Biomedical subjects

Ning Xiao

Publications and source records attributed to Ning Xiao.

12 recordsLinked to original sources

PubMed2006

Echinococcus multilocularis: developmental stage-specific expression of Antigen B 8-kDa-subunits.

Antigen B (AgB) initially found in hydatid cyst fluid of Echinococcus granulosus is a polymeric lipoprotein of 160 kDa, and is an aggregate of several different but homologous small proteins with approximately 8 kDa. Four genes encoding these 8-kDa-subunits have been identified from E. granulosus. In this study we isolated five genes encoding 8-kDa-subunits of AgB from Echinococcus multilocularis. Sequence comparison of isolated cDNA clones demonstrated that one of these five clones was completely identical to EmAgB8/1 which had been isolated previously by our group, and three of them were 94.5, 90.8, and 91.9% homologous to E. granulosus antigen B 8-kDa subunit genes, EgAgB8/2, EgAgB8/3, and EgAgB8/4, respectively. The remaining clone shared 51-58% homology with the nucleotide sequences of AgB genes. Gene-specific RT-PCR and Western blot analyses revealed that these genes were expressed in a developmentally regulated manner in E. multilocularis vesicles, protoscoleces, and immature adult worms. Possible functions of different expression manners are also discussed.

Amino Acid Sequence↗

PubMed2006

Dual infection of animal hosts with different Echinococcus species in the eastern Qinghai-Tibet plateau region of China.

The eastern Qinghai-Tibet plateau of China is a highly endemic region of echinococcosis where Echinococcus granulosus sensu stricto (sheep strain), Echinococcus multilocularis, and Echinococcus shiquicus are distributed sympatrically. We developed a polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) method for the identification of the three species in this region. The PCR-RFLP showed the dual infection of animals with different Echinococcus spp. The first case was a domestic dog concurrently infected with adults of E. granulosus and E. multilocularis. The second case was a plateau pika (Ochotona curzoniae) harboring metacestodes of E. multilocularis and E. shiquicus in the liver. The high susceptibility of some mammalian hosts to the parasites and the high prevalence of the three co-endemic species probably increase the chance of mixed infections in the eastern Tibetan plateau.

Animals↗

PubMed2005

Recent advances in characterization of Echinococcus antigen B.

Antigen B (AgB) in hydatid cyst fluid of Echinococcus granulosus is a polymeric lipoprotein of 160 kDa and a highly immunogenic major antigen in echinococcal infection. The antigen is comprised of a group of subunit monomers of approximately 8 kDa in molecular size. Recent studies have revealed that the E. granulosus AgB (EgAgB) shows a high degree of genetic variability and the genes encoding the EgAgB 8-kDa subunit monomers that have been identified to date could be grouped into four clades, corresponding to the genes EgAgB8/1, EgAgB8/2, EgAgB8/3 and EgAgB8/4. It has been suggested that the recombinant EgAgB8/2 (rEgAgB8/2) provides better performance in serodiagnosis of human cystic echinococcosis (CE) than does the recombinant EgAgB8/1 (rEgAgB8/1). The EgAgB has been identified as a protease inhibitor with an ability to inhibit recruitment of neutrophils and exploit activation of T helper cells by eliciting a non-protective Th2 cell response, predominantly in patients with progressive CE. Recently it has been revealed that AgB also exists in the cyst fluid of Echinococcus multilocularis. Five different cDNAs encoding the EgAgB homologues have been identified in vesicles, protoscoleces and/or immature adult worms of E. multilocularis and named as EmAgB8/1, EmAgB8/2, EmAgB8/3, EmAgB8/4 and EmAgB8/5. These genes appeared to be expressed in a developmentally regulated manner in the parasite life cycle. This review focuses on recent advances in molecular biological and immunological characterization of AgB from both of E. granulosus and E. multilocularis.

Animals↗

PubMed2005

Usefulness of severe combined immunodeficiency (scid) and inbred mice for studies of cysticercosis and echinococcosis.

