An innovative diagnostic technology for the codon mutation C580Y in kelch13 of Plasmodium falciparum with MinION nanopore sequencer.

BACKGROUND: The recent spread of artemisinin (ART)-resistant Plasmodium falciparum represents an emerging global threat to public health. In Southeast Asia, the C580Y mutation of kelch13 (k13) is the dominant mutation of ART-resistant P. falciparum. Therefore, a simple method for the detection of C580Y mutation is urgently needed to enable widespread routine surveillance in the field. The aim of this study is to develop a new diagnostic procedure for the C580Y mutation using loop-mediated isothermal amplification (LAMP) combined with the MinION nanopore sequencer. RESULTS: A LAMP assay for the k13 gene of P. falciparum to detect the C580Y mutation was successfully developed. The detection limit of this procedure was 10 copies of the reference plasmid harboring the k13 gene within 60 min. Thereafter, amplicon sequencing of the LAMP products using the MinION nanopore sequencer was performed to clarify the nucleotide sequences of the gene. The C580Y mutation was identified based on the sequence data collected from MinION reads 30 min after the start of sequencing. Further, clinical evaluation of the LAMP assay in 34 human blood samples collected from patients with P. falciparum malaria in Indonesia revealed a positive detection rate of 100%. All LAMP amplicons of up to 12 specimens were simultaneously sequenced using MinION. The results of sequencing were consistent with those of the conventional PCR and Sanger sequencing protocol. All procedures from DNA extraction to variant calling were completed within 3 h. The C580Y mutation was not found among these 34 P. falciparum isolates in Indonesia. CONCLUSIONS: An innovative method combining LAMP and MinION will enable simple, rapid, and high-sensitivity detection of the C580Y mutation of P. falciparum, even in resource-limited situations in developing countries.

Interactive transcriptome analysis of malaria patients and infecting Plasmodium falciparum.

To understand the molecular mechanisms of parasitism in vivo, it is essential to elucidate how the transcriptomes of the human hosts and the infecting parasites affect one another. Here we report the RNA-seq analysis of 116 Indonesian patients infected with the malaria parasite Plasmodium falciparum (Pf). We extracted RNAs from their peripheral blood as a mixture of host and parasite transcripts and mapped the RNA-seq tags to the human and Pf reference genomes to separate the respective tags. We were thus able to simultaneously analyze expression patterns in both humans and parasites. We identified human and parasite genes and pathways that correlated with various clinical data, which may serve as primary targets for drug developments. Of particular importance, we revealed characteristic expression changes in the human innate immune response pathway genes including TLR2 and TICAM2 that correlated with the severity of the malaria infection. We also found a group of transcription regulatory factors, JUND, for example, and signaling molecules, TNFAIP3, for example, that were strongly correlated in the expression patterns of humans and parasites. We also identified several genetic variations in important anti-malaria drug resistance-related genes. Furthermore, we identified the genetic variations which are potentially associated with severe malaria symptoms both in humans and parasites. The newly generated data should collectively lay a unique foundation for understanding variable behaviors of the field malaria parasites, which are far more complex than those observed under laboratory conditions.

A novel diagnostic method for malaria using loop-mediated isothermal amplification (LAMP) and MinION™ nanopore sequencer.

BACKGROUND: A simple and accurate molecular diagnostic method for malaria is urgently needed due to the limitations of conventional microscopic examination. In this study, we demonstrate a new diagnostic procedure for human malaria using loop mediated isothermal amplification (LAMP) and the MinION™ nanopore sequencer. METHODS: We generated specific LAMP primers targeting the 18S-rRNA gene of all five human Plasmodium species including two P. ovale subspecies (P. falciparum, P. vivax, P. ovale wallikeri, P. ovale curtisi, P. knowlesi and P. malariae) and examined human blood samples collected from 63 malaria patients in Indonesia. Additionally, we performed amplicon sequencing of our LAMP products using MinION™ nanopore sequencer to identify each Plasmodium species. RESULTS: Our LAMP method allowed amplification of all targeted 18S-rRNA genes of the reference plasmids with detection limits of 10-100 copies per reaction. Among the 63 clinical samples, 54 and 55 samples were positive by nested PCR and our LAMP method, respectively. Identification of the Plasmodium species by LAMP amplicon sequencing analysis using the MinION™ was consistent with the reference plasmid sequences and the results of nested PCR. CONCLUSIONS: Our diagnostic method combined with LAMP and MinION™ could become a simple and accurate tool for the identification of human Plasmodium species, even in resource-limited situations.

DB-AT: a 2015 update to the Full-parasites database brings a multitude of new transcriptomic data for apicomplexan parasites.

