Detection of Parasites in the Field: The Ever-Innovating CRISPR/Cas12a

The rapid and accurate identification of parasites is crucial for prompt therapeutic intervention in parasitosis and effective epidemiological surveillance. For accurate and effective clinical diagnosis, it is imperative to develop a nucleic-acid-based diagnostic tool that combines the sensitivity and specificity of nucleic acid amplification tests (NAATs) with the speed, cost-effectiveness, and convenience of isothermal amplification methods. A new nucleic acid detection method, utilizing the clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) nuclease, holds promise in point-of-care testing (POCT). CRISPR/Cas12a is presently employed for the detection of Plasmodium falciparum, Toxoplasma gondii, Schistosoma haematobium, and other parasites in blood, urine, or feces. Compared to traditional assays, the CRISPR assay has demonstrated notable advantages, including comparable sensitivity and specificity, simple observation of reaction results, easy and stable transportation conditions, and low equipment dependence. However, a common issue arises as both amplification and cis-cleavage compete in one-pot assays, leading to an extended reaction time. The use of suboptimal crRNA, light-activated crRNA, and spatial separation can potentially weaken or entirely eliminate the competition between amplification and cis-cleavage. This could lead to enhanced sensitivity and reduced reaction times in one-pot assays. Nevertheless, higher costs and complex pre-test genome extraction have hindered the popularization of CRISPR/Cas12a in POCT.

Characterization of the complete mitochondrial genome and phylogenetic analyses of Haemaphysalis tibetensis Hoogstraal, 1965 (Acari: Ixodidae)

Ticks are specialized ectoparasites that feed on blood, causing physical harm to the host and facilitating pathogen transmission. The genus Haemaphysalis contains vectors for numerous infectious agents. These agents cause various diseases in humans and animals. Mitochondrial genome sequences serve as reliable molecular markers, forming a crucial basis for evolutionary analyses, studying species origins, and exploring molecular phylogeny. We extracted mitochondrial genome from the enriched mitochondria of Haemaphysalis tibetensis and obtained a 14,714-bp sequence. The mitochondrial genome consists of 13 protein-coding genes (PCGs), two ribosomal RNA, 22 transfer RNAs (tRNAs), and two control regions. The nucleotide composition of H. tibetensis mitochondrial genome was 38.38 % for A, 9.61 % for G, 39.32 % for T, and 12.69 % for C. The A + T content of H. tibetensis mitochondrial genome was 77.7 %, significantly higher than the G + C content. The repeat units of H. tibetensis exhibited two identical repeat units of 33 bp in length, positioned downstream of nad1 and rrnL genes. Furthermore, phylogenetic analyses based on the 13 PCGs indicated that Haemaphysalis tibetensis (subgenus Allophysalis) formed a monophyletic clade with Haemaphysalis nepalensis (subgenus Herpetobia) and Haemaphysalis danieli (subgenus Allophysalis). Although the species Haemaphysalis inermis, Haemaphysalis kitaokai, Haemaphysalis kolonini, and Haemaphysalis colasbelcouri belong to the subgenus Alloceraea, which were morphologically primitive hemaphysalines just like H. tibetensis, these four tick species cannot form a single clade with H. tibetensis. In this study, the whole mitochondrial genome sequence of H. tibetensis from Tibet was obtained, which enriched the mitochondrial genome data of ticks and provided genetic markers to study the population heredity and molecular evolution of the genus Haemaphysalis.

Characterization of the Complete Mitochondrial Genome and Phylogenetic Analyses of Eurytrema coelomaticum (Trematoda: Dicrocoeliidae)

Eurytrema coelomaticum, a pancreatic fluke, is recognized as a causative agent of substantial economic losses in ruminants. This infection, commonly referred to as eurytrematosis, is a significant concern due to its detrimental impact on livestock production. However, there is a paucity of knowledge regarding the mitochondrial genome of E. coelomaticum. In this study, we performed the initial sequencing of the complete mitochondrial genome of E. coelomaticum. Our findings unveiled that the mitochondrial genome of E. coelomaticum spans a length of 15,831 bp and consists of 12 protein-coding genes, 22 tRNA genes, two rRNA genes, and two noncoding regions. The A+T content constituted 62.49% of the genome. Moreover, all 12 protein-coding genes of E. coelomaticum exhibit the same arrangement as those of E. pancreaticum and other published species belonging to the family Dicrocoeliidae. The presence of a short string of additional amino acids (approximately 20~23 aa) at the N-terminal of the cox1 protein in both E. coelomaticum and E. pancreaticum mitochondrial genomes has contributed to the elongation of the cox1 gene in genus Eurytrema, surpassing that of all previously sequenced Dicrocoeliidae. The phylogenetic analysis displayed a close relationship between E. coelomaticum and E. pancreaticum, along with a genus-level association between Eurytrema and Lyperosomum. These findings underscore the importance of mitochondrial genomic data for comparative studies of Dicrocoeliidae and even Digenea, offering valuable DNA markers for future investigations in the systematic, epidemiological, and population genetic studies of this parasite and other digenean trematodes.

[Preliminary study on the expression of MIF in HCC tissues and its relationship with ERK1/2 signaling pathway]

