The RIO protein kinase-encoding gene Sj-riok-2 is involved in key reproductive processes in Schistosoma japonicum.

BACKGROUND: Schistosomiasis is one of the most prevalent parasitic diseases worldwide and is caused by parasitic trematodes of the genus Schistosoma. The pathogenesis of schistosomiasis is caused by eggs whose production is the consequence of the pairing of schistosomes and the subsequent sexual maturation of the female. Previous studies have demonstrated that protein kinases are involved in processes leading to the male-induced differentiation of the female gonads, ovary and vitellarium. Right open reading frame protein kinase 2 (RIOK-2) is a member of the atypical kinase family and shown in other organisms to be responsible for ribosomal RNA biogenesis and cell-cycle progression, as well as involves in nematode development. However, nothing is known about its functions in any trematode including schistosome. METHODS: We isolated and characterized the riok-2 gene from S. japonicum, and detected the transcriptional profiles of Sj-riok-2 by using real-time PCR and in situ hybridization. RNAi-mediated knockdown of Sj-riok-2 was performed, mitotic activities were detected by EdU incorporation assay and morphological changes on organs were observed by confocal laser scanning microscope (CLSM). RESULTS: In silico analyses of the amino acid sequence of Sj-RIOK-2 revealed typical features of this class of kinases including a winged helix (wHTH) domain and a RIO kinase domain. Sj-riok-2 is transcribed in different developmental stages of S. japonicum, with a higher abundance in adult females and eggs. Localization studies showed that Sj-riok-2 was mainly transcribed in female reproductive organs. Experiments with adult schistosomes in vitro demonstrated that the transcriptional level of Sj-riok-2 was affected by pairing. Knocking down Sj-riok-2 by RNAi reduced cell proliferation in the vitellarium and caused the increased amount of mature oocytes in ovary and an accumulation of eggs within the uterus. CONCLUSIONS: Sj-riok-2 is involved in the reproductive development and maturation of female S. japonicum. Our findings provide first evidence for a pairing-dependent role of Sj-riok-2 in the reproductive development and maturation of female S. japonicum. Thus this study contributes to the understanding of molecular processes controlling reproduction in schistosomes.

Molecular characterization of the Haemonchus contortus phosphoinositide-dependent protein kinase-1 gene (Hc-pdk-1).

BACKGROUND: Phosphoinositide-dependent protein kinase-1 (PDK-1), which functions downstream of phosphoinositide 3-kinase (AGE-1) and activates protein kinases of the AGC family, plays critical roles in regulating biology processes, such as metabolism, growth, development and survival. In the free-living nematode Caenorhabditis elegans, PDK-1 is a key component of the insulin-like signalling pathway, regulating the entry into and exit from dauer (arrested development). Although it is proposed that similar molecular mechanisms control the transition from the free-living to the parasitic stages of nematodes, nothing is known about PDK-1 in Haemonchus contortus, a socioeconomically important gastric nematode of ruminants. METHODS: Here, we isolated and characterized the pdk-1 gene (Hc-pdk-1) and its inferred product (Hc-PDK-1) from H. contortus. Using in vitro and in vivo methods, we then studied the transcriptional profiles of Hc-pdk-1 and anatomical gene expression patterns of Hc-PDK-1 in different developmental stages of C. elegans. RESULTS: In silico analysis of Hc-PDK-1 displayed conserved functional domains, such as protein kinase and pleckstrin homology (PH) domains and two predicted phosphorylation sites (Thr226/Tyr229), which are crucial for the phosphorylation of downstream signalling. The Hc-pdk-1 gene is transcribed in all of the main developmental stages of H. contortus, with its highest transcription in the infective third-stage larvae (iL3) compared with other stages. Transgene constructs, in which respective promoters were fused to the coding sequence for green fluorescent protein (GFP), were used to transform C. elegans, and to localize and compare the expression of Hc-pdk-1 and Ce-pdk-1. The expression of GFP under the control of the Hc-pdk-1 promoter was localized to the intestine, and head and tail neurons, contrasting somewhat the profile for the C. elegans ortholog, which is expressed in pharynx, intestine and head and tail neurons. CONCLUSIONS: This is the first characterization of pdk-1/PDK-1 from a trichostrongyloid nematode. Taken together, the findings from this study provide a first glimpse of the involvement of Hc-pdk-1 in the insulin-like signalling pathway in H. contortus.

