Objective To investigate the effect of T cell immunoreceptor with Ig and ITIM domains (TIGIT) on the function of CD8⁺ T cells in the lungs of Plasmodium infected mice. Methods The lungs of the mice infected with Plasmodium yoelii were isolated, weighed and photographed after 12 days' infection. After dissolution, lung lymphocytes were isolated, counted and stained, and then the contents of CD8⁺ and TIGIT⁺CD8⁺ T cells were detected by flow cytometry. The expressions of L selectin (CD62L), CD69, programmed death 1 (PD-1), CD25, and C-X3-C motif chemokine receptor 1 (CX3CR1) on TIGIT⁺CD8⁺ T cells were detected by flow cytometry. After stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin, the ability of TIGIT⁺CD8⁺T cells to secrete interferon γ(IFN-γ), interleukin 21 (IL-21), IL-4, IL-17, and IL-10 was detected. Results The body mass of mice with Plasmodium infection was reduced. The lungs became darker, and the ratio of the lung mass to body mass was significantly increased. Compared with the normal mice, the percentages and absolute quantity of CD8⁺ and TIGIT⁺CD8⁺ T cells in the lungs of the infected mice were significantly increased. The percentage of TIGIT⁺CD8⁺ T cells expressing CD62L in the infected group was significantly lower, while the percentage of the CD69, PD-1, and CX3CR1 cells were significantly higher than that of TIGIT⁺CD8⁺ T cells from the normal mice. The percentages of TIGIT⁺CD8⁺ T cells secreting IL-21, IL-4, IL-17 and IL-10 cells in the infected group were significantly lower. Conclusion The lung lesions from mice with Plasmodium infection are obvious, the numbers of TIGIT⁺CD8⁺ T cells increase, and these cells express a variety of activation-related molecules, but the ability to secrete cytokines is reduced.
Animals ; Mice ; CD8-Positive T-Lymphocytes ; Cytokines/metabolism* ; Interferon-gamma/metabolism* ; Interleukin-10/metabolism* ; Interleukin-17/metabolism* ; Interleukin-4/metabolism* ; Lung/metabolism* ; Malaria/metabolism* ; Plasmodium yoelii/metabolism* ; Programmed Cell Death 1 Receptor/metabolism*

OBJECTIVE: To analyze the quality of blood smear examinations for malaria parasites in Chenzhou City, so as to provide insights into sustainable consolidation of malaria elimination achievements. METHODS: All positive blood smears from fever patients were irregularly sampled from each county (district) of Chenzhou City from 2018 to 2022 and reexamined, and no less than 3% negative blood smears were reexamined. The preparation, dyeing, cleanliness and microscopic examination results of blood smear were reexamined, and the quality of blood smear reexaminations was assessed using a descriptive statistical method. RESULTS: A total of 13 625 fever patients received blood smear examinations for malaria parasites in Chenzhou City from 2018 to 2022, of which 21 were positive and 13 604 were negative; 687 blood samples were reviewed, and the percentage of negative blood smear reexaminations was 4.90% (666/13 604), with a 63.51% rate of qualified negative blood smears preparation, a 67.87% rate of qualified dyeing and a 76.13% rate of qualified cleanliness, and no missing diagnosis found. There were 21 positive blood smears reexamined, and the proportions of qualified blood smears preparation, dyeing and cleanliness were all 85.71%, with 2 smears mistaking Plasmodium species (9.52%). The percentage of qualified negative blood smears preparation was 51.41% in 2022, which reduced by 31.61% in relative to that (75.17%) in 2019 (χ² = 9.033, P < 0.05), and the percentage of qualified negative blood smears dyeing was 60.19% in 2022, which reduced by 28.82% in relative to that (84.56%) in 2019 (χ² = 19.498, P < 0.05), while the percentage of qualified negative blood smears cleanliness was 62.96% in 2022, which reduced by 28.93% in relative to that (88.59%) in 2019 (χ² = 23.826, P < 0.001). In addition, there were no significant differences in the proportion of qualified negative blood smears preparation (χ² = 0.260, P > 0.05) or dyeing (χ² = 1.094, P > 0.05) among the three years, while a significant difference was detected in the percentage of qualified negative blood smears cleanliness (χ² = 12.175, P < 0.05). CONCLUSIONS No missing diagnosis was seen in blood smear examinations for malaria parasites among fever patients in Chenzhou City after malaria elimination; however, there were reductions in proportions of qualified blood smears preparation, dyeing and cleanliness. Quality control of blood smear examinations is recommended to be reinforced in key regions of Chenzhou City.
Animals ; Humans ; Parasites ; Malaria/prevention & control* ; Plasmodium ; Fever ; Microscopy

The dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes of Plasmodium vivax, as antifolate resistance-associated genes were used for drug resistance surveillance. A total of 375 P. vivax isolates collected from different geographical locations in China in 2009-2019 were used to sequence Pvdhfr and Pvdhps. The majority of the isolates harbored a mutant type allele for Pvdhfr (94.5%) and Pvdhps (68.2%). The most predominant point mutations were S117T/N (77.7%) in Pvdhfr and A383G (66.8%) in Pvdhps. Amino acid changes were identified at nine residues in Pvdhfr. A quadruple-mutant haplotype at 57, 58, 61, and 117 was the most frequent (57.4%) among 16 distinct Pvdhfr haplotypes. Mutations in Pvdhps were detected at six codons, and the double-mutant A383G/A553G was the most prevalent (39.3%). Pvdhfr exhibited a higher mutation prevalence and greater diversity than Pvdhps in China. Most isolates from Yunnan carried multiple mutant haplotypes, while the majority of samples from temperate regions and Hainan Island harbored the wild type or single mutant type. This study indicated that the antifolate resistance levels of P. vivax parasites were different across China and molecular markers could be used to rapidly monitor drug resistance. Results provided evidence for updating national drug policy and treatment guidelines.
Antimalarials/pharmacology* ; China/epidemiology* ; Drug Combinations ; Drug Resistance/genetics* ; Folic Acid Antagonists/pharmacology* ; Humans ; Mutation ; Plasmodium vivax/genetics* ; Prevalence

Arthropod-borne diseases, such as malaria and dengue fever, have frequently beset five countries(Cambodia, Vietnam, Laos, Myanmar, and Thailand) in the tropical rainy Lancang-Mekong region, which pose a huge threat to social production and daily life. As a resort to such diseases, chemical drugs risk the resistance in plasmodium, non-availability for dengue virus, and pollution to the environment. Traditional medicinal plants have the multi-component, multi-target, and multi-pathway characteristics, which are of great potential in drug development. Exploring potential medicinals for arthropod-borne diseases from traditional medicinal plants has become a hot spot. This study summarized the epidemiological background of arthropod-borne diseases in the Lancang-Mekong region and screened effective herbs from the 350 medicinal plants recorded in CHINA-ASEAN Traditional Medicine. Based on CNKI, VIP, and PubMed, the plants for malaria and dengue fever and those for killing and repelling mosquitoes were respectively sorted out. Their pharmacological effects and mechanisms were reviewed and the material basis was analyzed. The result is expected to serve as a reference for efficient utilization of medicinal resources, development of effective and safe drugs for malaria and dengue fever, and the further cooperation between China and the other five countries in the Lancang-Mekong region.
Animals ; Culicidae ; Malaria ; Plants, Medicinal ; Plasmodium ; Thailand

We aimed to assess the risks of
China ; Cryptosporidiosis/microbiology* ; Cryptosporidium/isolation & purification* ; Giardia/isolation & purification* ; Giardiasis/microbiology* ; Humans ; Risk Assessment ; Water Microbiology ; Water Supply/statistics & numerical data*

Pathogens like bacteria and protozoa, which affect human and animal health worldwide, can be transmitted by vectors like ticks. To investigate the epidemiology and genetic diversity of bacteria and protozoans carried by ticks in Chengmai county of Hainan province, China, 285 adult hard ticks belonging to two species [
Anaplasmataceae/isolation & purification* ; Animals ; Chaperonin 60/genetics* ; China ; Citrate (si)-Synthase/genetics* ; Coccidia/isolation & purification* ; Coxiellaceae/isolation & purification* ; Insect Vectors/microbiology* ; Islands ; Ixodidae/microbiology* ; Phylogeny ; Piroplasmia/isolation & purification* ; RNA, Ribosomal, 16S/genetics* ; RNA, Ribosomal, 18S/genetics*

As a unicellular organism, Plasmodium displays a panoply of lipid metabolism pathways that are seldom found together in a unicellular organism. These pathways mostly involve the Plasmodium-encoded enzymatic machinery and meet the requirements of membrane synthesis during the rapid cell growth and division throughout the life cycle. Different lipids have varied synthesis and meta-bolism pathways. For example, the major phospholipids are synthesized via CDP-diacylglycerol-dependent pathway in prokaryotes and de novo pathway in eukaryotes, and fatty acids are synthesized mainly via type Ⅱ fatty acid synthesis pathway. The available studies have demonstrated the impacts of artemisinin and its derivatives, the front-line compounds against malaria, on the lipid metabolism of Plasmodium. Therefore, this article reviewed the known lipid metabolism pathways and the effects of artemisinin and its derivatives on these pathways, aiming to deepen the understanding of lipid synthesis and metabolism in Plasmodium and provide a theoretical basis for the research on the mechanisms and drug resistance of artemisinin and other anti-malarial drugs.
Antimalarials/pharmacology* ; Artemisinins/therapeutic use* ; Humans ; Lipid Metabolism ; Malaria/drug therapy* ; Plasmodium