The previous release of our Full-parasites database (http://fullmal.hgc.jp/) brought enhanced functionality, an expanded full-length cDNA content, and new RNA-Seq datasets from several important apicomplexan parasites. The 2015 update witnesses the major shift in the databases content with focus on diverse transcriptomes of the apicomplexan parasites. The content of the database was substantially enriched with transcriptome information for new apicomplexan parasites. The latest version covers a total of 17 species, with addition of our newly generated RNA-Seq data of a total of 909,150,388 tags. Moreover, we have generated and included two novel and unique datasets, which represent diverse nature of transcriptomes in individual parasites in vivo and in vitro. One is the data collected from 116 Indonesian patients infected with Plasmodium falciparum. The other is a series of transcriptome data collected from a total of 38 single cells of P. falciparum cultured in vitro. We believe that with the recent advances our database becomes an even better resource and a unique platform in the analysis of apicomplexan parasites and their interaction with their hosts. To adequately reflect the recent modifications and the current content we have changed the database name to DB-AT--DataBase of Apicomplexa Transcriptomes.

Coelacanth genomes reveal signatures for evolutionary transition from water to land.

Coelacanths are known as "living fossils," as they show remarkable morphological resemblance to the fossil record and belong to the most primitive lineage of living Sarcopterygii (lobe-finned fishes and tetrapods). Coelacanths may be key to elucidating the tempo and mode of evolution from fish to tetrapods. Here, we report the genome sequences of five coelacanths, including four Latimeria chalumnae individuals (three specimens from Tanzania and one from Comoros) and one L. menadoensis individual from Indonesia. These sequences cover two African breeding populations and two known extant coelacanth species. The genome is ∼2.74 Gbp and contains a high proportion (∼60%) of repetitive elements. The genetic diversity among the individuals was extremely low, suggesting a small population size and/or a slow rate of evolution. We found a substantial number of genes that encode olfactory and pheromone receptors with features characteristic of tetrapod receptors for the detection of airborne ligands. We also found that limb enhancers of bmp7 and gli3, both of which are essential for limb formation, are conserved between coelacanth and tetrapods, but not ray-finned fishes. We expect that some tetrapod-like genes may have existed early in the evolution of primitive Sarcopterygii and were later co-opted to adapt to terrestrial environments. These coelacanth genomes will provide a cornerstone for studies to elucidate how ancestral aquatic vertebrates evolved into terrestrial animals.

Molecular detection and identification of Babesia bovis and Babesia bigemina in cattle in northern Thailand.

Although Babesia bovis and Babesia bigemina infections cause economic losses in the cattle industry in northern Thailand, there is inadequate information on Babesia isolates present in the area. Therefore, to determine the prevalence and genetic relationship between Babesia isolates, we screened 200 blood samples of cattle from Chiang Rai, Chiang Mai, and Lumpang provinces of northern Thailand. A nested polymerase chain reaction using primers targeting B. bovis spherical body protein 2 (BboSBP2) and B. bigemina rhoptry-associated protein 1a (BbiRAP-1a) genes revealed a prevalence of 12 and 21 % for B. bovis and B. bigemina, respectively, while that of mixed infections was 6.5 % samples. The prevalences of B. bovis in Chiang Rai, Chiang Mai, and Lumpang were 9.5, 3.7, and 25.5 %, respectively. For B. bigemina, the prevalences were 15.8, 12.9, and 39.2 % in Chiang Rai, Chiang Mai, and Lumpang, respectively. Mixed infections with B. bovis and B. bigemina were 6.3 % in Chiang Rai, 1.9 % in Chiang Mai, and 13.7 % in Lumpang. The identical sequences of either BboSBP2 gene or BbiRAP-1a gene were shared among the Babesia isolates in the three provinces of northern Thailand. Further analysis using the internal transcribed spacer gene revealed at least four genotypes for B. bovis and five genotypes for B. bigemina in northern Thailand, while the sequences present great genetic diversities in the different isolates. Overall, we have demonstrated a high prevalence and polymorphism of Babesia parasites in northern Thailand calling for the need to design effective control programs for bovine babesiosis.

Global research alliance in infectious disease: a collaborative effort to combat infectious diseases through dissemination of portable sequencing.

OBJECTIVE: To disseminate the portable sequencer MinION in developing countries for the main purpose of battling infectious diseases, we found a consortium called Global Research Alliance in Infectious Diseases (GRAID). By holding and inviting researchers both from developed and developing countries, we aim to train the participants with MinION's operations and foster a collaboration in infectious diseases researches. As a real-life example in which resources are limited, we describe here a result from a training course, a metagenomics analysis from two blood samples collected from a routine cattle surveillance in Kulan Progo District, Yogyakarta Province, Indonesia in 2019. RESULTS: One of the samples was successfully sequenced with enough sequencing yield for further analysis. After depleting the reads mapped to host DNA, the remaining reads were shown to map to Theileria orientalis using BLAST and OneCodex. Although the reads were also mapped to Clostridium botulinum, those were found to be artifacts derived from the cow genome. An effort to construct a consensus sequence was successful using a reference-based approach with Pomoxis. Hence, we concluded that the asymptomatic cow might be infected with T. orientalis and showed the usefulness of sequencing technology, specifically the MinION platform, in a developing country.