Molecular cloning and characterization of Babesia orientalis rhoptry-associated protein 1.

The rhoptry-associated protein 1 (RAP-1) gene of Babesia orientalis was obtained from a cDNA expression library by immunoscreening with B. orientalis-infected water buffalo sera. The nucleotide sequence of the cDNA was 1732 bp with an open reading frame (ORF) of 1434 bp, encoding a polypeptide of 478 amino acid residues with a predicted size of 52.5 kDa. The ORF was cloned into a pGEX-KG plasmid and subsequently expressed as a GST-fusion protein. The recombinant RAP-1 of B. orientalis (rBoRAP-1) was purified and evaluated as an antigen using Western blotting. The native BoRAP-1 was recognized by the antibodies raised in rabbits against rBoRAP-1. Strong immunofluorescence signals were observed in erythrocytes infected with B. orientalis. Phylogentic analysis revealed that B. orientalis fell into a Babesia clade and most closely related to Babesia bovis and Babesia ovis, which was similar to the previous reported trees based on 18S rRNA and HSP70 genes. The present study suggests that the BoRAP-1 might be a potential diagnostic antigen, and the RAP-1 genes can aid in the classification of Babesia and Theileria species.

Toward understanding the functional role of Ss-RIOK-1, a RIO protein kinase-encoding gene of Strongyloides stercoralis.

BACKGROUND: Some studies of Saccharomyces cerevisiae and mammals have shown that RIO protein kinases (RIOKs) are involved in ribosome biogenesis, cell cycle progression and development. However, there is a paucity of information on their functions in parasitic nematodes. We aimed to investigate the function of RIOK-1 encoding gene from Strongyloides stercoralis, a nematode parasitizing humans and dogs. METHODOLOGY/PRINCIPAL FINDINGS: The RIOK-1 protein-encoding gene Ss-riok-1 was characterized from S. stercoralis. The full-length cDNA, gDNA and putative promoter region of Ss-riok-1 were isolated and sequenced. The cDNA comprises 1,828 bp, including a 377 bp 5'-UTR, a 17 bp 3'-UTR and a 1,434 bp ORF encoding a protein of 477 amino acids containing a RIOK-1 signature motif. The genomic sequence of the Ss-riok-1 coding region is 1,636 bp in length and has three exons and two introns. The putative promoter region comprises 4,280 bp and contains conserved promoter elements, including four CAAT boxes, 12 GATA boxes, eight E-boxes (CANNTG) and 38 TATA boxes. The Ss-riok-1 gene is transcribed throughout all developmental stages with the highest transcript abundance in the infective third-stage larva (iL3). Recombinant Ss-RIOK-1 is an active kinase, capable of both phosphorylation and auto-phosphorylation. Patterns of transcriptional reporter expression in transgenic S. stercoralis larvae indicated that Ss-RIOK-1 is expressed in neurons of the head, body and tail as well as in pharynx and hypodermis. CONCLUSIONS/SIGNIFICANCE: The characterization of the molecular and the temporal and spatial expression patterns of the encoding gene provide first clues as to functions of RIOKs in the biological processes of parasitic nematodes.

Molecular cloning and characterization of a novel heat shock protein 20 of Babesia orientalis.