Objective: To investigate the expression of Macrophage migration-inhibitory factors (MIF) in hepatocellular carcinoma (HCC) tissues and its interaction with ERK1/2 signaling pathway, so as to establish a theoretical basis for further studying the molecular mechanism of MIF promoting HCC. Methods: From February 2020 to August 2021, 52 cases of hepatocellular carcinoma (HCC) tissues based on hepatitis B cirrhosis (HBV-LC) and 52 cases of adjacent tissues in Tianjin Medical University Cancer Hospital and 940th Hospital of Joint Logistic Support Force of PLA were collected as the experimental group, including 39 males and 13 females, aged 35-65 years. And 20 cases of normal liver tissue were selected as the control group. Immunohistochemistry was used to detect the expression of MIF, ERK1/2 and p-ERK1/2 proteins in liver tissues of the two groups, and in situ hybridization was used to detect the expression of ERK1/2 nucleic acid in liver tissues of the two groups.HepG2 HCC cells and L-02 normal hepatocytes were co-cultured with different concentrations of rMIF, the expression and phosphorylation levels of ERK1/2 and JNK1 proteins in the two kinds of liver cells were detected by Western-blot, and the expression levels of ERK1/2 nucleic acids in the two kinds of liver cells were detected by RT-PCR. One-way ANOVA was used for measurement data and χ² test was used for counting data. Results: The expressions of MIF, ERK1/2, p-ERK1/2 and ERK1/2 mRNA were significantly increased in HCC and para-cancer tissues (the expression of MIF in HCC group was 78.8%, and that in adjacent group was 75.0%; ERK1/2 80.8% in HCC group and ERK1/2 71.8% in paracancerous group. The expression of p-ERK1/2 75.0 % in HCC group and 46.2% in paracancerous group were respectively detected. ERK1/2 mRNA was expressed in HCC group 76.9%, ERK1/2 mRNA expression in paracancerous group 78.8%), and the differences were statistically significant compared with normal liver tissues (P<0.05), but there was no significant difference between HCC and para-cancer tissues (P>0.05). The expressions of ERK1/2, p-ERK1/2 and ERK1/2 mRNA in HepG2 HCC cells were significantly increased with the increase of rMIF concentration, and the increase was most obvious when rMIF concentration was 200 ng/ml, and the difference was statistically significant compared with L-02 normal hepatocytes (P<0.05). Conclusion: MIF, ERK1/2 and p-ERK1/2 are highly expressed in HCC tissues and HepG2 HCC cells, suggesting that MIF promotes the occurrence and development of hepatocellular carcinoma through ERK1/2 signaling pathway.

Echinococcus multilocularis drives the polarization of macrophages by regulating the RhoA-MAPK signaling pathway and thus affects liver fibrosis

Echinococcus multilocularis is a small parasite that causes alveolar echinococcosis. It primarily induces liver disorder, such as liver fibrosis and even liver cancer, which severely endangers human lives. This study aims to explore the efficacy of Echinococcus multilocularis soluble antigen in preventing and alleviating alveolar echinococcosis-induced liver fibrosis and determine the underlying mechanism. We first identified the optimal dose and time of Echinococcus multilocularis soluble antigen. The protein levels of key genes in the RhoA-MAPK signaling pathway were remarkably upregulated in RAW264.7 and Ana-1 cells induced with 80 μg/mL Echinococcus multilocularis soluble antigen for 8 h. Interestingly, the upregulated expression levels were remarkably reversed by the RhoA, JNK, ERK, or p38 inhibitor, confirming the significance of the RhoA-MAPK signaling pathway. In addition, the relative contents of M2 polarization markers IL-10 and Arg-1 in macrophages induced with 80 μg/mL Echinococcus multilocularis soluble antigen for 8 h increased, whereas those of M1 polarization markers IL-12 and NOS-2 decreased. Mouse hepatic stellate cells were the key components of the hepatocellular carcinoma tumor microenvironment. Hepatic stellate cells were activated by Echinococcus multilocularis soluble antigen and transformed into the morphology of myofibroblasts in response to liver disorders. By detecting the marker of myofibroblast formation, RhoA inhibitor remarkably reduced the positive expression of α-SMA in mouse hepatic stellate cells induced with Echinococcus multilocularis soluble antigen. Therefore, Echinococcus multilocularis soluble antigen remarkably activated the RhoA-MAPK pathways in macrophages, further inducing the polarization of macrophages and ultimately causing liver fibrosis. Hypothesis: We hypothesize that infection with Echinococcus multilocularis activates the RhoA-MAPK signaling pathway and subsequently induces macrophage polarization to promote hepatic stellate cells activation leading to liver fibrosis. Aims: To investigate the mechanism by which soluble antigen of Echinococcus multilocularis affects liver fibrosis through the RhoA-MAPK pathway driving polarization of macrophages. Goals: To identify new pathways of intervention and drug targets for the regulation of macrophage polarity phenotype switching and the attenuation or inhibition of the development and treatment of liver fibrosis caused by Echinococcus multilocularis infection.

A 2-year locomotive exploration and scientific investigation of the lunar farside by the Yutu-2 rover

The lunar nearside has been investigated by many uncrewed and crewed missions, but the farside of the Moon remains poorly known. Lunar farside exploration is challenging because maneuvering rovers with efficient locomotion in harsh extraterrestrial environment is necessary to explore geological characteristics of scientific interest. Chang'E-4 mission successfully targeted the Moon's farside and deployed a teleoperated rover (Yutu-2) to explore inside the Von Kármán crater, conveying rich information regarding regolith, craters, and rocks. Here, we report mobile exploration on the lunar farside with Yutu-2 over the initial 2 years. During its journey, Yutu-2 has experienced varying degrees of mild slip and skid, indicating that the terrain is relatively flat at large scales but scattered with local gentle slopes. Cloddy soil sticking on its wheels implies a greater cohesion of the lunar soil than encountered at other lunar landing sites. Further identification results indicate that the regolith resembles dry sand and sandy loam on Earth in bearing properties, demonstrating greater bearing strength than that identified during the Apollo missions. In sharp contrast to the sparsity of rocks along the traverse route, small fresh craters with unilateral moldable ejecta are abundant, and some of them contain high-reflectance materials at the bottom, suggestive of secondary impact events. These findings hint at notable differences in the surface geology between the lunar farside and nearside. Experience gained with Yutu-2 improves the understanding of the farside of the Moon, which, in return, may lead to locomotion with improved efficiency and larger range.

Rescue of cardiac function in obese type-2 diabetic mice by transfer of a human longevity gene

Background

Healthy longevity is the result of the interaction between favourable environment and unique genetic makeup. We showed that horizontal transfer of a longevity-associated gene variant (LAV-BPIFB4) improves endothelial function and accelerates the recovery from ischemia.