Salivary IgA as a useful non-invasive marker for restraint stress in pigs.

In this study, we investigated the expression of immunoglobulin A (IgA) in porcine salivary gland and its relationship with restraint stress in pigs. IgA was expressed in plasma cells in pig salivary gland, as confirmed by immunohistochemical staining. IgA was also detected in pig saliva itself by ELISA, and salivary IgA levels were increased by a restraint stress. Moreover, there was a circadian rhythm of IgA over the course of a day. These results are the first evidence of IgA expression related to stress in the pig saliva and may make IgA useful as a non-invasive biological marker to evaluate acute stress condition in the pigs.

Computed tomography (CT) observation of pulmonary emboli caused by long-term administration of ivermectin in dogs experimentally infected with heartworms.

Some studies have reported the adulticidal effect of long-term ivermectin (IVM) administration on adult heartworms in canines; however, there are no detailed reports on the course of the pulmonary artery embolism caused by the bodies of dead heartworms during the administration period. In this study, the pulmonary embolism caused over time by the dead worms was observed using computed tomography (CT). We subcutaneously inoculated 2 beagles with 100 infective third-stage larvae (L3) of Dirofilaria immitis. The dogs were orally administered a formulation containing 272 microg of IVM and 652 mg of pyrantel pamoate (Panamectin Chewables P272; Meiji Seika, Tokyo, Japan) at monthly intervals, beginning from 10 months after the subcutaneous inoculation. Along with IVM administration, periodic CT examination of the chest was performed. At 15 months after the initiation of IVM administration, the dogs were euthanized, the living heartworms were collected, and histopathological examination was performed. Starting from 1 month after the IVM administration, peripheral dilation of the pulmonary artery (suspected to be pulmonary embolism) and pneumonia were observed in the CT images; however, these findings improved over time. The appearance and disappearance of these lesions were observed in all the lobes during the IVM administration period. During this period, the clinical symptoms of pulmonary embolism were not recognized. After 1 month of IVM administration, chest radiographic examination revealed radiopaque lesions in 1 dog. Only some of the lesions detected by CT could be detected by radiography. Using echocardiography, heartworms were observed in the pulmonary arteries of both dogs from 6 months after subcutaneous inoculation to the end of the study period. Microfilaria disappeared from the peripheral blood at 1 month after IVM administration in 1 dog, and at 7 months in the other dog. The adult heartworm antigen test yielded positive results starting from 6 months after subcutaneous inoculation in 1 dog and after 7 months in the other dog; these results remained positive until the end of the study period. After the initiation of IVM administration, the ALP and CK levels were transiently elevated. The number of surviving adult worms collected at necropsy was 25 in 1 dog and 31 in the other. Histopathological examination revealed that the peripheral pulmonary artery dilation detected by CT was the embolus that resulted from the bodies of the dead heartworms. Moreover, vessel recanalization and inflammation along with lymphocyte infiltration around the vessels was observed. These results revealed that long-term IVM administration has a gradual adulticidal effect on heartworms in canines and embolism. From recovery findings showed pulmonary embolism in the CT image and histopathologic examination, long-term IVM administration can potentially be used for adulticidal treatment in clinical cases where it is difficult to perform surgical extirpation and administer arsenic therapy.

Nanopore sequencing of drug-resistance-associated genes in malaria parasites, Plasmodium falciparum.

Here, we report the application of a portable sequencer, MinION, for genotyping the malaria parasite Plasmodium falciparum. In the present study, an amplicon mixture of nine representative genes causing resistance to anti-malaria drugs is diagnosed. First, we developed the procedure for four laboratory strains (3D7, Dd2, 7G8, and K1), and then applied the developed procedure to ten clinical samples. We sequenced and re-sequenced the samples using the obsolete flow cell R7.3 and the most recent flow cell R9.4. Although the average base-call accuracy of the MinION sequencer was 74.3%, performing >50 reads at a given position improves the accuracy of the SNP call, yielding a precision and recall rate of 0.92 and 0.8, respectively, with flow cell R7.3. These numbers increased significantly with flow cell R9.4, in which the precision and recall are 1 and 0.97, respectively. Based on the SNP information, the drug resistance status in ten clinical samples was inferred. We also analyzed K13 gene mutations from 54 additional clinical samples as a proof of concept. We found that a novel amino-acid changing variation is dominant in this area. In addition, we performed a small population-based analysis using 3 and 5 cases (K13) and 10 and 5 cases (PfCRT) from Thailand and Vietnam, respectively. We identified distinct genotypes from the respective regions. This approach will change the standard methodology for the sequencing diagnosis of malaria parasites, especially in developing countries.

