Parasites, hosts and diseases最新文献

Toxoplasma gondii is an intracellular protozoan parasite capable of causing chronic infection by forming persistent cysts in the brain. Despite its global burden, no approved vaccine exists. Virus-like particle vaccines expressing microneme protein 8 (MIC8) or apical membrane antigen 1 (AMA1) of T. gondii have previously shown efficacy. In this study, we generated recombinant vaccinia viruses (rVVs) expressing MIC8 and AMA1 and evaluated their efficacy against T. gondii ME49 infection. BALB/c mice were intramuscularly immunized with a combination of MIC8 and AMA1 rVVs and challenged orally with T. gondii ME49. Immunization with MIC8+AMA1 rVVs produced a significant increase in T. gondii-specific IgG. Splenocyte analysis revealed robust activation of CD4+ and CD8+ T cells, as well as expansion of memory B cells. The immunized group exhibited an 89.6% reduction in brain cyst count, with significantly improved survival compared to the control group. These findings demonstrate that combining the antigens MIC8 and AMA1 using a vaccinia virus platform can effectively promote both humoral and cellular immunity, supporting its potential as a vaccine strategy against T. gondii ME49.

Caryophyllaeus brachycollis mainly parasitizes the intestines of globally distributed freshwater fishes, and infection causes significant economic losses to the aquaculture industry. However, data on the molecular epidemiology, population genetics, and systematics of C. brachycollis are scarce. In this study, we sequenced the complete mitogenome of C. brachycollis isolated from Beijing, China. This circular mitogenome comprised 14,273 bp, which was 231 bp shorter than that of C. brachycollis isolated from Wuhan, China. The mitogenome contained 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 2 noncoding regions. Bayesian inference revealed that C. brachycollis belonged to the family Caryophyllaeidae. The taxonomic status of C. brachycollis is controversial when based solely on morphological features. A comparative analysis of the mitogenome sequence obtained in this study revealed novel molecular markers for the accurate ascertainment of the phylogenetic position of this parasite.

The leopard cat (Prionailurus bengalensis) is a wild felid species that serves as a reservoir of zoonotic parasites. In this study, we investigated intestinal parasite taxa by reanalyzing previously published shotgun metagenomic sequencing data from fecal samples of wild leopard cats using a custom 18S rRNA gene reference database constructed from the NCBI nucleotide database. Among 11 metagenomic samples, 5 parasite species were identified: Toxoplasma gondii, Clonorchis sinensis, Strongyloides planiceps, Cylicospirura petrowi, and Pharyngostomum cordatum. These findings demonstrate that shotgun metagenomic analysis of fecal samples can be a useful tool for monitoring zoonotic parasite infections in this species and for investigating parasite life cycles. However, this approach is limited by its dependence on existing reference databases and requires experimental validation of the findings.

We present a nearly complete mitochondrial genome (mitogenome) of Hymenolepis diminuta from a Danish isolate, which was reassembled and comprehensively annotated using whole-genome sequencing data retrieved from the Sequence Read Archive (accession No. ERS056110). Although 2 mitogenomes of H. diminuta have previously been submitted to GenBank (accession No. AP017664, Danish isolate; NC_002767, putative German laboratory strain), the former lacks noncoding regions, while the latter harbors relatively short repeat units. Our newly reconstructed mitogenome is 14,090 bp long, comprising 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a 643-bp noncoding region containing 7 tandem repeat units. The annotated sequence has been deposited in the Third Party Annotation database in GenBank (accession No. BK071817). Phylogenetic analysis based on mitogenomic sequences confirmed a close relationship between H. diminuta and Hymenolepis nana. This improved mitogenome sequence represents a valuable resource for comparative mitogenomic and phylogenetic investigations within the families Hymenolepididae, Taeniidae, and Diphyllobothriidae.

Adult notocotylid flukes (Digenea: Notocotylidae) were recovered from the ceca of Pitalah ducks (Anas sp.) in Aceh Province, Indonesia. These flukes were morphologically characterized by a median ventral ridge with 2 lateral rows of ventral papillae and the absence of both a ventral sucker and pharynx, consistent with the characteristics of the genus Catatropis. They exhibited a genital pore located just posterior to the oral sucker, 10-11 pairs of ventral papillae, a deep and multi-lobed ovary and testes, a metraterm equal in length to the cirrus sac, and ceca bearing numerous diverticula; accordingly, they were identified as Catatropis indicus Srivastava, 1935. Adult specimens measured 3.01-3.77 mm (average 3.47 mm) in length and 0.98-1.21 mm (average 1.11 mm) in width (n=8). Uterine eggs measured 0.016-0.023 mm (average 0.019 mm) in length and 0.008-0.014 mm (average 0.012 mm) in width (n=20), each bearing 2 long polar filaments. These specimens resembled Catatropis vietnamensis Izrailskaia et al., 2019, and Catatropis pakistanensis Schuster and Wibbelt, 2012, sharing features such as a genital pore immediately posterior to the oral sucker and other morphological traits. However, they differed from C. vietnamensis by having a larger body, ceca with numerous diverticula, and a broader anterior distribution of vitelline follicles. They also differed from C. pakistanensis in possessing a longer esophagus and ceca with multiple diverticula. In 28S rDNA sequence analysis, our specimens showed 99.1% identity with both C. indicus and C. vietnamensis. In contrast, internal transcribed spacer 2 (ITS2) sequence comparisons revealed only 96.0%-96.1% identity with C. vietnamensis (no GenBank data available for C. indicus), suggesting that our specimens are phylogenetically distant from C. vietnamensis. This represents the first report of C. indicus from ducks in Indonesia. A brief review of Catatropis species is provided.

