae infection on an islet of Korea. In order to assess the significance of the epidemic, we performed a mass examination of 137 students (7-16 years old; male, 69; female, 58) at a school. The examination consisted of a questionnaire inquiring about respiratory symptoms, a serum antibody test for C. pneumoniae using a microimmunofluorescence (MIF) method and enzyme-linked immunosorbent assay (ELISA), and nasopharyngeal swab tests to detect of the organism by specific PCR and cell culture. The results demonstrated that 72 (58.3%) of the students had respiratory symptoms such as rhinorrhea, a sore throat, and/or cough or fever. The PCR positivity of acute-phase patients was 63% (12/19) and PCR positivity using the culture sample was 94% (18/19). However, the existence of the organism was not confirmed fluorescein isothiocyanate (FITC). ELISA, one of the serological methods utilized, demonstrated, in the same patients, 48% (13/27) positive IgM antibodies at the acute phase of the outbreak, and 16% (3/19) positive IgM antibodies during the convalescent phase. The index value (ID) 3.0 for single-sera IgG was 19% (5/27) and that for IgA was 4% (1/27) at the acute phase; the corresponding percentages in the convalescent phase were 11% (2/19) and 5% (1/19), respectively. However, as regards paired sera, no patient demonstrated a 1.35 ELISA ID value at 2 weeks, or an increased value of 1.0 at 8 weeks after the onset of the outbreak. In the MIF experiment, the percent positivity of unpaired IgM from the acute phase was 58% (11/19). At convalescent phase, this percentage was 47% (9/19); however, the positivity of paired serum IgG was 26% (5/19). In the same sample, the percentage of positive cases demonstrated by both ELISA and MIF approaches for single IgM was 37% (7/19) at the acute phase and 11% (2/19) at the convalescent phase. We were unable to isolate C. pneumoniae by cell culture, but we did obtain sufficient serological and PCR data to consider C. pneumoniae as the causative agent of the outbreak. Meaningful results were acquired in terms of serology, and were compared to the healthy population in Korea. Although it remains necessary to investigate the possibility of co-infection and to determine whether or not this outbreak coincides with the prevalence of influenza, it was unequivocally concluded that this outbreak of C. pneumoniae infection has occurred on an islet of Korea.
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Although the correlates of vaccine-induced protection against human immunodeficiency virus type 1 (HIV-1) are not fully known, it is presumed that neutralizing antibodies (NAb) play a role in controlling virus infection. In this study, we examined immune responses elicited in rhesus macaques following vaccination with recombinant Mycobacterium bovis bacillus Calmette-Guérin expressing an HIV-1 Env V3 antigen (rBCG Env V3). We also determined the effect of vaccination on protection against challenge with either a simian-human immunodeficiency virus (SHIV-MN) or a highly pathogenic SHIV strain (SHIV-89.6PD). Immunization with rBCG Env V3 elicited significant levels of NAb for the 24 weeks tested that were predominantly HIV-1 type specific. Sera from the immunized macaques neutralized primary HIV-1 isolates in vitro, including HIV-1BZ167/X4, HIV-1SF2/X4, HIV-1CI2/X4, and, to a lesser extent, HIV-1MNp/X4, all of which contain a V3 sequence homologous to that of rBCG Env V3. In contrast, neutralization was not observed against HIV-1SF33/X4, which has a heterologous V3 sequence, nor was it found against primary HIV-1 R5 isolates from either clade A or B. Furthermore, the viral load in the vaccinated macaques was significantly reduced following low-dose challenge with SHIV-MN, and early plasma viremia was markedly decreased after high-dose SHIV-MN challenge. In contrast, replication of pathogenic SHIV-89.6PD was not affected by vaccination in any of the macaques. Thus, we have shown that immunization with an rBCG Env V3 vaccine elicits a strong, type-specific V3 NAb response in rhesus macaques. While this response was not sufficient to provide protection against a pathogenic SHIV challenge, it was able to significantly reduce the viral load in macaques following challenge with a nonpathogenic SHIV. These observations suggest that rBCG vectors have the potential to deliver an appropriate virus immunogen for desirable immune elicitations.
