Jifei Yang

Chinese Academy of Agricultural Sciences, Peping, Beijing, China

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Publications (29)69.95 Total impact

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    ABSTRACT: Abstract Anaplasma bovis is one of the most important tick-borne pathogens in China. In the first report of A. bovis in China, we describe infection in eight of 17 wild Reeves' muntjac (Muntiacus reevesi) from Guangxi, southwest China.
    Journal of wildlife diseases 08/2014; · 1.27 Impact Factor
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    ABSTRACT: Theileria and Babesia protozoan parasites are transmitted mainly by tick vectors. These parasites cause heavy economic losses to the live-stock industry, as well as affecting the health of wild animals in parasite-endemic areas. Identification of infectious agents in wild animals is not only crucial for species preservation, but also provides valuable information on parasite epidemiology. Here, we conducted a molecular surveillance study in Northwestern China to assess the prevalence of blood pathogens in cervids.
    Parasites & Vectors 05/2014; 7(1):225. · 3.25 Impact Factor
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    ABSTRACT: Haemaphysalis qinghaiensis, a prevalent tick species in China, causes severe economic losses. In this study, we investigated the pathogenicity of six isolates of the fungus Metarhizium anisopliae to engorged female H. qinghaiensis using concentrations of 10(6), 10(7) and 10(8) conidia ml(-1). The results indicated that M.aAT08 and M.aAT13 isolates were highly virulent against the ticks. Metarhizium anisopliae has potential for biocontrol of H. qinghaiensis.
    Experimental and Applied Acarology 03/2014; · 1.85 Impact Factor
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    ABSTRACT: Theileria annulata, the causative agent of tropical theileriosis, is a protozoan parasite that also causes lymphoproliferative diseases in cattle. In vivo, parasitized cells undergo clonal expansion and infiltrate both the lymphoid and non-lymphoid tissues of the infected host. To determine whether the small ruminants and their red blood cells (RBCs) were invaded by T .annulata schizonts or not, T. annulata schizonts were used to infect bovine, ovine and caprine RBCs in vitro, and sheep and goats in vivo. The results showed that the schizonts infected bovine, ovine and caprine RBCs in vitro, but not sheep and goats, which showed only an increase in body temperature and no development of piroplasms. To our knowledge, this is the first report of infection of small ruminants and their RBCs by T. annulata schizonts.
    Experimental Parasitology 12/2013; · 2.15 Impact Factor
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    ABSTRACT: Infections with Theileria sp. may cause significant economic losses to the sheep industry. Species identification based on microscopic examination is difficult, and more suitable methods are required for the rapid detection and identification of Theileria sp, in clinical specimens. In this study, a multiplex polymerase chain reaction (mPCR) assay was developed to simultaneously identify three individual Theileria species in small ruminants. Three pairs of specific, sensitive primers were designed on the basis of the 5.8S ribosomal RNA gene (Theileria luwenshuni and Theileria ovis) and the 18S ribosomal RNA gene (Theileria uilenbergi) to generate target products of 303, 884, and 530 bp, respectively. Standard DNA for each of the three species was extracted from blood recovered from infected sheep, and a preliminary study was conducted on 56 sheep to verify the reliability of the system. Optimal PCR conditions, including primer concentration, annealing time, and the number of amplification cycles, were established. The assay sensitivity under these conditions was 10(-3) % parasitemia, and its specificity was 100 %. The results of the study suggest that mPCR represents a simple, efficient test method as a practical alternative for the rapid detection and identification of Theileria species in small ruminants.
    Parasitology Research 11/2013; · 2.85 Impact Factor
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    ABSTRACT: Species identification using DNA sequences is the basis for DNA taxonomy. In this study, we sequenced the ribosomal large-subunit RNA gene sequences (3,037-3,061 bp) in length of 13 Chinese Theileria stocks that were infective to cattle and sheep. The complete 28S rRNA gene is relatively difficult to amplify and its conserved region is not important for phylogenetic study. Therefore, we selected the D2-D3 region from the complete 28S rRNA sequences for phylogenetic analysis. Our analyses of 28S rRNA gene sequences showed that the 28S rRNA was useful as a phylogenetic marker for analyzing the relationships among Theileria spp. in ruminants. In addition, the D2-D3 region was a short segment that could be used instead of the whole 28S rRNA sequence during the phylogenetic analysis of Theileria, and it may be an ideal DNA barcode.