Purpose

To determine if the benefit of LAV-BPIFB4 gene therapy can be extended to diabetic cardiomyopathy.

Methods and results

We confirmed that human diabetic patients with heart failure (n=13) show a decreased cardiac expression of BPIFB4 compared with healthy subjects (n=10). Obese db/db mice received a systemic injection of adeno-associated viral vector (AAV9)-LAV-BPIFB4, AAV9-wild type (WT)-BPIFB4 (both 100 μL at 1×1012 GC/mL) or vehicle before the onset of cardiomyopathy, and were euthanised four weeks later for histological, metabolic and transcriptional analyses. Echocardiographic evaluation (n=8/group), performed at baseline and after gene therapy, showed that LAV-BPIFB4 treatment, despite not resolving hyperglycaemia, improved left ventricular function compared with the other groups. Histological analyses of the hearts (n=5 to 10/group) revealed that LAV-BPIFB4 reduced myocardial fibrosis and increased angiogenesis compared with vehicle and WT-hearts; moreover, LAV increased the expression of the alpha-isoform of the cardiac myosin heavy chain, which is associated with a superior cardiomyocyte contractility. Interestingly, LAV-BPIFB4 treatment induced an increase in cardiac SDF1 expression compared with WT and vehicle, despite the mechanism linking the two events is still unknown. The oral administration of the CXCR4 antagonist AMD-070, given at 2 mg/kg/day for four weeks, abolished several of the beneficial effects exerted by the LAV-BPIFB4 therapy in the obese diabetic mice, as assessed by echocardiography and histology (n=7/group).

At the molecular level, next-generation RNA sequencing (n=3 to 4 /group) showed 8 genes were differentially expressed by LAV-BPIFB4-hearts compared with vehicle-hearts. These genes are associated with mitochondrial and metabolic functions. Among them, changes in the UCP3, HMGCS2, CS, ATPB and TOMM20 expression were also validated at the protein level by western blotting. Lipidomics using ultrahigh-performance liquid chromatography-mass spectrometry (n=6 or 7/group) showed 63 metabolites differentially expressed by LAV-BPIFB4- compared with vehicle-hearts, with only 3 (two cardiolipins and one glycerophospholipid) returning close to the non-diabetic phenotype following LAV-BPIFB4 treatment.

Conclusions

This study newly shows the possibility of transferring the benefit of salutary polymorphic gene variants to protect the cardiovascular system from metabolic pressure. Rather than combating pathogenic mechanisms, the strategy activates alternative pathways overriding disease risk factors.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation project grant “Longevity-associated BPIFB4 gene therapy for treatment of ischemic disease”

Contribution to the echinococcosis control programme in China by NIPD-CTDR

As a zoonotic parasitosis caused by the parasitism of Echinococcus larvae, echinococcosis imposes serious disease and economic burdens on human beings and society, and is thus a global public health issue. Its complex life history, wide distribution, the combined influence of various epidemic factors, coupled with the unique natural environment, customs, and religious beliefs in endemic areas, pose a huge challenge to the national echinococcosis control programme in China. Accurate early detection and confirmation of diagnosis of echinococcosis, the use of effective drugs, real-time surveillance of the infection status of populations and various hosts, controlling the source of infection, and blocking the route of transmission are of enormous significance for control. In this paper, the work by NIPD-CTDR on the prevention and control of echinococcosis in China is reviewed, with a view to providing reference for the further promotion of the national echinococcosis control programme.

Old drug repurposing for neglected disease: Pyronaridine as a promising candidate for the treatment of Echinococcus granulosus infections

Background

Cystic echinococcosis (CE), a condition caused by the larval stage of the dog tapeworm Echinococcus granulosus sensu stricto, is a globally distributed zoonotic disease. Current treatment options for CE are limited, and an effective and safe anti-echinococcal drug is urgently required.

Methods

Drug repurposing strategy was employed to identify new therapeutic agents against echinococcal cysts. An in vitro protoscolicidal assay along with in vivo murine models was applied in the drug screening. A microinjection procedure was employed to mimic the clinical PAIR (puncture, aspiration, injection and reaspiration) technique to evaluate the potential application of the candidate drug in clinical practice.

Findings

We repurposed pyronaridine, an approved antimalarial drug, for the treatment of CE. Following a three-dose intraperitoneal regimen (57 mg/kg, q.d. for 3 days), pyronaridine caused 100% cyst mortality. Oral administration of pyronaridine at 57 mg/kg, q.d. for 30 days significantly reduced the parasitic burden in the pre-infected mice compared with albendazole group (p < 0.001). Using a microinjection of drug into cysts, pyronaridine (200 μM) showed highly effective in term of inhibition of cyst growth (p < 0.05, compared with saline group). Pharmacokinetic analysis revealed that pyronaridine was highly distributed in the liver and lungs, the most affected organs of CE. Function analysis showed that pyronaridine inhibited the activity of topoisomerase I (IC₅₀ = 209.7 ± 1.1 μM). In addition, classical apoptotic hallmarks, including DNA fragmentation and caspase activation, were triggered.

Interpretation

Given its approved clinical safety, the repurposing of pyronaridine offers a rapidly translational option for treating CE including PAIR.

Fund

National Natural Science Foundation of China and International Cooperation Project of the Qinghai Science and Technology Department.

The effects of CCR7 and related signaling pathways on Leishmania major -infected human dendritic cells

OBJECTIVES

In our research, we aimed to investigate the roles of CC-chemokine receptor 7 (CCR7) and relevant signaling pathways in Leishmania major-infected human dendritic cells (DCs).

METHODS

Differentially expressed genes (DEGs) in L. major-infected human DCs were selected out and visualized using R program. Kyoto Encyclopedia of Genes and Genomes pathway analysis was conducted for investigation of significantly enriched signaling pathways and Gene Ontology enrichment analysis was carried out for the unveiling of enriched Molecular Functions and Biological Processes in L. major-infected human DCs. Besides, Hub gene was screened out using weighted gene coexpression network analysis and Cytoscape. In addition, enzyme-linked immunosorbent assay and real-time quantitative polymerase chain reaction were used for detection of relative expression of CCR7, interleukin-12 (IL-12), and interferon-γ (IFN-γ) in L. major-infected human DCs and western blot analysis was used for detection of relative expression of CCR7 and other proteins in JAK-STAT signaling pathway in L. major-infected human DCs.

