Rickettsiae belongs to the order Rickettsiales, whose members were described as obligate intracellular gramnegative microorganisms. Several species cause diseases in humans and other vertebrate or invertebrate hosts, and have a worldwide distribution. For the last 15 years, nine new rickettsiosis have been reported, that is, Japanese spotted fever caused by Rickettsia japonica (19,39), Flinders Island spotted fever caused by R. honei (33,34), Astrakhan tick bite fever caused by Astrakhan fever rickettsia (5), African tick bite fever caused by R. africae (15), California flea typhus caused by R. felis (the ELB agent) (35), and four other unnamed spotted fevers caused by R. mongolotimonae (30,44), R. slovaca (18, 31, 36), R. helvetica (11, 25), and "R. heilongjiangii," (17, 45) respectively. In Japan, 63 tick-associated rickettsiae strains, belonging to at least three serotypes, have been isolated over the last several years (8-10), including R. japonica isolated from the Dermacentor taiwanensis and Haemaphysalis frava ticks, respectively; R. helvetica (strains IP-1 and IM-1), strains Abstract: 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...

Rickettsiae belong to the order Rickettsiales, whose members are described as obligate intracellular gram-negative microorganisms. Several species cause diseases in human and in other vertebrate or invertebrate hosts, and have a worldwide distribution. The genus Rickettsia is presently divided into two groups: the typhus group (TG), which includes three species (Rickettsia prowazekii, Rickettsia typhi, and Rickettsia canada), and the spotted fever group (SFG). The number of recognized members of the SFG rickettsiae increased following the development of an improved cell culture isolation technique (the shell vial technique) (19) and interest in arthropodtransmitted diseases gradually increased. New SFG rickettsiae have been isolated from arthropods worldwide, including Rickettsia massiliae isolated in France and Greece (3 5), Rickettsia mongolotimonae (strain HA-91) in the People's Republic of China (35), strain Bar29 in Spain (7), Rickettsia aeschlimannii (strain MC16) in Morocco (8), Rickettsia helvetica in Switzerland (6), Rickettsia peacockii in Montana, U.S.A. (20), and strain AB Bacterium in England (33) (this strain has been characterized by genomic criteria but it remains unisolated). In addition, new SFG rickettsiae from humans have been reported, including Rickettsia africae in Zimbabwe (18), Rickettsia japonica in Japan (31), Rickettsia felis in Texas, U.S. A. (17, 29), the Astrakhan fever rickettsia in Russia (10), Rickettsia honei in Australia (30), and R. mongolotimonae in France (28). Recently, we isolated 8 SFG rickettsiae from ticks in Japan (13 15). In order to elucidate the phylogenetic location of these isolates, we amplified, and sequenced the fragments of both the gltA and rOmpA genes by PCR and an automated laser fluorescent DNA sequencer. Here we report the results of phylogenetic analysis, comparing the sequences of these isolates with those from recognized Rickettsia species. Materials and MethodsRickettsiae. Eight strains isolated from the ticks in Japan are shown in Table 1. As reference strains, R. Abstract: 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 ...

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Seventy-eight poliovirus strains isolated from river water and sewage in Toyama Prefecture, Japan, during 1993 to 1995 were characterized by the PCR-restriction fragment length polymorphism (RFLP) method and by partially sequencing the VP3 and VP1 regions of the viral genome. Of these isolates, 36 were identified as Sabin vaccine strains, and 42 were identified as vaccine variant strains that had less than 1.4% nucleotide divergence from the Sabin strains, including 7 isolates with patterns different from those of Sabin strains as determined by PCR-RFLP analysis. These findings suggest that wild-type poliovirus was not circulating in Toyama Prefecture.

Nineteen echovirus 11 (E11) and 12 E13 isolates were isolated from three rivers in Toyama Prefecture, Japan, during an environmental surveillance conducted from April 2002 to March 2003. The nucleotide sequences of E13 isolates were closely related to those from patients with aseptic meningitis, with less than 1.3% divergence in the VP1 region of the viral capsid gene, and belonged to the same clade responsible for a worldwide outbreak that started in 2000. In contrast, E11 isolates were clustered into three genomic groups and were not closely related to echovirus strains isolated from patients. These results suggest that the combination of both virus isolation from environmental sources and phylogenetic analysis could be complementary assessment approaches to trace prevalent and minor circulating enteroviruses in the human population.