Cysteine proteases play key roles in the biology of Plasmodium parasites and are recognized as antimalarial drug targets. Because these enzymes are involved in diverse biological functions, precise regulation is required to prevent unnecessary damage to both parasites and hosts. In this study, we identified an endogenous inhibitor of cysteine protease of Plasmodium vivax (PvICP) and characterized its biochemical properties. PvICP was found to share highly similar structural characteristics with orthologous proteins from other Plasmodium species. Recombinant PvICP (rPvICP) expressed in Escherichia coli showed a broad range of inhibitory activity against falcipain family cysteine proteases, including vivapain-3, vivapain-4, falcipain-3, malapain-2, and malapain-4, with more potent inhibitory activity against vivapain-3 and vivapain-4. rPvICP's inhibitory activity was not significantly affected by pH, suggesting its broad biological functions. These findings provide new insights into PvICP and lay the groundwork for future studies exploring its biological significance and potential as a therapeutic target in malaria research.

Alpacas (Vicugna pacos), native to South America, were recently introduced to Korea, primarily for tourism-related activities. However, information on their parasitic infections in alpacas within the region are limited. This study aimed to investigate the longitudinal prevalence and diversity of gastrointestinal parasites in an alpaca herd on a single farm in Korea and to assess the potential risks for reinfection and interspecies transmission. Between June 2022 and June 2023 (excluding December 2022 and January 2023), fecal samples were collected monthly from a herd of 61 alpacas housed on a farm on Jeju Island, Korea. Coprological examination of 406 samples was performed using a modified McMaster technique, and parasites were identified morphologically. Six gastrointestinal parasite taxa were identified: strongyles, Trichuris sp., capillarids, Moniezia sp., Eimeria lamae, and Eimeria macusaniensis. The overall gastrointestinal parasite prevalence was 11.3%, with strongyles and Trichuris sp. most frequently identified. No seasonal trends were observed, and mixed infections were present in five animals. The prevalence was markedly lower compared with reports from Japan, Poland, and Australia, reflecting the restricted pasture access implemented by Korea's alpaca management systems, which are primarily tourism-oriented. Neither Nematodirus spp. nor zoonotic parasites were detected. This is the first longitudinal investigation of gastrointestinal parasites in alpacas in Korea. Although the overall prevalence was low, environmental contamination and the risk of reinfection are ongoing concerns. These findings highlight the need for routine surveillance, targeted parasite control, and consistent veterinary oversight, particularly as alpaca populations expand in Korea.

Balamuthia mandrillaris is a causative agent of granulomatous amebic encephalitis, a rare but often fatal condition. To investigate the role of T helper (Th) cell subsets in the immune response against B. mandrillaris, we examined 3 mouse strains with distinct immunological profiles: C57BL/6 (Th1-dominant), BALB/c (Th2-dominant), and ICR (balanced Th1/Th2). Mice were infected intranasally with 1×105 amoebae. Body weight and neurologic symtoms were monitored weekly, and cytokine expression was assessed biweekly over 6 weeks. Minimal weight loss and no mortality were observed in C57BL/6 mice, whereas BALB/c and ICR mice exhibited significant early and delayed mortality, respectively. Interleukin-17A expression was notably elevated in C57BL/6 mice compared with the other strains. These findings indicate that a robust Th17 response, particularly interleukin-17A production, is a critical component of the host defense against B. mandrillaris infection.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive genetic disorder that can cause severe anemia in affected individuals exposed to oxidative stress. This risk is particularly relevant in patients treated with the antimalarial drug primaquine. In Myanmar, primaquine has been widely administered as a Plasmodium vivax malaria treatment; however, prevalence of G6PD deficiency among the population remains insufficiently characterized. This study investigated the prevalence of G6PD variants among various minority ethnic subgroups residing in Kachin State, Myanmar. Blood samples from 440 participants were analyzed; however, the Mahidol variant (G487A) was identified in 21 individuals (4.8%). A major limitation of this study was the absence of G6PD enzyme activity data to confirm whether the Mahidol variant induces G6PD deficiency.