RESULTS

CCR7 was upregulated and both chemokine and JAK-STAT signaling pathway were activated in L. major-infected human DCs. During the L. major infection, total number of L. major-infected human DCs were increased, as well as the relative expression levels of CCR7, IL-12, and IFN-γ and proteins in the JAK-STAT signaling pathway. Overexpression of CCR7 not only increased expression levels of IL-12 and IFN-γ but also activated the JAK-STAT signaling pathway to affect the leishmaniasis progression.

CONCLUSION

L. major infection-induced activation of CCR7, as well as JAK2 and STAT1, might well upregulate the expression of BAX yet suppress the expression of both Bcl2 and c-Jun to affect leishmaniasis progression.

In vitro and in vivo efficacies of carbazole aminoalcohols in the treatment of alveolar echinococcosis

Benzimidazoles, including albendazole and mebendazole, are the major drugs for clinical chemotherapy of echinococcosis. They mainly exert parasitostatic effects depending on high dosages for long-term. Previous studies have identified carbazole aminoalcohols as novel anti-CE (cystic echinococcosis) agents. However, it is still to be confirmed whether it is effective on alveolar echinococcosis (AE) or not. In the present study, efficacies of novel carbazole aminoalcohols, propylamine, R-propylamine and S-propylamine were evaluated under in vitro and in vivo conditions. Carbazole aminoalcohols were tested against Echinococcus multilocularis (E. multilocularis) protoscoleces (PSC) in vitro. The effects of propylamine and R-propylamine exhibited a time-dependent manner at different concentrations, while the effect of S-propylamine was very poor. At a concentration of 20 μM, the mortality of PSC achieved to 100% on the 11th day after exposure to R-propylamine. The treatment of carbazole aminoalcohols to infected mice resulted in statistically significant reductions in the cyst weights compared with those obtained from negative control mice (p < 0.05), and no significant differences were found between albendazole and carbazole aminoalcohols (p > 0.05). The cytotoxicity examination in rat hepatoma (RH) cells indicated that propylamine and R/S-propylamine were lower that of albendazole at a low concentration (5 μM). In addition, histopathological observation of organs (liver, spleen and kidney) for experimental mice showed mild inflammatory changes in the liver and spleen. This study reveals the potential of carbazole aminoalcohols as a class of novel anti-AE agents.

Heat shock protein 47 effects on hepatic stellate cell-associated receptors in hepatic fibrosis of Schistosoma japonicum-infected mice

The study aimed to explore the regulation of heat shock protein 47 (HSP47) on expressions of receptors associated with hepatic stellate cell (HSC) in liver fibrosis mouse models induced bySchistosoma japonicum(S. japonicum). Mouse fibroblasts (NIH/3T3) were transfected with HSP47 shRNA plasmid by lipofectamine transfection, and experimental fibrosis in HSCs was studied inS. japonicummouse models treated with HSP47 shRNAin vivo. HSP47 expression was assessed using Western blot and real-time PCR. Flow cytometry was adopted to determine the expression of cell membrane receptors. HSP47-shRNA could markedly down-regulate the expression of collagen (Col1a1 and Col3a1). The expressions of HSP47, endothelin receptor A (ETAR) and endothelin receptor B (ETBR) significantly increased in the liver tissue of infected mice. However, the expressions of ETAR and HSP47 and ETBR remarkably decreased after the administration of HSP47 shRNAin vitroandin vivo. ETAR and ETBR levels were found to be positively correlated with HSP47 expression. HSP47 might exert influence on liver fibrosis via the regulation of ETAR and ETBR.

Limited fertility of the subcutaneous cysts of Echinococcus multilocularis

Echinococcus multilocularis is a tiny devastating worm that causes alveolar echinococcosis in humans. This disease mainly occurs in the liver but rarely in other organs. We report the subcutaneous encystment of E. multilocularis metacestodes in experimentally infected mice. Subcutaneous cysts had remarkably fewer protoscoleces (2.05 ± 1.47, n = 20) and small irregular-shape vesicles (ISVs) in the lumen as compared to liver cysts (69.6 ± 55.65, n = 10). Moreover, abnormal development of a protoscolex was also observed in a subcutaneous cyst. The results suggest that subcutaneous encystment may have potential adverse effects on the reproductivity and development of protoscoleces, providing potential explanations for high tissue preference of metacestode encystment.

An epidemiological survey of echinococcosis in intermediate and definitive hosts in Qinghai Province, China

In order to understand the epidemiological status of alveolar and cystic echinococcosis in intermediate and definitive hosts in Qinghai Province, China, during the period 2007-2011, we investigated the infection in humans and animals, including yaks, Tibetan sheep, Tibetan dogs, and wild foxes distributed in different counties around the province. Sera from local residents were examined using a rapid serodiagnostic kit to detect specific antibodies against Echinococcus. Seropositive samples were confirmed with B-scan ultrasonography and X-ray examinations. Yaks and Tibetan sheep were checked at slaughterhouses, and cysts and suspicious lesions were collected for analysis. A rapid diagnostic strip was used to detect Echinococcus adults in Tibetan dogs. Positive dogs were dewormed and the parasites collected. Wild foxes were trapped and necropsies performed with particular attention to the intestine. Forty-eight of 735 (6.4%) humans tested were positive and 475 of 854 (55.6%) Tibetan sheep and 85 of 352 (24.15%) yaks were infected with Echinococcus. Across different counties, 214 of 948 (22.57%) Tibetan dogs were positive, and five of 36 (13.9%) wild foxes were infected with Echinococcus. Molecular studies showed that all the infections detected in humans, domestic yaks, and Tibetan sheep were the G1 genotype (E. granulosus), whereas the parasites from Tibetan foxes and Tibetan dogs were E. shiquicus and E. multilocularis, respectively. In conclusion, Echinococcosis is hyperendemic in Qinghai Province in both its intermediate and definitive hosts and the G1 genotype of cystic Echinococcus is the dominant strain.