The heat shock protein 20 (HSP20) gene of Babesia orientalis (BoHSP20) was identified from both genomic DNA and cDNA. The full-length BoHSP20 gene was 690bp with one intron from position 88-243bp. The amplicon obtained from cDNA corresponded to a full-length open reading frame (ORF) with a length of 534bp, encoding a polypeptide of 178 amino acid residues with a predicted size of 20kDa. The ORF was cloned into a pET-28a plasmid and subsequently expressed as a His-fusion protein. The recombinant HSP20 of B. orientalis (rBoHSP20) was purified and evaluated as an antigen using Western blotting. Anti-B. orientalis water buffalo serum reacted with rBoHSP20, indicating that this protein was an immunodominant antigen and could be a useful diagnostic reagent to detect antibodies against B. orientalis in water buffalo. The native BoHSP20 was recognized by polyclonal antibody from the serum of rabbit immunized with rBoHSP20. Strong immunofluorescence signals were observed from B. orientalis in blood smears by fluorescence microscopy. Bacterial survival experiments indicated that HSP20 can significantly increase the viability of bacteria when the culture is exposed to thermal stress. The results suggest that BoHSP20 might play an important role during B. orientalis transmission from tick to host animal, given the sudden shifts in temperature involved. Phylogenetic analysis revealed that B. orientalis is in the Babesia clade and most closely related to Babesia bovis. Similar topologies were obtained from trees based on 18S rRNA and the HSP70 gene. The present study suggests that BoHSP20 might be a potential diagnostic antigen and that the HSP20 genes can aid in the classification of Babesia and Theileria species.

Mitochondrial genome of Babesia orientalis, apicomplexan parasite of water buffalo (Bubalus babalis, Linnaeus, 1758) endemic in China.

BACKGROUND: Apicomplexan parasites of the genus Babesia, Theileria and Plasmodium are very closely related organisms. Interestingly, their mitochondrial (mt) genomes are highly divergent. Among Babesia, Babesia orientalis is a new species recently identified and specifically epidemic to the southern part of China, causing severe disease to water buffalo. However, no information on the mt genome of B. orientalis was available. METHODS: Four pairs of primers were designed based on the full genome sequence of B. orientalis (unpublished data) and by aligning reported mt genomes of B. bovis, B. bigemina, and T. parva. The entire mt genome was amplified by four sets of PCR. The obtained mt genome was annotated by aligning with published apicomplexan mt genomes and Artemis software v11. Phylogenetic analysis was performed by using cox1 and cob amino acid sequences. RESULTS: The complete mt genome of B. orientalis (Wuhan strain) was sequenced and characterized. The entire mt genome is 5996 bp in length with a linear form, containing three protein-coding genes including cytochrome c oxidase I (cox1), cytochrome b (cob) and cytochrome c oxidase III (cox3) and six rRNA large subunit gene fragments. The gene arrangement in B. orientalis mt genome is similar to those of B. bovis, B. gibsoni and Theileria parva, but different from those of T. orientalis, T. equi and Plasmodium falciparum. Comparative analysis indicated that cox1 and cob genes were more conserved than cox3. Phylogenetic analysis based on amino acid sequences of cox1, cob and cox1 + cob, respectively, revealed that B. orientalis fell into Babesia clade with the closest relationship to B. bovis. CONCLUSIONS: The availability of the entire mt genome sequences of B. orientalis provides valuable information for future phylogenetic, population genetics and molecular epidemiological studies of apicomplexan parasites.

Molecular epidemiology of Theileria annulata and identification of 18S rRNA gene and ITS regions sequences variants in apparently healthy buffaloes and cattle in Pakistan.

A molecular epidemiological survey was conducted to determine the prevalence of piroplasms in buffaloes and cattle from Sheikhupura and Okara districts of Punjab, Pakistan using reverse line blot (RLB) hybridization assay. The genetic diversity within 18S rRNA gene and ITS regions sequences of various obtained Theileria species (spp.) was also investigated. Briefly, 102 blood samples from buffaloes and cattle in the study districts were collected on blood collection cards and brought to the laboratory. DNA was extracted; the V4 hypervariable region of 18S rRNA was amplified and analyzed using RLB. Out of total samples analyzed, 61 (59.8%) were hybridized with Babesia/Theileria (B/T) genus-specific probe. Only one species of piroplasm was detected in buffaloes and cattle in study districts, i.e. Theileria (T.) annulata. Six samples only hybridized with B/T genus-specific and Theileria genus-specific probes but not with any species-specific probe indicating the presence of novel species or variants. The sequences of 18S rRNA gene and ITS regions of these six samples revealed the presence of T. annulata variants as confirmed through sequence identity estimation and phylogenetic analyses. Meanwhile, an unexpected sequence variation was observed within the 18S rRNA gene and ITS regions sequences of T. annulata identified in the present study. This is the first report on the simultaneous detection of species of piroplasms infecting buffaloes and cattle in Pakistan and molecular characterization of T. annulata 18S rRNA gene and ITS regions. The present study may address the new insights into the epidemiology of theileriosis which will help researches in designing control strategies and developing various molecular diagnostic tools at national level.

