Entity

Time filter

Source Type


Yanase T.,Japanese National Institute of Animal Health | Matsumoto Y.,Japan National Institute of Agrobiological Science | Matsumori Y.,Goto Livestock Hygiene Service Center | Aizawa M.,Okinawa Prefectural Institute of Animal Health | And 6 more authors.
Journal of Medical Entomology | Year: 2013

Although Culicoides biting midges act as a vector of important human and domestic animal diseases, their ecology is poorly understood. The lack of proper identification systems of Culicoides larvae is one of the main obstacles to progress in research. Based on mitochondrial sequences of 19 Japanese Culicoides species, we designed a universal primer set to amplify the partial sequence of the mitochondrial cytochrome c oxidase I (cox 1). The polymerase chain reaction product amplified from extracted DNA of Culicoides larvae using the primer set was directly sequenced, and species identification based on the variation at cox1 was conducted. Using the molecular identification system, we sorted 243 specimens of field-collected larvae from the southern part of Japan into 10 species including Culicoides arakawae (Arakawa), Culicoides oxystoma Kieffer, and Culicoides brevitarsis Kieffer, which are regarded as vectors of important livestock animal diseases. Eight species of Culicoides larvae, including C. arakawae and C. oxystoma, were recovered from active paddy fields and an abandoned paddy field. The result suggests that paddy fields contribute to breeding a variety of Culicoides species and maintenance and spread of Culicoides-borne pathogens. In contrast, larvae of C. brevitarsis were collected from cattle dung in pastures. The molecular identification system described herein using nucleotide sequences successfully achieved larval identification and will be useful for a better understanding of larval habitats of Culicoides biting midges. © 2013 Entomological Society of America.


Yanase T.,Japanese National Institute of Animal Health | Aizawa M.,Okinawa Prefectural Institute of Animal Health | Kato T.,Japanese National Institute of Animal Health | Yamakawa M.,Japanese National Institute of Animal Health | And 2 more authors.
Virus Research | Year: 2010

Sequence determination and phylogenetic analysis were conducted using the S, M and L RNA segments of the 10 Aino, 6 Peaton and 1 Sango virus (AINOV, PEAV and SANV) field isolates of the genus Orthobunyavirus in the family Bunyaviridae, respectively. The Japanese AINOV strains were genetically stable, but the sequence differences between the Japanese and Australian AINOV strains were considerably larger than those among the Japanese AINOV strains. A similar result was found in the genetic relationship among Japanese and Australian PEAVs, and SANV which was isolated in Nigeria and was thought as a synonym of PEAV, suggesting that geographic separation contributed significantly to the evolution of those viruses. The Australian AINOV strain B7974 is more closely related to the Australian PEAV strain CSIRO110 than to the Japanese AINOV strains in the S and L RNA segments, while the phylogenetic position of the M RNA segment of the B7974 strain was clustered with those of the Japanese AINOV strains. Our findings indicate that the B7974 strain is a reassortment with the M RNA segment derived from AINOV and the S and L RNA segments derived from an Australian PEAV. © 2010 Elsevier B.V.


Sivakumar T.,Obihiro University of Agriculture and Veterinary Medicine | Tattiyapong M.,Obihiro University of Agriculture and Veterinary Medicine | Okubo K.,Obihiro University of Agriculture and Veterinary Medicine | Suganuma K.,Obihiro University of Agriculture and Veterinary Medicine | And 6 more authors.
Ticks and Tick-borne Diseases | Year: 2014