Analysis on Gene Expression Profile in Oncospheres and Early Stage Metacestodes from Echinococcus multilocularis

Alveolar echinococcosis is a worldwide zoonosis of great public health concern. Analysis of genome data for Echinococcus multilocularis has identified antigen families that can be used in diagnostic assays and vaccine development. However, little gene expression data is available for antigens of the egg and early larval stages. To address this information gap, we used a Next-Generation Sequencing approach to investigate three different stages (non-activated and activated oncospheres, and early stage metacestodes) of E. multilocularis (Nemuro strain). Transcriptome data analysis revealed that some diagnostic antigen gp50 isoforms and the antigen Eg95 family dominated in activated oncospheres, and the antigen B family dominated in early stage metacestodes. Furthermore, heat shock proteins and antigen II/3 are constantly expressed in the three stages. The expression pattern of various known antigens in E. multilocularis may give fundamental information for choosing candidate genes used in diagnosis and vaccine development.

An epidemiological study of Hypoderma infection and control using ivermectin in yaks in Qinghai Province, China

The prevalence of Hypoderma spp. in yaks grazed in the east of Qinghai province was investigated in 2008. In this area, the prevalence in young yaks (1- to 3-year-old) was very high at 82.2–98.7%, whilst in adult yaks (4-year-old and older), the prevalence was 42.4–50.6%. The seasonal development and migration pattern of Hypoderma larvae in yak bodies was found to be similar for different locations in this area. The numbers of first, second and third instar larvae detected in yak bodies peaked in October, December and March, respectively. Different doses of ivermectin (125 to 500 µg/kg body weight) almost completely dewormed the larvae from yaks, suggesting that using a quarter of the prescribed dose (500 µg/kg body weight) was effective. In October of each year between 2009 and 2012, ivermectin (125 µg/kg body weight) was administered to a total of 562,995 yaks grazed in four counties in Qinghai province, and the pevalence of Hypoderma larval infection in yaks was reduced to 0.5–1.0%.

Mucosal adjuvanticity of fibronectin-binding peptide (FBP) fused with Echinococcus multilocularis tetraspanin 3: systemic and local antibody responses

Background

Studies have shown that a bacterial fibronectin attachment protein (FAP) is able to stimulate strong systemic and mucosal antibody responses when it is used alone or co-administrated with other antigens (Ags). Thus, it has been suggested to be a promising adjuvant candidate for the development of efficient vaccines. However, the co-administered Ags and FAP were cloned, expressed and purified individually to date. In a recent study, we first evaluated the adjuvanticity of a fibronectin-binding peptide (FBP, 24 amino acids) of Mycobacterium avium FAP fused with Echinococcus multilocularis tetraspanin 3 (Em-TSP3) by detecting systemic and local antibody responses in intranasally (i.n.) immunized BALB/c mice.

Methodology/Principal Findings

Em-TSP3 and FBP fragments were linked with a GSGGSG linker and expressed as a single fusion protein (Em-TSP3-FBP) using the pBAD/Thio-TOPO expression vector. BALB/c mice were immunized i.n. with recombinant Em-TSP3-FBP (rEm-TSP3-FBP) and rEm-TSP3+CpG and the systemic and local antibody responses were detected by ELISA. The results showed that both rEm-TSP3-FBP and rEm-TSP3+CpG evoked strong serum IgG (p<0.001) and IgG1 responses (p<0.001), whereas only the latter induced a high level IgG2α production (p<0.001), compared to that of rEm-TSP3 alone without any adjuvant. There were no significant differences in IgG and IgG1 production between the groups. Low level of serum IgA and IgM were detected in both groups. The tendency of Th1 and Th2 cell immune responses were assessed via detecting the IgG1/IgG2α ratio after the second and third immunizations. The results indicated that i.n. immunization with rEm-TSP3-FBP resulted in an increased IgG1/IgG2α ratio (a Th2 tendency), while rEm-TSP3+CpG caused a rapid Th1 response that later shifted to a Th2 response. Immunization with rEm-TSP3-FBP provoked significantly stronger IgA antibody responses in intestine (p<0.05), lung (p<0.001) and spleen (p<0.001) compared to those by rEm-TSP3+CpG. Significantly high level IgA antibodies were detected in nasal cavity (p<0.05) and liver (p<0.05) samples from both groups when compared to rEm-TSP3 alone without any adjuvant, with no significant difference between them.

Conclusions

I.n. administration of rEm-TSP3-FBP can induce strong systemic and mucosal antibody responses in immunized BALB/c mice, suggesting that fusion of Em-TSP3 with FBP is a novel, prospective strategy for developing safe and efficient human mucosal vaccines against alveolar echinococcosis (AE).

Echinococcus metacestodes form a laminated layer and develop strategies to escape host immune responses once the infection established on the liver of intermediated host. One of the most important strategies is thought to be immunoregulation, where some molecules (e.g., antigen B) impair dendritic cell (DC) differentiation and polarize immature DC maturation towards a non-protective Th2 cell response. Therefore, it is more feasible to kill Echinococcus oncospheres in the early stage of infection in the intestine and blood. Systemic and local immune responses are believed to play a crucial role on oncosphere exclusion. Among antigen delivery systems, i.n. administration is the most efficient one, inducing both systemic and a full-range of mucosal immune responses. FAP is necessary to M. avium and S. pyogenes to efficiently attach and invade epithelial cells, and has been suggested as a potent vaccine adjuvant. Mucosal immune responses are induced after FAP binds to the fibronectin protein of host microfold (M) cells and DCs are activated. We developed a one-step delivery system where FAP and other Ags can be expressed, purified and immunized as one protein. The systemic and, in particular, the mucosal antibody responses induced by the fusion protein were detected to evaluate the adjuvanticity of FBP.