Detection and identification of Theileria infection in sika deer ( Cervus nippon ) in China.

The sika deer ( Cervus nippon ) is a first-grade state-protected animal in China and designated a threatened species by the World Conservation Union. To detect hemoparasite infection of sika deer, blood samples were collected from 24 animals in the Hubei Province Deer Center. Genomic DNA was extracted, and the V4 hypervariable region encoding 18S rRNA was analyzed by reverse line blot hybridization assay. PCR products hybridized with Babesia / Theileria genus-specific probes but failed to hybridize with any of the Babesia or Theileria species-specific probes, suggesting the presence of a novel, or variant, species. Here 18S rRNA and internal transcribed spacer (ITS) genes were amplified, cloned, and sequenced from 7 isolates. Alignment and BlastN of the cloned sequences revealed high similarities to the homologous 18S rRNA genes and ITS genes of Theileria cervi (AY735122), Theileria sp. CNY1A (AB012194), and Theileria sp. ex Yamaguchi (AF529272). Phylogenetic analysis based on the 18S rRNA gene and ITS sequences showed that all cloned sequences were grouped within the Theileria clade. Phylogeny based on the 18S rRNA gene divided the organisms into 2 groups. Group 1 was closest to Theileria sp. ex Yamaguchi (AF529272), and group 2 was distinct from all other identified Theileria and Babesia species. These results suggest the existence of Theileria sp. infection in sika deer in China. To our knowledge, this is the first report of cervine Theileria sp. in China.

Prevalence of coccidian infection in suckling piglets in China.

To determine the prevalence of coccidian infection in suckling piglets in China, fecal samples from 779 litters of suckling piglets were collected on 80 different farms in 17 provinces from September 2009 to December 2010. These samples were examined through saturated saline flotation technique. The prevalences of coccidian infection ranged from 0 to 32.5% among different provinces and the average was 16.7% (130/779). The highest prevalence of 19.9% (69/346) was found in 8-14 day-old litters of suckling piglets. Seven coccidian species were detected in the positive litters of suckling piglets, including Isospora suis (63.9%), Eimeria debliecki (46.9%), Eimeria polita (19.2%), Eimeria suis (20.8%), Eimeria perminuta (13.9%), Eimeria scabra (4.6%), and Eimeria yanglingensis (1.5%). 55.4% of the positive litters of suckling piglet infected more than one coccidian species. The results of this investigation will provide the relevant basic data for control strategies against porcine coccidiosis on pig farms in China.

Occurrence of Theileria and Babesia species in water buffalo (Bubalus babalis, Linnaeus, 1758) in the Hubei province, South China.

The presence and prevalence of tick-borne haemoparasites in water buffalo from the Hubei province, south China was investigated using the reverse line blot (RLB) hybridization assay and phylogenetic analysis of the parasite 18S rRNA gene. Theileria buffeli (19.1%) was the most frequently found species in all of the locations, followed by Babesia orientalis (8.9%), Babesia bovis (1.0%) and Babesia bigemina (0.7%). Only 12 (3.9%) of the samples had mixed infections. Eleven samples with single infections were selected for further characterization using 18S rRNA gene sequence analysis. Phylogenetic analysis showed that the eight T. buffeli 18S rRNA gene sequences obtained grouped into four clusters, of which three grouped with the known T. buffeli types B and D. The remaining five grouped separately from the previously describe T. buffeli types, constituting new T. buffeli types. The two B. bigemina 18S rRNA gene sequences obtained grouped closely with B. bigemina Kunming; this serves as the first report of B. bigemina in the Hubei province. The B. orientalis Daye 18S rRNA gene sequence obtained grouped closely with the previously reported B. orientalis Wuhan strain and with Babesia sp. Kashi 1 and Kashi 2.