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Epizootiological surveys on hantavirus infections in rodents were carried out in various areas of Japan, including the four major islands of Hokkaido, Honshu, Shikoku, and Kyushu from 2000 to 2003. A total of 1,221 rodents and insectivores were captured. Seropositive animals were found in Apodemus (A.) speciosus (5/482, 1.0%), Rattus (R.) norvegicus (4/364, 1.1%), R. rattus (3/45, 6.7%), and Clethrionomys (C.) rufocanus (7/197, 3.6%). The partial S segment was amplified from one seropositive R. rattus captured at Hakodate. The nucleotide sequence showed 96% identity with the Seoul virus (SEOV) prototype strain SR-11. In addition, we conducted an epidemiological survey on human hantavirus infection in a high-risk population, the personnel of the Japan Ground Self-defense Force on Hokkaido. One out of 207 human blood samples was positive for anti-hantavirus antibody by IFA, ELISA, and WB analysis. The result of the serotype specific ELISA indicates that this individual acquired SEOV infection. This study indicates that A. speciosus, R. norvegicus, R. rattus, and C. rufocanus carry hantaviruses as the reservoir animals in Japan. Infected R. rattus and R. norvegicus in port areas could be the sources of human SEOV infection and a threat to travelers and individuals working in seaports.
In order to understand the natural situation of rickettsiae in the ticks in Japan, the rickettsial genes, gltA gene, rOmpA gene, and 17-kDa gene, were amplified from the ticks by nested PCR. The prevalences of rickettsial gltA genes among Haemaphysalis formosensis, H. longicornis, H. megaspinosa, Ixodes ovatus, H. flava, H. kitaokai, and I. persulcatus were 62, 57, 24, 24, 19, 13, and 10%, respectively; 26% (186/722) being the average. The gltA genes amplified from the ticks were classified into 9 genotypes (I to IX) by the difference in nucleotide sequences. Genotype I was detected from 7 species of ticks. Genotype II mainly was detected from H. longicornis and H. formosensis. Genotypes III and VII mainly were detected from H. flava and I. ovatus. The polarization in the distribution of genotypes among regions where the ticks were collected was not clear. Based on the phylogenetic analysis of the three genes presented here, genotypes I, III, and IV (detected from H. formosensis, H. hystricia, and I. ovatus ) are genetically close with each other, but rickettsiae of the same property still have not been isolated from ticks anywhere in the world. These genotypes should be considered as new species among SFG rickettsiae. Genotype II was identical with strain FUJ-98, genetically close to R. japonica which has been isolated from ticks in China. Genotype V was identical with R. felis and strain California 2 isolated from the cat flea. This is the first report on the detection of R. felis from ticks. Genotype VI detected from Ixodes sp. did not seem to belong to genus Rickettsia. Based on the previous antigenic data and the phylogenetic analysis presented here, Genotype VII should be considered a variant of R. helvetica and genotype VIII detected from I. ovatus and I. persulcatus were identical with R. helvetica. Genotype IX detected from I. nipponensis was genetically close to the strains IRS3, IRS4, and IrR/Munich isolated from I. ricinus in Slovakia and German.
Eight spotted fever group (SFG) rickettsiae isolated from ticks in Japan were classified by phylogenetic analysis based on the nucleotide sequences of both the citrate synthase-encoding gene (gltA) and 190-kDa antigen-encoding gene (rOmpA). In the phylogenetic tree of gltA, strains DT-1 and FLA-1 isolated from the Dermacentor taiwanensis and Haemaphysalis frava ticks, respectively, were placed as Rickettsia japonica, and strains IO-1, IO-2, IO-25, IM-1 and IP-2 from genus Ixodes ticks were placed as Rickettsia helvetica. Strain AT-1 isolated from the Amblyomma testudinarium belonged to the cluster including Rickettsia akari, Rickettsia australis and Rickettsia felis. In the phylogenetic tree of the rOmpA, strains DT-1 and FLA-1 were placed as R. japonica, and strain AT-1 belonged to the cluster including Rickettsia cooleyi and the symbiont of Ixodes scapularis. The rOmpA fragments of 5 Ixodes isolates could not be amplified by PCR. The present study showed that strains DT-1 and FLA-1 were genotypically identical to R. japonica, and 5 Ixodes isolates were associated with the R. helvetica. Based on previous genotypic and antigenic data, and the phylogenetic analysis presented here, strain AT-1 should be considered as a new species among SFG rickettsiae.