A pilot study on developing mucosal vaccine against alveolar echinococcosis (AE) using recombinant tetraspanin 3: Vaccine efficacy and immunology

Background

We have previously evaluated the vaccine efficacies of seven tetraspanins of Echinococcus multilocularis (Em-TSP1–7) against alveolar echinococcosis (AE) by subcutaneous (s.c.) administration with Freund's adjuvant. Over 85% of liver cyst lesion number reductions (CLNR) were achieved by recombinant Em-TSP1 (rEm-TSP1) and -TSP3 (rEm-TSP3). However, to develop an efficient and safe human vaccine, the efficacy of TSP mucosal vaccines must be thoroughly evaluated.

Methodology/Principal Findings

rEm-TSP1 and -TSP3 along with nontoxic CpG ODN (CpG oligodeoxynucleotides) adjuvant were intranasally (i.n.) immunized to BALB/c mice and their vaccine efficacies were evaluated by counting liver CLNR (experiment I). 37.1% (p<0.05) and 62.1% (p<0.001) of CLNR were achieved by these two proteins, respectively. To study the protection-associated immune responses induced by rEm-TSP3 via different immunization routes (i.n. administration with CpG or s.c. immunization with Freund's adjuvant), the systemic and mucosal antibody responses were detected by ELISA (experiment II). S.c. and i.n. administration of rEm-TSP3 achieved 81.9% (p<0.001) and 62.8% (p<0.01) CLNR in the liver, respectively. Both the immunization routes evoked strong serum IgG, IgG1 and IgG2α responses; i.n. immunization induced significantly higher IgA responses in nasal cavity and intestine compared with s.c. immunization (p<0.001). Both immunization routes induced extremely strong liver IgA antibody responses (p<0.001). The Th1 and Th2 cell responses were assessed by examining the IgG1/IgG2α ratio at two and three weeks post-immunization. S.c. immunization resulted in a reduction in the IgG1/IgG2α ratio (Th1 tendency), whereas i.n. immunization caused a shift from Th1 to Th2. Moreover, immunohistochemistry showed that Em-TSP1 and -TSP3 were extensively located on the surface of E. multilocularis cysts, protoscoleces and adult worms with additional expression of Em-TSP3 in the inner part of protoscoleces and oncospheres.

Conclusions

Our study indicated that i.n. administration of rEm-TSP3 with CpG is able to induce both systemic and local immune responses and thus provides significant protection against AE.

Humans and rodents become infected with E. multilocularis by oral ingesting of the eggs, which then develop into cysts in the liver and progress an endless proliferation. Untreated AE has a fatality rate of >90% in humans. Tetraspanins have been identified in Schistosoma and showed potential as the prospective vaccine candidates. In our recent study, we first identified seven tetraspanins in E. multilocularis and evaluated their protective efficacies as vaccines against AE when subcutaneously administered to BALB/c mice. Mucosal immunization of protective proteins is able to induce strong local and systemic immune responses, which might play a crucial role in protecting humans against E. multilocularis infection via the intestine, blood and liver. We focused on Em-TSP3, which achieved significant vaccine efficacy via both s.c. and i.n. routes. The adjuvanticity of nontoxic CpG OND as i.n. vaccine adjuvant was evaluated. The widespread expression of Em-TSP3 in all the developmental stages of E. multilocularis, and the strong local and systemic immune responses evoked by i.n. administration of rEm-TSP3 with CpG OND adjuvant suggest that this study might open the way for developing efficient, nontoxic human mucosal vaccines against AE.

Construction of an artificial microalgal-bacterial consortium that efficiently degrades crude oil

Four oil component-degrading bacteria and one oil-tolerant microalgae, Scenedesmus obliquus GH2, were used to construct an artificial microalgal-bacterial consortium for crude-oil degradation. The bacterial strains included Sphingomonas GY2B and Burkholderia cepacia GS3C, along with a mixed culture, named GP3, containing Pseudomonas GP3A and Pandoraea pnomenusa GP3B. GY2B could only degrade polycyclic aromatic hydrocarbons, GS3C was able to degrade aliphatic chain hydrocarbons, and GP3 could utilize both saturated and aromatic hydrocarbons. In combination with unialgal or axenic algae, the bacteria showed different effects on oil degradation. Unialgal GH2 was not suitable for the consortium construction, as it could not cooperate well with GS3C and GP3. The axenic GH2 exhibited no oil-degrading ability; however, it significantly promoted the degradation ability of the oil component-degrading bacteria, especially for degrading biorefractory polycyclic aromatic hydrocarbons. Axenic S. obliquus GH2, combined with the four bacteria mentioned above, formed an optimal algal-bacterial consortium. The artificial consortium demonstrated an elevated efficiency in degrading both aliphatic and aromatic hydrocarbons of crude oil.

Species differences for stereoselective metabolism of ethofumesate and its enantiomers in vitro

1. The stereoselective metabolism of ethofumesate (ETO) and its enantiomers in rabbit and rat liver microsomes have been studied by chiral high-performance liquid chromatography (HPLC) method. Two metabolites were detected in both liver microsomes in the presence of beta-nicotinamide adenine dinucleotide phosphate (NADPH). 2. The T(1/2) of (+)-ETO and (-)-ETO in rabbit liver microsomes were 12.2 and 4.7 min of rac-ETO and 25.9 and 6.7 of ETO enantiomers. However, the T(1/2) of (+)-ETO and (-)-ETO in rat liver microsomes were 5.3 and 5.9 min of rac-ETO and 7.8 and 10.6 of ETO enantiomers. The stereoselective selectivity is similar to the in vivo study. 3. After incubation of ETO enantiomers, stereoselectivity was present in the formation of ETO-OH enantiomer in rabbit liver microsomes, but stereoselectivity was not evident in rat liver microsomes. 4. There was no chiral inversion from the (+)-ETO to (-)-ETO or inversion from (-)-ETO to (+)-ETO in both rabbit and rat liver microsomes.