Immunogenicity and protective efficacy of two recombinant pseudorabies viruses expressing Toxoplasma gondii SAG1 and MIC3 proteins.

Toxoplasma gondii is one of the most common parasitic pathogens in humans and warm-blooded animals, causing toxoplasmosis. One of the efficient ways to control this disease is immunization. In this study, two recombinant pseudorabies virus (PRV) expressing TgSAG1 (rPRV-SAG1) and TgMIC3 (rPRV-MIC3) based on the PRV vaccine strain were developed by homologous recombination and used for immunizing BALB/c mice. Ninety BALB/c mice were randomly divided into five groups including four experimental groups (inoculated twice in 4 weeks interval with PRV TK-/gG-/EGFP+, rPRV-SAG1, rPRV-MIC3, rPRV-SAG1+rPRV-MIC3, respectively) and one control group (inoculated with medium). All mice vaccinated with rPRV developed a high level of specific antibody responses against T. gondii lysate antigen (TLA), a strong increase of the splenocyte proliferative response, and significant levels of IFN-γ and IL-2 production. These results demonstrated that rPRV could induce significant humoral and cellular Th1 immune responses. Moreover, rPRV immunization induced partial protection against a lethal challenge with T. gondii RH strain, and neutralizing antibodies against PRV in a BALB/c mouse model. The mice immunized with the rPRV-SAG1 and rPRV-MIC3 cocktail could develop higher T. gondii-specific IgG antibodies and lymphocyte proliferative responses and conferred more efficient protection against T. gondii challenge. These results suggested that expression of protective antigens of T. gondii in PRV is a novel approach towards the development of a vaccine against both animal pseudorabies and toxoplasmosis.

Development and evaluation of real-time PCR assay for the detection of Babesia orientalis in water buffalo (Bubalus bubalis, Linnaeus, 1758).

Babesia orientalis is the causative agent of babesiosis in water buffalo (Bubalus babalis, Linnaeus, 1758). In this study, a TaqMan real-time PCR assay was developed for quantitative detection of B. orientalis in water buffalo. Hybridization probe and oligonucleotide primers were designed based on the v4 region of 18S rRNA gene. Detection limit was determined at 2 parasites. Blood samples were collected from experimentally infected water buffalo, as well as from 180 field samples, which were collected from 4 different geographical locations to the north and south of the Yangtse River. The parasite was detected by real-time PCR on day 2 until day 39 post-infection, while reverse line blot (RLB) was on day 6 until day 36 in experimentally infected water buffalo. For the results of 180 field samples, statistical analysis showed no significant difference in relative effectiveness of real-time PCR and RLB. The analysis also indicated that there was no difference in the prevalence of B. orientalis between the regions of south and north of the Yangtse River by both the real-time PCR assay and RLB detection. These results indicated that the parasite infection has spread to the north of the Yangtse River.

[Construction and immunoscreening of cDNA library of Babesia orientalis].

OBJECTIVE: To construct a cDNA library for Babesia orientalis and screen immunologically positive clones. METHODS: Total RNA of B. orientalis in red blood cells from an infected calf was isolated. cDNA was synthesized by reverse transcriptase, amplified by PCR and ligated into lambdaTriplEx2 vector. The recombined vectors were packaged and the unamplified cDNA library was constructed. The cDNA library was then amplified and immunologically screened with rabbit anti-B. orientalis serum. The recombinant lambdaTriplEx2 of positive clones were converted to the corresponding recombinant pTriplEx2. The inserted fragments were identified by PCR amplification. The plasmids were sequenced and compared against GenBank database by Blast. RESULTS: The titer of the unamplified library was 2.0 x 10(6) pfu/ml. The inserted fragment length of the library ranged from 500 to 3,000 bp, and the recombination efficiency accounted for 98.8%. The titer of the amplified library was 5.8 x 10(8) pfu/ml. Three positive clones were selected by serum immunological screening and named B04, B05, and B41, respectively. The inserted fragments of the B04, B05 and B41 were about 1,300 bp, 1,000 bp, and 2,400 bp, respectively. Sequence analysis revealed that the 3 clones contained open reading frames. Blast results showed that they were highly homologous to the nuclear movement protein gene, the hypothetical protein gene and the heat shock protein 70 (HSP70) gene, respectively. The deduced amino acid sequences of B04, B05 and B41 contained 310, 192 and 647 amino acid residues, with Mr of 34,000, 21,000, and 70,700, respectively. CONCLUSION: A qualified cDNA library of B. orientalis has been constructed and three positive clones of B. orientalis discovered.