Babesia ovata is a tick-transmitted hemoprotozoan parasite of cattle. In the present study, we analyzed tick DNA samples (n= 1459) prepared from questing ticks collected from various cattle pastures in Hokkaido (Shibecha, Taiki, Otofuke, Memuro, and Shin-Hidaka districts) and Okinawa (Yonaguni Island) prefectures of Japan for B. ovata. When all the tick DNA samples were screened by a previously described B. ovata-specific apical membrane antigen-1 (AMA-1) gene-based polymerase chain reaction (PCR) assay, none of the DNA samples was positive. Therefore, we developed a PCR assay based on the protozoan beta-tubulin (β-tubulin) gene to detect B. ovata from ticks in Japan. In the specificity test, the PCR assay amplified the expected 444-bp target gene fragment from B. ovata DNA. No PCR products were amplified from DNA samples from other blood pathogens, bovine blood, or ticks. In addition, the PCR assay detected 100. fg of B. ovata-genomic DNA extracted from an in vitro culture of the parasites. Subsequently, when all the tick DNA samples were screened by this new PCR assay, 18 were positive for B. ovata. Positive samples were found only in the Yonaguni and Memuro areas. In Okinawa, where all the ticks were identified as Haemaphysalis longicornis, 9.7% of the samples were PCR-positive, while a single tick (Ixodes ovatus) from Memuro was infected with B. ovata. When the nucleotide sequences of the PCR amplicons were phylogenetically analyzed, they formed a separate clade containing a previously described β-tubulin gene sequence from B. ovata (Miyake strain), confirming that the PCR assay had detected only B. ovata from the tick DNA samples. This is the first report that describes the PCR detection of B. ovata in ticks. The findings warrant transmission experiments to evaluate I. ovatus as a potential vector of B. ovata. © 2014 Elsevier GmbH.


Kyan H.,Okinawa Prefectural Institute of Health and Environment | Taira M.,Okinawa Prefectural Institute of Health and Environment | Yamamoto A.,Okinawa Prefectural Institute of Health and Environment | Inaba C.,Okinawa Prefectural Institute of Health and Environment | Zakimi S.,Okinawa Prefectural Institute of Animal Health
Japanese Journal of Infectious Diseases | Year: 2012

Toxoplasma gondii genotypes were isolated and characterized from cephalic muscle samples collected from 24 goats slaughtered at an abattoir in Okinawa between 2008 and 2009. Of the 24 samples assayed using latex agglutination, 18 were seropositive, 2 were pseudo-positive, and 4 were seronegative against T. gondii antibodies. The samples were then inoculated into laboratory mice to isolate the parasite. Among the isolated samples, 13 (72.2% of the 18 seropositive strains in the latex agglutination assay) were seropositive, 1 (50%) was pseudo-positive, and none were seronegative. However, after being frozen and stored at -20°C, all samples were found to be T. gondii-free. Of the 14 isolates of the GRA6 genotype, 6 were of type I, 7 were of type II, and 1 was of type III; the genotype distribution ratio was similar to that of T. gondii strains isolated from locally raised pigs. Moreover, no sulfonamide-tolerant dhps gene mutant of T. gondii was detected.


Yokoyama N.,Obihiro University of Agriculture and Veterinary Medicine | Sivakumar T.,Obihiro University of Agriculture and Veterinary Medicine | Ota N.,Obihiro University of Agriculture and Veterinary Medicine | Igarashi I.,Obihiro University of Agriculture and Veterinary Medicine | And 12 more authors.
Infection, Genetics and Evolution | Year: 2012

In the present study, we investigated the possible tick vectors that can transmit Theileria orientalis in eastern Hokkaido, Japan. Questing ticks collected from three different districts, Taiki, Otofuke, and Shin-Hidaka, of Hokkaido included Ixodes persulcatus, Haemaphysalis megaspinosa, Haemaphysalis douglasi, and Ixodes ovatus, while all the ticks collected from Yonaguni island of Okinawa were identified as Haemaphysalis longicornis. When the ticks were screened by polymerase chain reaction (PCR) for T. orientalis, the parasite was commonly detected among all tick species. Genotype-specific PCR assays revealed that all tick species in Hokkaido were predominantly detected with type 2, while ticks collected from Okinawa (H. longicornis) were predominantly detected with type 1. Consistent with the genetic diversity of T. orientalis in ticks, genotyping PCR assays from cattle grazed in the same Hokkaido sampling locations identified type 2 as the most prevalent genotype. This study provides the first identification of I. persulcatus, H. megaspinosa, H. douglasi, and I. ovatus as possible tick vectors of T. orientalis, and finds that the variety of vectors apparently capable of transmitting T. orientalis is wider in Japan than expected. The authors suggest that tick control strategies should be modified in Hokkaido based on the seasonal activities of ticks identified in the present study. © 2012 Elsevier B.V.

Discover hidden collaborations