Parasites, hosts and diseases最新文献

Intraflagellar transport (IFT) particles, a multi-protein apparatus composed of complex A and B, are known to be involved in homeostasis of flagella formation. IFT particles have recently become an interesting topic in Giardia lamblia, which has 4 pairs of flagella. In this experiment, we examined the function of giardial IFT components. When 7 components (IFT121, 140, 20, 46, 52, 81, and 88) of IFT were expressed in Giardia trophozoites as a tagged form with mNeonGreen, all of them were found in both flagella pores and cytoplasmic axonemes. In addition, motor proteins for IFT particles (kinesin-13 and kinesin-2b), were localized to a median body and cytoplasmic flagella, respectively. The CRISPRi-mediated knockdown of IFT88 significantly affected the lengths of all 4 flagella compared to the control cells, Giardia expressing dead Cas9 using control guide RNA. Decreased expression of kinesin-2b also resulted in shortening of flagella, excluding the ventral flagella. Live Giardia cells expressing IFT88-mNeonGreen clearly demonstrated fluorescence in flagella pores and cytoplasmic axonemes. These results on IFT88 and kinesin-2b indicate that IFT complex plays a role in maintenance of G. lamblia flagella.

Cancer immunotherapy is widely used to treat various cancers to augment the weakened host immune response against tumors. Dendritic cells (DCs) are specialized antigen-presenting cells that play dual roles in inducing innate and adaptive immunity. Toxoplasma gondii is a protozoan parasite that exhibits anti-tumor activity against certain types of cancers. However, little is known about the anti-tumor effects of T. gondii or tumor/parasite antigen-pulsed DCs (DC vaccines, DCV) in breast cancer. In this study, C57BL/6 mice were administered E0771 mouse breast cancer cells (Cancer-injected) subcutaneously, T. gondii Me49 cysts orally (TG-injected), or DCs pulsed with breast cancer cell lysate antigen and T. gondii lysate antigens (DCV-injected) intraperitoneally. Tumor size and immunological characteristics were subsequently evaluated. We also evaluated matrix metalloproteinase (MMP)-2 and MMP-9 levels in E0771 mouse breast cancer cells co-cultured with T. gondii or DCs by RT-PCR. The tumor volumes of mice injected with breast cancer cells and antigen-pulsed DCs (Cancer/DCV-injected mice) were similar to those of Cancer-injected mice; however, they were significantly reduced in T. gondii-infected tumor-bearing (TG/Cancer-injected) mice. Moreover, tumor volumes were significantly reduced by adding antigen-pulsed DCs (TG/Cancer/DCV-injected mice) compared to TG/Cancer-injected mice. The levels of IFN-γ, serum IgG2a levels, and CD8+ T cell populations were significantly higher in DCV- and TG-injected mice than in control mice, while no significant differences between Cancer- and Cancer/DCV-injected mice were observed. The levels of IFN-γ, the IgG2a levels, and the percentage of CD8+ T cells were significantly increased in TG/Cancer- and TG/Cancer/DCV-injected mice than in Cancer-injected mice. IFN-γ levels and serum IgG2a levels were further increased in TG/Cancer/DCV-injected mice than in TG/Cancer-injected mice. The MMP-2 and MMP-9 mRNA expressions were significantly decreased in mouse breast cancer cells co-cultured with live T. gondii, T. gondii lysate antigen, or antigen-pulsed DCs (DCV) but not in inactivated DCs. These results indicate that T. gondii induces anti-tumor effects in breast cancer-bearing mice through the induction of strong Th1 immune responses, but not in antigen-pulsed DCs alone. The addition of antigen-pulsed DCs further augments the anti-tumor effects of T. gondii.

We identified the presence of Toxoplasma gondii in ticks and their host dogs, and assess the potential role of ticks as reservoirs for this pathogen. A total of 1,230 feeding ticks were collected from 340 dogs. The tick species identified included Haemaphysalis longicornis, H. flava, and Ixodes nipponensis. Detection of the T. gondii B1 gene occurred in 2 dogs (0.6%) and 4 tick pools (0.9%). Genotyping confirmed the presence of the I/III genotype. This study is the first to report the molecular detection of T. gondii in both canine ticks and their hosts. Our findings offer important insights into the dynamics of T. gondii transmission between vectors and their hosts.