The topics in this review are the usefulness of immunodeficient and inbred mice for studies of developmental biology, drug efficacy and host specificity in cysticercosis and echinococcosis. In non-obese diabetic severe combined immunodeficiency (NOD/Shi-scid) mice of both sexes, in vitro hatched oncospheres of all three human taeniid species (Taenia solium, Taenia saginata and Taenia asiatica) developed into cysticerci comparable to or bigger than those developed in their known intermediate host animals, whereas only females were susceptible to these infections in other scid mice of BALB/c, C57BL or C.B-17 inbred strains. Detailed morphological observation from post-oncospheral to cysticercus developmental stages is expected to be easy when we use NOD/Shi-scid mice experimentally inoculated with in vitro hatched oncospheres. Metacestocidal effect of oxfendazole was evaluated in NOD/Shi-scid mice experimentally inoculated with oncospheres of T. solium. In Echinococcus multilocularis infection, larval tissue proliferated without induction of inflammatory host responses in scid mice, thus facilitating isolation of the larval vesicles and protoscoleces for biochemical and molecular biological studies. Trans portal inoculation of metacestode tissues resulted in proliferation of secondary echinococcal foci localized exclusively in the liver without metastasis to other tissues or organs. The advantages of a mouse model for Echinococcus granulosus are also described.

Animals↗

PubMed2005

Echinococcus shiquicus, a new species from the Qinghai-Tibet plateau region of China: discovery and epidemiological implications.

In Shiqu County of the Qinghai-Tibet plateau, many wild and domestic mammals are involved in the transmission cycles of Echinococcus spp. Echinococcus multilocularis and Echinococcus granulosus genotype G1 (sheep strain) are sympatrically distributed in the plateau. In 1995, we identified a unique strobilate stage of Echinococcus from the Tibetan fox, Vulpes ferrilata, but considered it to be a variant of E. multilocularis. Subsequent molecular genetic studies revealed that a hydatid cyst from the plateau pika, Ochotona curzoniae, had unique mitochondrial DNA sequences which are dissimilar to any published sequences of Echinococcus. The same sequences were subsequently found in adult worms from Tibetan foxes. Morphological, genetic and ecological features of the cestode led us to designate a new species Echinococcus shiquicus. E. shiquicus has been found at other areas surveyed on the plateau; however, no infections in humans caused by E. shiquicus have been yet identified.

Animals↗

PubMed2005

Echinococcus shiquicus n. sp., a taeniid cestode from Tibetan fox and plateau pika in China.

The taeniid cestode Echinococcus shiquicus n. sp. was found from the Tibetan fox Vulpes ferrilata and the plateau pika Ochotona curzoniae in the Qinghai-Tibet plateau region of China. In the adult stage, E. shiquicus from the foxes is morphologically similar to Echinococcus multilocularis. However, the new species is differentiated by its smaller rostellar hooks, fewer segments, distinct position of genital pore in the mature segment and fewer eggs in the gravid segment. Hydatid cysts of E. shiquicus found in the livers from the pikas were essentially unilocular but an oligovesicular cyst was also found. The data of mitochondrial and nuclear DNA sequences proved E. shiquicus to be a valid taxon.

Amino Acid Sequence↗

PubMed2005

Short report: Echinococcus multilocularis confirmed on Kunashiri Island, 15 kilometers from the eastern part of Hokkaido, Japan.

There are two foci of alveolar echinococcosis (AE) caused by Echinococcus multilocularis in Japan. The first focus is on Rebun Island where AE patients were found from 1937, and the second is in eastern Hokkaido where patients have been found since the 1960s. The origin of the second focus is unknown. To further investigate AE in eastern Hokkaido, wild rodents (Muridae) were captured and examined for infection on Kunashiri Island, which is located 15 km off the northeastern coast of Hokkaido. Metacestodes of E. multilocularis were isolated from two of 31 voles, all of which were identified to be Clethrionomys rufocanus. Mitochondrial DNA sequencing data of recovered cestodes showed total identity with the cestode reported from Hokkaido. These results suggest that E. multilocularis may have been introduced to Hokkaido from Kunashiri Island during or after 1965.

Animals↗

PubMed2004

The Tibetan hare Lepus oiostolus: a novel intermediate host for Echinococcus multilocularis.

Multicystic hydatids have been found in the livers of hares ( Lepus oiostolus) examined from the Qinghai-Tibet plateau of China. In this study, the causative species was definitively identified as Echinococcus multilocularis by mitochondrial DNA sequencing. This is the first confirmation of larval E. multilocularis from hares. The hydatids contained protoscolices, suggesting that the hare may contribute to the transmission of E. multilocularis on the Tibetan plateau.

Animals↗

PubMed2004

Molecular cloning, expression, and serological evaluation of an 8-kilodalton subunit of antigen B from Echinococcus multilocularis.