    The Korean Journal of Parasitology 10/2013; 51(5):511-7. · 0.88 Impact Factor
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    ABSTRACT: Host-parasite coevolution is a key driver of biological diversity. To examine the evolutionary relationships between piroplasmids and their hard tick hosts, we calculated the molecular clock and conducted phylogenetic analyses of both groups. Based on our results, we conclude that the divergence time of piroplasmids (∼56 Mya) is later than divergence time of their hard tick hosts (∼86 Mya). From analyses of the evolution of both piroplasmid and vector lineages and their association, we know that hard ticks transmit piroplasmids with high genus specificity and low species specificity.
    Ecology and Evolution 09/2013; 3(9):2985-2993. · 1.66 Impact Factor
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    ABSTRACT: Here, we conducted an epidemiological study in five regions in central China to assess the impact of theileriosis on small ruminants. PCR analysis and microscopic evaluations of blood smears to detect ovine and caprine theileriosis was conducted, in which 256 blood samples and 250 ticks were collected from sheep and goats, and tested for Theileria uilenbergi, T. luwenshuni, and T. ovis. The 18S rRNA gene sequences were deduced from positive samples and used for phylogenetic analysis. The results showed that T. luwenshuni was found most frequently in the five investigated regions and the prevalence of T. luwenshuni was found to be very high by PCR analysis. In contrast, T. uilenbergi and T. ovis infections were not detected in these regions. Phylogenetic tree analysis showed that all of the newly isolated Theileria spp. was in the same clade as T. luwenshuni. Haemaphysalis longicornis, which can transmit T. luwenshuni, was also detected in the sampled sheep and goats in these regions. Our results provide important data to increase the understanding of the epidemiology of ovine and caprine theileriosis, and will aid in the implementation of measures to control theileriosis transmission to small ruminants in central China.
    Veterinary Parasitology 07/2013; · 2.38 Impact Factor
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    ABSTRACT: BACKGROUND: Various genospecies of Borrelia burgdorferi sensu lato (s.l.) have been identified from patients and animals worldwide. Genospecies-related dissemination of disease has been reported. The present study aimed to elucidate the pathogenicity of infections caused by B. garinii SZ isolated in China. B. burgdorferi B31 and B. afzelii BO23 were used for comparison. METHODS: Spirochete load in blood and tissue samples of infected mice were measured by minor groove binder-based real-time polymerase chain reaction. The kinetics of spirochete dissemination and disease severity were assessed in BALB/c mice. RESULTS: The pattern of bacterial load differed between the three genospecies. The B. garinii SZ strain is highly pathogenic and can trigger multi-system pathological damage in mice. CONCLUSIONS: Spirochete dissemination, persistence, tissue tropism and disease severity varied significantly, suggesting that different genospecies may play an important role in the pathogenicity and development of clinical diseases.
    Parasites & Vectors 06/2013; 6(1):177. · 3.25 Impact Factor
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    ABSTRACT: Currently, the most efficient and widely used method for tick control is the application of acaricides, especially deltamethrin and alpha-cypermethrin, two pyrethroids with neurotoxic action. In this study, the in vitro efficacy of deltamethrin and alpha-cypermethrin was assessed on engorged female Haemaphysalis qinghaiensis ticks. An in vitro bioassay (adult immersion test) was carried out to determine the LC (lethal concentration) 50 and LC90 of both compounds, calculated by probit analysis. The LC50 and LC90 values of deltamethrin and alpha-cypermethrin were 5.67 (LC50) and 51.72 ppm (LC90), and 166.56 (LC50) and 1366.69 ppm (LC90), respectively. This study provides important information on the efficacy of deltamethrin and alpha-cypermethrin for the control of H. qinghaiensis.