Molecular cloning and characterization of a T24-like protein in Echinococcus multilocularis

One tetraspanin, designated as E24, was cloned from a full-length enriched vector-capping cDNA library of Echinococcus multilocularis metacestode. The amino acid sequence and phylogenetic analysis suggested that E24 is a T24-like protein. The crucial, functional large extracellular loop (LEL) domain of E24 was expressed and characterized using a polyclonal antiserum by Western blot and immunohistochemistry. The results showed that anti-recombinant-E24 (anti-recE24) antibody can specifically recognize approximately 25 kDa recombinant protein and 25 kDa cyst-extracted antigen; the germinal layer of both the protoscolex-free and protoscolex-formed cysts were intensely labeled by immunofluorescent antibody. This study revealed that E24 is an antigenic, germinal layer-located protein of E. multilocularis metacestode, implying for its potential in diagnostic and vaccine development.

Detection and differentiation of ovine Theileria and Babesia by reverse line blotting in China

A reverse line blot (RLB) assay was developed for detection and specific identification of the different ovine Theileria and Babesia parasites. In a polymerase chain reaction (PCR), the hypervariable region 4 (V4 region) of the 18S ribosomal DNA gene was amplified with a set of general primers specific for members of the genera Theileria and Babesia. Meanwhile, specific oligonucleotide probes were designed and bound on membrane. After one single-PCR amplification, the amplified fragment was hybridized against different generic and species-specific probes. It was able to detect four species, i.e., Babesia motasi (Chengde, Lintan, Ningxian, Tianzhu), Babesia sp. (Kashi), Theileria luwenshuni (Lintan, Madang, Ningxian), Theileria uilenbergi (Longde, Zhangjiachuan) as defined previously. All probes bound to their respective target sequence only; therefore, no cross-reaction was observed, resulting in clear recognition of either individual strains, species, or groups in normal positive tests. Meanwhile, no signal was observed when ovine genomic DNA and water were used as a control, demonstrating that the signals are due to the presence of parasite DNA in the samples. Furthermore, the sensitivity of RLB could be considerably enhanced to detect a parasitemia level between10(-3)% and 10(-8)%. Finally, 117 samples from field were tested with RLB, PCR, and enzyme-linked immunosorbent assay (ELISA). The positive rate of RLB was higher than that of PCR and ELISA, and furthermore, RLB could determinate the species of piroplasms, the samples were infected with. Samples, 1,117, from five areas in Gannan Tibet Autonomous Region have been examined with RLB assay and compared with ELISA assay for corresponding samples. The results showed that the positive rate of RLB was higher than that of ELISA test obviously, and both T. luwenshuni and T. uilenbergi were widely distributed in these areas. RLB developed here could be used for differentiation of Babesia and Theileria infection and for epidemiological survey, which was difficult to achieve by classical methods. In conclusion, the RLB is a versatile technique for simultaneous detection and identification of all ovine piroplasms.

Experimental transmission of Theileria uilenbergi infective for small ruminants by Haemaphysalis longicornis and Haemaphysalis qinghaiensis

The experimental transmission of a recently designated Theileria uilenbergi pathogenic for sheep and goats in Northern China is described. Haemaphysalis qinghaiensis nymphs and adults developed from larvae and nymphs engorged on sheep infected with T. uilenbergi were able to respectively transmit the latter to sheep. However, when H. longicornis ticks picked up T. uilenbergi either at larval or nymphal, only the subsequent adult could transmit the parasites to sheep, the subsequent nymph could not transmit the parasites to sheep. This experiment suggested that the T. uilenbergi could be transmitted by at least two species of Haemaphysalis sp. ticks, H. longicornis and H. qinghaiensis, and the mode of transmission is stage to stage.

Small-scale expressed sequence tag analysis of Theileria uilenbergi: identification of a gene family encoding potential antigenic proteins

Recently, Theileria sp. (China) has been designated as T. luwenshuni[formerly Theileria sp. (China 1)] and T. uilenbergi[formerly Theileria sp. (China 2)]. A cDNA library of T. uilenbergi merozoites was constructed and subjected to random sequencing. Among the obtained sequences were three highly identical cDNA clones, indicating a gene family. Bioinformatic analyses indicated these genes contain signal peptides and encode potential immunogenic proteins. The presence of tandemly arranged and additional variants of these genes was shown. Analysis of one recombinantly expressed clone revealed immunoreactivity for serum from Theileria-infected animals. No cross-reaction with serum of T. lestoquardi-, Babesia motasi-, or Anaplasma ovis-infected animals was observed, indicating a potential antigen for development of serological diagnostic tools.

Experimental transmission of Theileria sp. (China 1) infective for small ruminants by Haemaphysalis longicornis and Haemaphysalis qinghaiensis

The experimental transmission of a recently identified new Theileria (China 1) species pathogenic for sheep and goats in northern China is described. Haemaphysalis qinghaiensis nymphs and adults developed from larvae and nymph engorged on sheep infected with Theileria sp. (China 1) were able to respectively transmit the Theileria sp. to splenectomized sheep. Meanwhile, H. longicornis nymphs and adults developed from larvae and nymphs engorged on sheep infected with Theileria sp. (China 1) were also able to respectively transmit this new Theileria sp. (China 1) to splenectomized sheep. These experiments suggested that the Theileria sp. (China 1) could be transmitted by at least two species of Haemaphysalis sp. ticks, H. longicornis and H. qinghaiensis, and the mode of transmission is stage to stage.

Sero-epidemiological surveillance of hypodermosis in yaks and cattle in north China by ELISA

A large-scale serological surveillance was conducted for hypodermosis in the north of China. A total of 4175 sera samples of yaks and cattle were collected from five provinces in north China that included Xinjiang, Inner Mongolia, Heilongjiang, Jiling and Gansu provinces, between 2001 and 2002, and were examined for anti-hypoderma antibody by ELISA. The results indicate that the naturally infested positive rates of Hypoderma spp. in the above provinces were 51.77%, 27.02%, 13.00%, 6.03% and 44.41%, respectively. These results suggest a significant warble fly population in the north of China. Positive sera were collected from infested cattle in Pingliang county of the Gansu province monthly between August 2001 and July 2002. These sera were used to evaluate the seasonal kinetics of anti-hypoderma antibody. The kinetics demonstrated that anti-hypoderma antibody was elevated from October to December. Thus, serological surveillances associated with low infestation rates and chemical therapy would best be performed from October to December in the region.