Plasmodium culture in vitro is often used as an antimalarial drug evaluation model, but the lifecycle of P. falciparum culture in vitro tends to be disordered, which affects the research and evaluation of antimalarial drug mechanism in vitro. By combining magnetic bead separation method with sorbitol synchronization method, a synchronization method was constructed to quickly acquire different lifecycles of P. falciparum and obtain large amounts of parasite with a narrow synchronization window in a short period. Furthermore, the dihydroartemisinin(DHA) was used to treat the early trophozoite phase of P. falciparum 3 D7 for 4 h. Then mRNA was extracted and RNA-seq was conducted to analyze the differential expression of mRNA after drug treatment and obtain the differential gene expression profile. Differential expression of up-regulated genes and down-regulated genes was analyzed according to the screening criteria of |log_2FC|>1 and P<0.05. There, 262 genes were up-regulated and 77 genes were down-regulated. GO functional enrichment analysis of all the differentially expressed genes showed that the enrichment items mainly included cell membrane components, transporter activity, serine/threonine kinase activity, Maurer's clefts(MCs), rhoptry, antigen variation and immune evasion. The enrichment of KEGG pathway included malaria, fatty acid metabolism and peroxisome. Protein-protein interaction(PPI) analysis showed that the down-regulated genes in the modules with high degree of association included rhoptry, myosin complex, transporter and other genes related to the important life activities of malaria invasion and immune escape; the up-regulated genes were mainly related to various toxic exportins of malaria, such as PfSBP1 of MCs. qRT-PCR was used to verify the expression level of some genes, and most of the results were the same as the sequencing results. SBP1 was significantly up-regulated, while some antigenic protein expression levels were down-regulated. Above all, key molecules of DHA therapy were mainly involved in the parasites' rhoptry, transporter, antigenic variation, plasmodium exportin. These results offer us many hints to guide the further studies on mechanism of artemisinin and provide a new way for development of new antimalarial drugs.
Animals ; Antimalarials ; Artemisinins ; Erythrocytes ; Plasmodium falciparum ; Transcriptome

Simian malaria is a zoonotic disease caused by Plasmodium knowlesi infection. The common natural reservoir of the parasite is the macaque monkey and the vector is the Anopheles mosquito. Human cases of P. knowlesi infection has been reported in all South East Asian countries in the last decade, and it is currently the most common type of malaria seen in Malaysia and Brunei. Between 2007–2017, 73 cases of P. knowlesi infection were notified and confirmed to the Ministry of Health in Brunei. Of these, 15 cases (21%) were documented as work-related, and 28 other cases (38%) were classified as probably related to work (due to incomplete history). The occupations of those with probable and confirmed work related infections were border patrol officers, Armed Forces and security personnel, Department of Forestry officers, boatmen and researchers. The remaining cases classified as most likely not related to work were possibly acquired via peri-domestic transmission. The risk of this zoonotic infection extends to tourists and overseas visitors who have to travel to the jungle in the course of their work. It can be minimised with the recommended use of prophylaxis for those going on duty into the jungles, application of mosquito/insect repellants, and use of repellant impregnated uniforms and bed nets in jungle camp sites.
Anopheles ; Arm ; Asian Continental Ancestry Group ; Brunei ; Culicidae ; Forestry ; Haplorhini ; Humans ; Macaca ; Malaria ; Malaysia ; Occupations ; Parasites ; Plasmodium knowlesi ; Plasmodium ; Zoonoses

Cryptosporidium is a common intestinal protozoan that can lead to diarrhea in humans and dogs. The predominant species of infection are C. hominis and C. parvum in humans, and C. canis in dogs. However, C. canis can infect immunocompromised humans. Considering the close contact with humans, dogs have the potential to be reservoirs for human cryptosporidiosis. Breeding kennels are the major supply source of puppies for pet shops. The present study is to determine the molecular prevalence and characteristics of Cryptosporidium spp. found in breeding kennel dogs. A total of 314 fecal samples were collected from young and adult dogs kept in 5 breeding kennels. A polymerase chain reaction targeting the small subunit rRNA gene was employed for the detection of Cryptosporidium spp. To determine the species, the DNA sequences were compared to GenBank data. Overall, 21.0% of the fecal samples were positive for Cryptosporidium spp. infection. Cryptosporidium spp. was detected in all 5 facilities. A sequencing analysis demonstrated that all isolates shared 99–100% similarity with C. canis. The results suggest that Cryptosporidium spp. infection is present at a high-level in breeding kennel dogs. However, because dominant species in this survey was C. canis, the importance of breeding kennel dogs as reservoirs for Cryptosporidium spp. transmission to humans is likely to be low in Japan.
Adult ; Animals ; Base Sequence ; Breeding ; Cryptosporidiosis ; Cryptosporidium ; Databases, Nucleic Acid ; Diarrhea ; Dogs ; Genes, rRNA ; Humans ; Japan ; Polymerase Chain Reaction ; Prevalence