As many countries implement different programs aimed at eliminating malaria, attention should be given to asymptomatic carriers that may interrupt the progress. This was a community-based cross-sectional study conducted in Tanzania from December 2022 to July 2023 within 4 villages from each of the 3 regions, Geita and Kigoma, which are high malaria transmission, and Arusha, which is low transmission. Malaria was diagnosed in asymptomatic individuals aged 1 year and older using the malaria rapid diagnostic test and light microscope. A total of 2,365 of 3,489 (67.9%) participants were enrolled from high-transmission villages. The overall prevalence was 25.5% and 15.8% by malaria rapid diagnostic test and light microscope, respectively. Using the respective tools, the prevalence was significantly higher at 35.6% (confidence interval (CI)=23.6-49.9) and 23.1% (CI=16.2-35.1) in the high-transmission regions (Geita and Kigoma) compared with 2.9% (CI=1.1-3.5) and 1.1% (CI=0.7-1.8) in the low-transmission region (Arusha). Children younger than 15 years and males accounted for the greatest proportion of infections. In the study area, the prevalence of asymptomatic cases was higher than that of reported symptomatic cases in health facilities. We hypothesize that these parasite reservoirs may contribute to the persistence of malaria in the country. Therefore, to achieve comprehensive malaria control in the country, the surveillance and screening of asymptomatic malaria cases are vital.

Toxoplasma gondii primarily invades the central nervous system, causing latent infections. Cysts persist in the host for life and there is currently no effective treatment. T. gondii infects human hosts through contaminated meat, invading the intestinal tissue and leading to changes in the number and composition of the gut microbiota. Since probiotic ingestion modulates intestinal microbiota changes, we hypothesized that intestinal microbiota dysbiosis caused by T. gondii infection would be restored following probiotic supplementation. To this end, we orally infected C57BL/6 mice with 10 T. gondii cysts and administered supplemental probiotics daily. We analyzed the levels of T. gondii B1 gene DNA, indicative of T. gondii infection, in brain tissue. We investigated alterations in the gut microbiota composition and functional pathways between the probiotic and non-probiotic treatment groups via next-generation sequencing analysis of each fecal sample. The infection level in the probiotic-treated group was significantly reduced after 4 weeks (p<0.05). Probiotic supplementation notably changed the gut microbiota after 2 weeks of infection, increasing the relative abundance of Intestinimonas massiliensis and Lawsonibacter asaccharolyticus. Probiotic supplements appear to modulate the gut microbiota, activating functional pathways involved in intestinal short-chain fatty acid production and strengthening the intestinal barrier, thereby impeding T. gondii infection and subsequent proliferation. Our findings provide valuable insights into T. gondii infection control and future study directions.

This study was conducted to examine the pathogenesis of gill degeneration in the Korean rockfish Sebastes schlegelii, infested with the monogenean ectoparasite, Microcotyle sebastis. We collected 30 Korean rockfish from a fish farm in Tongyeong-si, Gyeongsangnam-do, and examined them with light microscopy, scanning electron microscopy (SEM), and histopathology, in March 2018. The monogenean trematode, M. sebastis, was detected in 27 Korean rockfish (90%), with the intensity of infection being 31.7 per fish. The characteristic surface ultrastructures such as tegument with transverse striations, genital atrium, genital pore, and opisthaptor with numerous clamps were observed. The worms were firmly attached to the gill lamellae using clamps from the opisthaptor, causing gill damage and degeneration. The distal part of the lamellae was ruptured by the sclerites of the clamps. The histopathological examination revealed epithelial hypertrophy, hyperplasia, and occasionally fusion of the lamellae. These ultrastructural and histopathological findings provide some understanding of the pathogenesis of gill degeneration in the Korean rockfish infested with M. sebastis.

Naegleria fowleri, a brain-eating amoeba, thrives in lakes and rivers with aquatic vegetation and causes primary amoebic meningoencephalitis (PAM) in humans. Most recently, it has become such a serious problem that N. fowleri was detected in tap water in Houston, USA. Several pathogenic factors are considered very important to destroy target cells in the brain. In particular, the food-cup where N. fowleri antigen-1 (Nfa1) is located, is strongly expressed in pseudopodia involved in the movement of N. fowleri, and is involved in phagocytosis by attaching to target cells. In this article, we reviewed the role of the Nfa1 protein and its associated pathogenicity. The nfa1 gene was cloned by cDNA library immunoscreening using infection serum and immune serum. Nfa1 protein is mainly distributed in pseudopodia important to movement and vacuoles. Moreover, heat shock protein 70, cathepsin-like proteare and Nf-actin are also associated with pseudopodia in which Nfa1 is localized. Interestingly, the amount of the nfa1 gene changed as N. fowleri trophozoites transformed into cysts. Polyclonal antiserum against Nfa1 showed a protective effect against cytotoxicity of approximately 19.7%. Nfa1-specific IgA antibodies prevent N. fowleri trophozoites from adhering to the nasal mucosa, delaying invasion. The nfa1-vaccinated mice showed significantly higher levels of Nfa1-specific antibody. The duration of anti-Nfa1 IgG in the vaccinated mice lasted 12 weeks, strongly suggesting that nfa1 is a significant pathogenic gene and that Nfa1 is a pathogenic protein. Several factors related to pseudopodia and locomotion have been linked to Nfa1. A clearer function of N. fowleri targeting nfa1 with other genes might enable target-based inhibition of N. fowleri pathogenicity.