    Experimental Parasitology 04/2013; · 2.15 Impact Factor
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    ABSTRACT: Molecular phylogenetic analyses are mainly based on the small ribosomal RNA subunit (18S rRNA), internal transcribed spacer regions, and other molecular markers. We compared the phylogenetic relationships of Babesia spp. using large subunit ribosomal RNA, i.e., 28S rRNA, and the united 28S + 18S rRNA sequence fragments from 11 isolates of Babesia spp. collected in China. Due to sequence length and variability, the 28S rRNA gene contained more information than the 18S rRNA gene and could be used to elucidate the phlyogenetic relationships of B. motasi, B. major, and B. bovis. Thus, 28S rRNA is another candidate marker that can be used for the phylogenetic analysis of Babesia spp. However, the united fragment (28S + 18S) analysis provided better supported phylogenetic relationships than single genes for Babesia spp. in China.
    Experimental and Applied Acarology 11/2012; · 1.85 Impact Factor
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    ABSTRACT: Rhipicephalus (Boophilus) microplus, an important ectoparasite that can transmit Babesia and Anaplasma, has caused inestimable economic losses around the world. Traditionally, acaricides are used for the control of ticks. However, drawbacks of chemical control, such as resistance, environmental pollution, and traces in food promote alternative strategies to pesticides. Microbial control is one option to reduce tick populations. In this study, we investigated the pathogenicity of thirteen Beauveria bassiana isolates and seven Metarhizium anisopliae isolates to the engorged female R. (B.) microplus ticks using different conidial concentrations of 107, 108 and 109 conidia mL–1. Fourteen days after treatment, three B. bassiana isolates (B.bAT01, B.bAT03, B.bAT13) and one M. anisopliae isolate (M.aAT04) resulted in 100% mortality of engorged female ticks with conidial concentrations of 108 and 109 conidia mL–1. Isolates of B.bAT01, B.bAT03, B.bAT13 and M.aAT04 at all conidial concentrations could reduce the reproductive efficiency index (REI) of R. (B.) microplus ticks.
    Biological Control 11/2012; 63(2):98–101. · 1.92 Impact Factor
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    ABSTRACT: The developmental stages in the life cycle of Haemaphysalis qinghaiensis were investigated under laboratory conditions. The larval, nymphal and adult ticks were fed on sheep at 25-27 °C, 50 % relative humidity (RH) and exposed to daylight. All free-living stages were maintained in an incubator (28 °C with 90 % RH and a 12-h photoperiod). The whole life cycle of H. qinghaiensis was completed in an average of 176 days (range 118-247 days). The average developmental periods were 34.44 days for egg incubation; 5.83, 4.20 and 33.70 days for larval pre-feeding, feeding and pre-molting; and 3.88, 5.30 and 46.50 days for nymphal pre-feeding, feeding and pre-molting. The average times for pre-feeding, feeding, pre-oviposition and oviposition of female adult ticks were 2.60, 11.40, 8.50, and 19.35 days, respectively. The results confirmed the positive correlation between the weight of the engorged female and the egg mass laid (r = 0.557, P < 0.05). The reproductive efficiency index and reproductive fitness index in females were 5.49 and 4.98, respectively. Engorged nymphs moulting to females (4.53 ± 0.16 mg) were significantly heavier (P < 0.001) than those moulting to males (3.45 ± 0.19 mg). The overall sex ratio of the adult ticks was 1:1.1 (M:F).