A comparison of small-subunit ribosomal RNA gene sequences of bovine Babesia species transmitted by Haemaphysalis spp. in China

The ribosomal small-subunit RNA gene sequences of six Chinese Babesia stocks infective to cattle, including a Babesia bigemina isolate, a B. bovis isolate, two B. ovata isolates, a Babesia sp. Wenchuan isolate and a B. major isolate, were compared and analyzed. The target DNA segment was amplified by polymerase chain reaction and the product ligated into the pGEM-T Easy vector for sequencing. The length of the 18S rRNA gene of all Babesia species involved in this study varied between 1,653 and 1,693 bp. The phylogenetic trees were inferred based on the 18S rRNA sequence of the Chinese isolates as well as other species of Babesia available in GenBank. The results showed that the B. ovata transmitted by Haemaphysalis longicornis and Babesia sp. Wenchuan isolate were confined to the same group as B. ovata Korea, with an identity among them of >96.5%, while B. major transmitted by H. punctata was situated in another branch, and identity with other bovine Babesia species was less than 92.5%. B. ovata should, therefore, be a valid species, differing from B. major according to the 18S rRNA gene sequence.

Cortisol increases Na(+)/K(+)-ATPase density in plasma membranes of gill chloride cells in the freshwater tilapia Oreochromis mossambicus

The effect of cortisol on Na(+)/K(+)-ATPase expression in the gill chloride cells of tilapia Oreochromis mossambicus was studied by immunocytochemistry at the light and electron microscope levels. One of three doses of cortisol (low, 125 mg kg(−1)food; middle, 375 mg kg(−1)food; high, 750 mg kg(−1) food) was administered via the food (at a ration of 1.5 % of body mass) and the fish were sampled after 5 days. Plasma osmolality and Na(+) levels were elevated in the middle- and high-dose groups, and plasma cortisol levels in the high-dose groups. Hematocrit values were not affected by the treatments. Opercular membrane chloride cell density increased by 94 % and 286 % in the middle- and high-dose fish, respectively, whereas the gill chloride cell frequency increased by up to 28 % maximally in the high-dose fish. Lamellar gill chloride cells were absent in the control and low-dose groups, but were observed in the middle- and high-dose groups. Cortisol increased the volume of the tubular membrane system in mature gill chloride cells. Quantification of immunogold-labelled Na(+)/K(+)-ATPase antigen (a 104 kDa protein species, as demonstrated by western blot) revealed that the high dose of cortisol increases the Na(+)/K(+)-ATPase density in the tubular system of chloride cells. This is the first direct evidence that cortisol not only increases chloride cell numbers but also Na(+)/K(+)-ATPase density in these cells.

Na(+)/K(+)-ATPase immunoreactivity in branchial chloride cells of Oreochromis mossambicus exposed to copper

Chloride cells were identified by Na(+)/K(+)-ATPase immunocytochemistry at the light and electron microscope levels in gills of freshwater tilapia Oreochromis mossambicus. Turnover of chloride cells was enhanced by exposing the fish to waterborne copper (3.2 micromol l(−)(1)) for 14 days, as indicated by a 38 % increase in cells expressing proliferating cell nuclear antigen (PCNA) relative to controls. The expression of PCNA was most marked in the central area of the filamental epithelium, from where the chloride cells are thought to originate and migrate. In control fish, chloride cells were associated exclusively with the filamental epithelium. In both controls and copper-exposed fish, two chloride cell populations were seen after Na(+)/K(+)-ATPase immunostaining. These probably represent subpopulations of newly emerged chloride cells: (1) strongly stained cells (mature chloride cells) in the filamental and lamellar epithelium and (2) weakly stained cells, identified by electron microscopy as apoptotic and necrotic chloride cells, mainly in the filamental epithelium. Absolute numbers of mature chloride cells fell, while necrotic and apoptotic chloride cell numbers increased, in copper-exposed fish. A strong correlation could be established for gill Na(+)/K(+)-ATPase specific activity and the number of strongly stained chloride cells in controls and copper-exposed fish and for Na(+)/K(+)-ATPase specific activity and total numbers of immunoreactive cells in copper-exposed fish owing to an increased incidence of weakly staining cells.

Metallothionein response in gills of Oreochromis mossambicus exposed to copper in fresh water

Freshwater Oreochromis mossambicus (tilapia) were exposed to 3.2 micromol/l Cu(NO(3))(2) in the water for up to 80 days, and copper (Cu) and immunoreactive metallothionein (irMT) were localized in the branchial epithelium. Cu was demonstrated in mucous cells (MC), chloride cells (CC), pavement cells (PC), respiratory cells (RC), and basal layer cells (BLC) via autometallography combined with alcian blue staining for MC and Na(+)-K(+)-ATPase immunostaining for CC and, on the basis of their location in the epithelium of PC, RC, and BLC. In control fish (water with Cu concentration </=90 nmol/l) incidentally irMT was observed in the area where progenitor cells of the branchial epithelia reside, as demonstrated by proliferating cell nuclear antigen staining. This was also the area where the first increase irMT expression of the Cu exposure was observed. After 2 days of exposure to Cu, irMT was found in CC and PC. From 5 days on, a pronounced irMT staining was observed in BLC of branchial epithelium, which then appeared to migrate and differentiate into mature CC, PC, and RC. We conclude that MT expression in mature CC, PC, and RC requires exposure to Cu in a earlier stage of development of these cells. Once expression is initiated in undifferentiated cells, MT remains expressed throughout the life cycle of the cell.