Full-length cDNA and genomic DNA encoding an 8-kDa subunit of antigen B from Echinococcus multilocularis (designated EmAgB8/1) were isolated from an E. multilocularis metacestode cDNA library and a protoscolex genomic DNA library, respectively. The open reading frame of the cDNA clone encodes a polypeptide comprising 85 amino acids with a 20-amino-acid NH(2)-terminal signal sequence, which was confirmed following N-terminal sequencing of the native antigen. Reverse transcription-PCR analysis revealed that the clone encoding EmAgB8/1 is predominantly transcribed in larval E. multilocularis. The gene consists of two exons (encoding the signal sequence and mature protein) separated by a 91-bp intron. The mature form was expressed in Escherichia coli, and its antigenic reactivity was compared with that of a counterpart, an 8-kDa subunit of antigen B from Echinococcus granulosus (EgAgB8/1) by Western blotting and enzyme-linked immunosorbent assay (ELISA) with serum samples from patients confirmed to have cystic echinococcosis (CE) and alveolar echinococcosis (AE). Recombinant EmAgB8/1 showed positive reactions in Western blots with 81.3% (65 of 80) of serum samples from CE patients and 40.6% (26 of 64) of serum samples from AE patients, while recombinant EgAgB8/1 showed positive reactions with 86% (43 of 50) and 42% (19 of 45) of the serum samples from these CE and AE patients, respectively. By the ELISA, both EmAgB8/1 and EgAgB8/1 exhibited similar positive reactions with 88% (44 of 50) of serum samples from CE patients and 37.8% (17 of 45) serum samples from AE patients. Statistical analysis revealed that the sensitivity of EmAgB8/1 was comparable to that of EgAgB8/1 for the serodiagnosis of echinococcal diseases. There was no cross-reaction with sera from patients with cysticercosis, which often cross-react when native antigens are used for serodiagnosis.

Amino Acid Sequence↗

PubMed2003

Evaluation of use of recombinant Em18 and affinity-purified Em18 for serological differentiation of alveolar echinococcosis from cystic echinococcosis and other parasitic infections.

To further evaluate recombinant Em18 antigen (rEm18) for immunodiagnosis of human alveolar echinococcosis, 208 serum samples were examined by enzyme-linked immunosorbent assay (ELISA). To comparatively assess the results of rEm18-ELISA, ELISA and immunoblot analysis with two affinity-purified native antigens were also performed with 45 selected serum samples. The results indicate that rEm18 is highly useful for serodiagnosis.

Animals↗

PubMed2003

Short report: Identification of Echinococcus species from a yak in the Qinghai-Tibet plateau region of China.

The species identification of an echinococcal lesion in the liver of a yak in the Qinghai-Tibet plateau region of China, where both Echinococcus granulosus and E. multilocularis are present, was difficult to determine because of the atypical appearance of the lesion. Polymerase chain reaction-based mitochondrial genotyping allowed us to discriminate the Echinococcus species. Nucleotide sequences of the cytochrome c oxidase subunit 1 (cox1) and cytochrome b (cytb) genes amplified from the echinococcal lesion demonstrated that the yak was infected with the E. granulosus G1 genotype (sheep strain).

Animals↗

PubMed2002

Evaluation of an enzyme-linked immunosorbent assay (ELISA) with affinity-purified Em18 and an ELISA with recombinant Em18 for differential diagnosis of alveolar echinococcosis: results of a blind test.

Alveolar echinococcosis (AE) is the most potentially lethal parasitic zoonosis of the nontropical areas in the northern hemisphere, where cystic echinococcosis (CE) is also endemic. Both AE and CE are highly endemic in China, and both serologic detection of echinococcosis, either AE or CE, and differentiation of AE from CE are crucial problems. Evaluation of Western blot analysis (WB) and enzyme-linked immunosorbent assay (ELISA) for the Em18 antigen, using affinity-purified and recombinant Em18, was carried out "blindly" using 60 human sera from patients diagnosed in France. The results were compared with those obtained using a commercially available Echinococcus WB immunoglobulin G (IgG) kit developed in France. The Em18 WB and Echinococcus WB IgG showed very similar results for detection of AE. Both affinity-purified Em18 or a recombinant Em18 WB and Echinococcus WB IgG seem useful for identification of AE, and the latter seems appropriate for both AE and CE, whereas affinity-purified Em18 ELISA and the newly developed recombinant Em18 ELISA appear to be suitable for detection of AE, especially for epidemiological surveys.

Animals↗