    Experimental and Applied Acarology 10/2012; · 1.85 Impact Factor
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    ABSTRACT: The zoonotic rickettsial pathogen Anaplasma phagocytophilum has a broad geographic distribution and a high degree of biological and clinical diversity. To determine the prevalence of A. phagocytophilum in the Gannan Tibet Autonomous Prefecture of Gansu province, northwestern China, four species of ruminants, rodents and ticks were examined for A. phagocytophilum infection. DNA from A. phagocytophilum was detected by nested PCR in blood samples from 21/49 (42.9%) sheep, 35/91 (38.5%) goats, 51/158 (32.3%) yaks, 7/20 (35.0%) cattle-yaks, and in spleen samples from 2/12 (16.7%) rodents. For samples from tick larvae and nymphs, 105 pools were tested; 1 of 46 larval tick pools was positive; 7 of 59 nymphal tick pools was positive. For adult ticks, 40/598 (6.7%) female ticks and 26/528 (4.9%) male ticks were positive. The prevalence of A. phagocytophilum in female ticks was higher than that in male ticks, although the difference was not statistically significant (P > 0.05). Sequences analysis based on 16S rRNA gene indicated that the strains in the study area were distinct from previously reported A. phagocytophilum in other continents. These results add new information on the epidemiology of A. phagocytophilum and indicate the tick-animal cycle of anaplasmosis in the area. To our knowledge, this is the first report of A. phagocytophilum infection in Gansu Province in northwestern China.
    Journal of Medical Microbiology 10/2012; · 2.30 Impact Factor
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    ABSTRACT: TO THE EDITOR: Rickettsia raoultii is an obligate intracellular gram-negative bacterium belonging to the spotted fever group (SFG) of the genus Rickettsia. Genotypes RpA4, DnS14, and DnS28, originally isolated from ticks from Russia in 1999 (1), were designated as Rickettsia raoultii sp. nov. on the basis of phylogenetic analysis (2). R. raoultii has been found mainly in Dermacentor spp. ticks in several countries in Europe (3). It was detected in a Dermacentor marginatus tick from the scalp of a patient with tick-borne lymphadenitis in France (2), which suggests that it might be a zoonotic pathogen. We determined the prevalence of R. raoultii-like bacteria in Dermacentor spp. in highland regions in Tibet.
    Emerging Infectious Diseases 09/2012; 18(9):1532-4. · 6.79 Impact Factor
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    ABSTRACT: The present study developed and validated a species-specific loop-mediated isothermal amplification (LAMP) assay for the rapid detection and discrimination of two benign bovine Theileria species -T. sergenti and T. sinensis. The LAMP assay is inexpensive and easy to perform and involves a rapid reaction-the amplification can be performed in 55min or 50min under isothermal conditions of 61°C or 63°C, respectively, by employing a set of four species-specific primer mixtures. The results can be checked using agarose gels. The optimal assay conditions, under which the assay exhibited with no cross-reaction with other closely related tick-borne parasites (T. annulata, Babesia bovis, B. bigemina, B. major, B. ovata, B. U. sp., Anaplasma marginale) or between the two Theileria species of interest, was established. The assay is approximately 10-fold more sensitive than the conventional specific PCR assay. The LAMP assay was validated using DNA from 6 standard stocks in the laboratory and was evaluated for its diagnostic utility using blood samples collected from experimentally and naturally infection cattle or yaks in China. These findings indicate that this Theileria species-specific LAMP assay may have potential clinical applications for the detection and differentiation of two benign bovine Theileria species -T. sergenti and T. sinensis, especially in endemic countries.
    Veterinary Parasitology 08/2012; · 2.38 Impact Factor
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    ABSTRACT: Bovine babesiosis is a tick-transmitted hemoprotozoan disease that is mainly caused by Babesia bovis and/or Babesia bigemina and is characterized by significant morbidity and mortality worldwide. This disease is widespread in most parts of China. However, it is difficult to rapidly discriminate between the B. bovis and B. bigemina species. To detect and distinguish these species, a loop-mediated isothermal amplification (LAMP) platform that targets specific sequences of the internal transcribed spacer (ITS) genes was developed. Specificity testing revealed that there was no cross-reaction with the other tick-borne parasites B. ovate, B. major, unnamed bovine Babesia, Theileria annulata, Theileria sinensis, Theileria sergenti, and Anaplasma marginale, or with bovine white blood cells. The sensitivity of the LAMP method was 0.1pg DNA for both B. bovis and B. bigemina, which was superior to that of the classical PCR methods. This assay was evaluated for its diagnostic utility using blood samples collected from experimentally and naturally infected cattle in China. These findings indicate that the Babesia species-specific LAMP assay may have potential clinical application in the detection and differentiation of Babesia species, particularly in countries in which babesiosis is endemic.