Possibility of Neospora caninum infection by venereal transmission in CB-17 scid mice.

CB-17 scid and BALB/c male mice were inoculated intraperitoneally with Neospora caninum to examine the possibility of its venereal transmission. Some of these mice were killed on days 7 and 20 post-inoculation to examine the genital organs for presence of the parasite. The remaining scid male mice were housed with non-infected female mice from day 7 p.i. and kept with them for 14 days. These scid mice died between days 28 and 35 p.i. N. caninum DNA was detected in the testis of mice on days 7 and 20 p.i. by PCR and tachyzoite viability was determined by bioassay conducted by means of mouse inoculation. Microscopically, fewer tachyzoites were detected in the testis obtained on day 20 p.i., than in other organs. The inoculated BALB/c male mice survived until the end of the experiment with no clinical signs and N. caninum DNA was detected in the testis on day 7 p.i. but not on day 14 p.i. Five of eight female scid mice housed with infected males became pregnant. Tachyzoites were detected in three of these mice and their neonates (n=3, 5 and 13, respectively). In three non-pregnant mice, no parasite was detected. Two of the four female BALB/c mice housed with infected male scid mice became pregnant but the parasite was not detected in them or in the neonates (n=3 and 13, respectively). These results indicate that the tachyzoites were present in the genital organs of the immunodeficient mice from day 7 p.i. and suggest that transmission may occur through mating with male mice.

C57BL/6 mice infected with Neospora caninum during administration of progesterone show bias toward type 2 immune response.

To clarify the role of progesterone in the development of immune responses during pregnancy against Neospora caninum infection, C57BL/6 mice were given a progesterone pellet, and measured on Interferon-gamma and interleukin-4 production following the infection. IFN-gamma production in the prescribed group was significantly lower than that in the intact group on day 40 post administration. IL-4 producing cell population in the prescribed group was larger than that in the intact group. These results suggest that progesterone may alter the balance of cytokine production, and that the bias toward type 2 immune response may remain for a certain period after the infection.

Genetic polymorphisms in Plasmodium falciparum chloroquine resistance genes, pfcrt and pfmdr1, in North Sulawesi, Indonesia.

BACKGROUND: Malaria still poses one of the major threats to human health. Development of effective antimalarial drugs has decreased this threat; however, the emergence of drug-resistant Plasmodium falciparum, a cause of Malaria, is disconcerting. The antimalarial drug chloroquine has been effectively used, but resistant parasites have spread worldwide. Interestingly, the withdrawal of the drug reportedly leads to an increased population of susceptible parasites in some cases. We examined the prevalence of genomic polymorphisms in a malaria parasite P. falciparum, associated with resistance to an antimalarial drug chloroquine, after the withdrawal of the drug from Indonesia. RESULTS: Blood samples were collected from 95 malaria patients in North Sulawesi, Indonesia, in 2010. Parasite DNA was extracted and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for pfcrt and pfmdr1. In parallel, multiplex amplicon sequencing for the same genes was carried out with Illumina MiSeq. Of the 59 cases diagnosed as P. falciparum infection by microscopy, PCR-RFLP analysis clearly identified the genotype 76T in pfcrt in 44 cases. Sequencing analysis validated the identified genotypes in the 44 cases and demonstrated that the haplotype in the surrounding genomic region was exclusively SVMNT. Results of pfmdr1 were successfully obtained for 51 samples, where the genotyping results obtained by the two methods were completely consistent. In pfmdr1, the 86Y mutant genotype was observed in 45 cases (88.2%). CONCLUSIONS: Our results suggest that the prevalence of the mutated genotypes remained dominant even 6 years after the withdrawal of chloroquine from this region. Diversified haplotype of the resistance-related locus, potentially involved in fitness costs, unauthorized usage of chloroquine, and/or a short post-withdrawal period may account for the observed high persistence of prevalence.

Prevalence of Toxoplasma gondii and Neospora caninum in sika deer from eastern Hokkaido, Japan.

Brain and serum were collected from 120 and 12 free-ranging sika deer (Cervus nippon yesoensis), respectively, from six regions in eastern Hokkaido during controlled hunts in the autumn of 2003. Brains were tested for Neospora caninum and Toxoplasma gondii DNA by polymerase chain reaction (PCR) assays. Antibodies to Toxoplasma gondii were measured by means of a latex agglutination test. No brain tested positive for either type of DNA, and no antibody to Toxoplasma gondii was detected in serum, suggesting a low prevalence of infection with these organisms in free-ranging sika deer from eastern Hokkaido. Further examination of multiple tissues by PCR and serologic surveys will be necessary to confirm this.