Loop-mediated isothermal amplification (LAMP) detection of Babesia orientalis in water buffalo (Bubalus babalis, Linnaeus, 1758) in China.

Loop-mediated isothermal amplification (LAMP) is a rapid method with high specificity and efficiency under isothermal condition using a set of four specifically designed primers that recognize six distinct sequences on the target gene. In this study, a LAMP method was developed for specific detection of Babesia orientalis in water buffalo (Bubalus babalis, Linnaeus, 1758). Four primers were designed from the V4 hypervariable region of the 18S rRNA gene of B. orientalis. Blood samples were collected from B. orientalis experimentally infected water buffalo as well as from 165 water buffalo from eight different regions of the Hubei province, south China. Genomic DNA was extracted, subjected to the LAMP assay and compared with results obtained using a previously described semi-nested PCR. The LAMP assay proofed to be B. orientalis specific and more sensitive than the semi-nested PCR. While previously B. orientalis had not been reported north of the Yangtse River, our results show that B. orientalis has spread to the north of the river. This could pose a serious threat to the water buffalo industry.

Molecular cloning and phylogenetic analysis of Babesia orientalis heat shock protein 70.

The heat shock protein 70 (hsp70) gene of Babesia orientalis was obtained from a cDNA expression library by immunoscreening with B. orientalis infected buffalo sera. The nucleotide sequence of the cDNA was 2192bp with an open reading frame (ORF) of 1944bp encoding a polypeptide of 648 amino acid residues. Phylogenetic analysis of the 1944bp sequence together with 30 inter-erythrocytic protozoa hsp70 nucleotide sequences available from GenBank was performed. The results showed that B. orientalis was occurred within the Babesia clade, and most closely related to B. ovis and B. bovis. Similar topologies were obtained from trees based on apicomplexa parasite 18S rRNA sequence. Meanwhile, the BoHsp70 gene was cloned into pET-32a and subsequently expressed in Escherichia coli Rosetta strain as a Trx-fusion protein. The recombinant hsp70 of B. orientalis (rBoHsp70) was purified and evaluated as an antigen in the western blot. The serum from B. orientalis infected buffalo recognized the 92kDa rBoHsp70 expressed in E. coli Rosetta (DE3) by western blotting. The rabbit antiserum against rBoHsp70 recognized a specific 70kDa band in lysates of B. orientalis infected buffalo erythrocytes. These results suggested that hsp70 gene was well conserved among inter-erythrocytic protozoa and the BoHsp70 might be a diagnostic and candidate vaccine antigen.

Bis(ethyl-enediamine-κN,N')bis-(phenytoinato-κN)cobalt(II).

THE TITLE COMPOUND [SYSTEMATIC NAME: bis(2,5-dioxo-4,4-diphenylimidazolidin-1-ido-κN(1))bis(ethylenediamine-κ(2)N,N')cobalt(II)], [Co(C(15)H(11)N(2)O(2))(2)(C(2)H(8)N(2))(2)], has site symmetry . The Co(II) cation is located on an inversion center and coordinated by two phenytoin anions and two ethyl-enediamine ligands in a distorted octa-hedral geometry. In the phenytoin anion, the two phenyl rings are twisted with respect to the central hydantoin ring, making dihedral angles of 77.49 (16) and 64.55 (15)°. Intra-molecular and inter-molecular N-H⋯O hydrogen bonding is present in the crystal structure.