Clonorchis sinensis, which causes clonorchiasis, is prevalent in East Asian countries and poses notable health risks, including bile duct complications. Although praziquantel is the primary treatment for the disease, the emerging resistance among trematodes highlights the need for alternative strategies. Understanding the nutrient uptake mechanisms in trematodes, including C. sinensis, is crucial for developing future effective treatments. This study aimed to characterize the function of C. sinensis glucose transporter 4 (CsGTP4) and determine its role in nutrient uptake employing synthesized cDNA of adult C. sinensis worms. The functional characterization of CsGTP4 involved injecting its cRNA into Xenopus laevis oocytes and analyzing the deoxy-D-glucose uptake levels. The results demonstrated that deoxy-D-glucose uptake depended on the deoxy-D-glucose incubation and CsGTP4 expression time, but not sodium-dependent. The concentration-dependent uptake followed the Michaelis-Menten equation, with a Km value of 2.7 mM and a Vmax value of 476 pmol/oocyte/h based on the Lineweaver-Burk analysis. No uptake of radiolabeled α-ketoglutarate, p-aminohippurate, taurocholate, arginine, or carnitine was observed. The uptake of deoxy-D-glucose by CsGTP4 was significantly inhibited by unlabeled glucose and galactose in a concentration-dependent manner. It was significantly inhibited under strongly acidic and basic conditions. These insights into the glucose uptake kinetics and pH dependency of CsGTP4 provide a deeper understanding of nutrient acquisition in trematodes. This study contributes to the development of novel antiparasitic agents, addressing a considerable socioeconomic challenge in affected regions.

This study aimed to elucidate the clinical characteristics of patients diagnosed with toxoplasmosis in Korea. We collected and analyzed the specific research data of 5,917 patients from the Health Insurance Review and Assessment (HIRA; 2007-2020) and 533 electronic medical records (EMRs; 2003-2021) of Korean patients. The HIRA data showed that toxoplasmosis is an endemic disease that occurs constantly in Korea, with a large proportion of patients complaining of ocular symptoms. Of the 533 patients for whom EMR data were available, 54.6% were diagnosed with toxoplasmosis; ocular toxoplasmosis (35.7%), congenital toxoplasmosis (4.7%), cerebral toxoplasmosis (4.1%), pulmonary toxoplasmosis (0.4%), and toxoplasma hepatitis (0.6%), in order of frequency. In ocular cases, 54.4% of the patients had diverse ocular pathologies. Toxoplasmosis in Korea is characterized by a high frequency of ocular symptoms, most patients are adults, and 51.8% of patients with seropositivity were positive for IgG, suggesting prior infection. This study highlights that patients with ocular symptoms are included in the major diagnosis group for acquired toxoplasmosis in Korea.

This study surveyed the current status of intestinal parasite infections in Korean dog fecal samples. A total of 367 fecal samples were collected from the northern (Seoul and Gyeonggi-do), central (Chungcheong-do), and southern (Gyeongsang-do) regions and analyzed using the saturated sodium nitrate flotation technique and the nucleotide sequences of 18S rRNA. Six species of intestinal parasites were detected using the flotation technique. Among them, helminth eggs detected included Toxocara canis (6.0%), Toxascaris leonina (1.1%), Trichuris vulpis (6.8%), Ancylostoma caninum (2.7%), and Spirometra sp. (1.1%). Additionally, Cystoisospora sp. (7.6%) oocysts were also detected. The prevalence of intestinal parasite infections was higher in shelter dogs than in pet dogs. Molecular genetic assays revealed the gdh and 18S rRNA genes of Giardia duodenalis (type D) in 4.9% of fecal samples. To the best of our knowledge, 18S rRNA genes of Cryptosporidium canis were identified in 1.9% of fecal samples for the first time in Korea. These findings provide an overview of the current status of intestinal parasite infections in fecal samples of dogs from Korea and can be helpful in the surveillance of zoonotic parasite infections related to dogs.