    Parasitology International 07/2012; 61(4):658-63. · 2.30 Impact Factor
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    ABSTRACT: Due to the difficulty in morphological identification the development of reliable molecular tools for species distinction is a priority for piroplasma. Previous studies based on 18S rRNA and other gene sequences provided a backbone for the phylogeny of piroplasma. However, it is difficult to discriminate species in a comprehensive sample. Here, the abilities of eight DNA regions including 18S rRNA, 28S rRNA, internal transcribed spacer (ITS) regions and COI genes, have been compared as candidates of DNA barcodes for piroplasma. In total, 484 sequences of piroplasma were collected from this study and GenBank. The eight proposed DNA regions were evaluated according to the criterion of Consortium for the Barcode of Life (CBOL). From this evaluation, ITS2 had 100% PCR amplification efficiency, an ideal sequence length, the largest gap between the intra- and inter-specific divergence, 98% identification efficiency at the genus level, and 92% at the species level. Thus, we propose that ITS2 is the most ideal DNA barcode based on the current database for piroplasma.
    Acta tropica 07/2012; 124(1):92-7. · 2.79 Impact Factor
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    ABSTRACT: Babesia sp. in Xinjiang, transmitted by Hyalomma, is a large Babesia that is infective for small ruminants, but it has almost no pathogenicity in healthy sheep. On the basis of the sequences of the 18S rRNA and internal transcribed spacer (ITS) genes, morphological characteristics, vector tick species and pathogenicity it was identified recently as a novel Babesia species. In the present study, an enzyme-linked immunosorbent assay (ELISA) was developed using soluble merozoite antigens of Babesia sp. in Xinjiang (BXJMA) derived from in vitro culture. When the positive threshold was chosen as 24.65% of the specific mean antibody rate, the specificity and sensitivity were both 97.3%. There was no cross-reaction between BXJMA and positive sera from sheep infected with other Chinese ovine piroplasms or Anaplasma ovis in the ELISA and western blotting. Specific antibodies against Babesia sp. in Xinjiang could be detected 2weeks post infection and a high level of antibodies persisted for more than 12weeks in experimentally infected sheep. The ELISA was tested on 3857 sera collected from small ruminants in 50 prefectures of 22 provinces to evaluate the sero-epidemiology of Babesia sp. in Xinjiang infection, and the average positive rate was 31.66%. These data provide that the developed ELISA is a powerful tool for the sero-diagnosis of Babesia sp. in Xinjiang and confirm that it is a novel species.
    Parasitology International 05/2012; 61(4):532-7. · 2.30 Impact Factor
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    ABSTRACT: Borrelia burgdorferi sensu lato (s. l.), the agent of Lyme disease, is distributed widely worldwide. A large number of polymerase chain reaction (PCR) methods have been developed and used for detection of B. burgdorferi s. l. However, there is a lack of a reference standard because of the genetic diversity of the B. burgdorferi s. l. complex. In this study, 4 PCR methods, based on the OspA, flagellin, rrs, and P66 genes, for detection of B. burgdorferi s. l. were evaluated by detection of genomic DNA from 3 reference genospecies and tick samples. The sensitivity of the PCR methods was analyzed using serially diluted gDNA from B. afzelii (Bo23), B. burgdorferi sensu stricto (B31), and B. garinii (PBi). The performance of the PCRs was evaluated by detection of the gDNA of 543 ticks. The results showed that the PCRs targeting the OspA gene, fla gene, rrs gene, and P66 gene detected 37 (6.8%), 74 (13.6%), 16 (2.9%), and 14 (2.6%) tick samples, respectively. The PCR targeting the fla gene was the most sensitive method for the detection of B. burgdorferi s. l.
    Diagnostic microbiology and infectious disease 04/2012; 73(1):80-3. · 2.45 Impact Factor