scholarly journals Kinetic Characterization and Inhibitor Screening of Pyruvate Kinase I From Babesia microti

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaomeng An ◽  
Long Yu ◽  
Sen Wang ◽  
Yangsiqi Ao ◽  
Xueyan Zhan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Pyruvate Kinase ◽  
Tannic Acid ◽  
Babesia Microti ◽  
Human Pathogens ◽  
Efficient Inhibitor ◽  
Attractive Therapeutic Target ◽  
Living Organisms ◽  
Human Babesiosis

The apicomplexan Babesia microti is a main pathogenic parasite causing human babesiosis, which is one of the most widely distributed tick-borne diseases in humans. Pyruvate kinase (PYK) plays a central metabolic regulatory role in most living organisms and catalyzes the essentially irreversible step in glycolysis that converts phosphoenolpyruvate (PEP) to pyruvate. Hence, PYK is recognized as an attractive therapeutic target in cancer and human pathogens such as apicomplexans. In this study, we cloned, expressed, and purified B. microti PYK I (BmPYKI). Western blotting illustrated that anti-rBmPYKI antibody could specifically recognize the native BmPYKI protein in the lysate of B. microti with a 54-kDa band, which is consistent with the predicted size. In addition, the enzymatic activity of the purified recombinant PYKI (rPYKI) was tested under a range of pH values. The results showed that the maximum catalytic activity could be achieved at pH 7.0. The saturation curves for substrates demonstrated that the Km value for PEP was 0.655 ± 0.117 mM and that for ADP was 0.388 ± 0.087 mM. We further investigated the effect of 13 compounds on rBmPYKI. Kinetic analysis indicated that six inhibitors (tannic acid, shikonin, apigenin, PKM2 inhibitor, rosiglitazone, and pioglitazone) could significantly inhibit the catalytic activity of PYKI, among which tannic acid is the most efficient inhibitor with an IC50 value 0.49 μM. Besides, four inhibitors (tannic acid, apigenin, shikonin, and PKM2 inhibitor) could significantly decrease the growth of in vitro-cultured B. microti with IC50 values of 0.77, 2.10, 1.73, and 1.15 μM. Overall, the present study provides a theoretical basis for the design and development of new anti-Babesia drugs.

scholarly journals The Global Emergence of Human Babesiosis

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1447
Author(s):  
Abhinav Kumar ◽  
Jane O'Bryan ◽  
Peter J. Krause
Keyword(s):  
United States ◽  
Wide Spectrum ◽  
The United States ◽  
Ixodid Ticks ◽  
Babesia Microti ◽  
Babesia Species ◽  
Human Pathogens ◽  
Endemic Disease ◽  
Predominant Species ◽  
Human Babesiosis

Babesiosis is an emerging tick-borne disease caused by intraerythrocytic protozoa that are primarily transmitted by hard-bodied (Ixodid) ticks and rarely through blood transfusion, perinatally, and organ transplantation. More than 100 Babesia species infect a wide spectrum of wild and domestic animals worldwide and six have been identified as human pathogens. Babesia microti is the predominant species that infects humans, is found throughout the world, and causes endemic disease in the United States and China. Babesia venatorum and Babesia crassa-like agent also cause endemic disease in China. Babesia divergens is the predominant species in Europe where fulminant cases have been reported sporadically. The number of B. microti infections has been increasing globally in recent decades. In the United States, more than 2000 cases are reported each year, although the actual number is thought to be much higher. In this review of the epidemiology of human babesiosis, we discuss epidemiologic tools used to monitor disease location and frequency; demographics and modes of transmission; the location of human babesiosis; the causative Babesia species in the Americas, Europe, Asia, Africa, and Australia; the primary clinical characteristics associated with each of these infections; and the increasing global health burden of this disease.

scholarly journals Babesia duncani as a model organism to study the development, virulence and drug susceptibility of intraerythrocytic parasites in vitro and in vivo

2021 ◽  
Author(s):  
Choukri Mamoun ◽  
Anasuya C. Pal ◽  
Isaline Renard ◽  
Pallavi Singh ◽  
Pratap Vydyam ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Molecular Mechanisms ◽  
Babesia Microti ◽  
Dual Model ◽  
Ideal System ◽  
Human Babesiosis

Hematozoa are a subclass of protozoan parasites that invade and develop within vertebrate red blood cells to cause the pathological symptoms associated with diseases of both medical and veterinary importance such as malaria and babesiosis. A major limitation in the study of the most prominent hematozoa, Plasmodium spp, the causative agents of malaria, is the lack of a broadly accessible mouse model to evaluate parasite infection in vivo as is the case for P. falciparum or altogether the lack of an in vitro culture and mouse models as is the case for P. vivax, P. malariae and P. ovale. Similarly, no in vitro culture system exists for Babesia microti, the predominant agent of human babesiosis. In this study, we show that human red blood cells infected with the human pathogen Babesia duncani continuously propagated in culture, as well as merozoites purified from parasite cultures, can cause lethal infection in immunocompetent C3H/HeJ mice. Furthermore, highly reproducible parasitemia and survival outcomes were established using specific parasite loads and different mouse genetic backgrounds. Using the combined in culturein mouse (ICIM) model of B. duncani infection, we demonstrate that current recommended combination therapies for the treatment of human babesiosis, while synergistic in cell culture, have weak potency in vitro and failed to clear infection or prevent death in mice. Interestingly, using the ICIM model, we identified two new endochin-like quinolone prodrugs, ELQ-331 and ELQ468, that alone or in combination with atovaquone are highly efficacious against B. duncani and B. microti. The novelty, ease of use and scalability of the B. duncani ICIM dual model make it an ideal system to study intraerythrocytic parasitism by protozoa, unravel the molecular mechanisms underlying parasite virulence and pathogenesis, and accelerate the development of innovative therapeutic strategies that could be translated to unculturable parasites and important pathogens for which an animal model is lacking.

scholarly journals BmGPAC, an Antigen Capture Assay for Detection of ActiveBabesia microtiInfection

2018 ◽  
Vol 56 (10) ◽  
Author(s):  
Jose Thekkiniath ◽  
Sara Mootien ◽  
Lauren Lawres ◽  
Benjamin A. Perrin ◽  
Meital Gewirtz ◽  
...  
Keyword(s):  
Acute Infection ◽  
Babesia Microti ◽  
Enzyme Linked Immunosorbent Assay ◽  
Animal Reservoir ◽  
Wild Mice ◽  
Content Type ◽  
Antigen Capture ◽  
Epidemiological Surveys ◽  
Human Babesiosis

ABSTRACTHuman babesiosis is an emerging zoonotic infectious disease caused by intraerythrocytic protozoan parasites of the genusBabesia. Most cases of human babesiosis are caused byBabesia microtiand often manifest in individuals over the age of 50 years or in patients with a compromised immune system. Patients who develop symptomaticB. microtiinfections usually experience months of asymptomatic infection after the acute infection has resolved. About one-fifth ofB. microti-infected adults never develop symptoms. These asymptomatically infected individuals sometimes donate blood and thus can transmitB. microtithrough blood transfusion. Current assays for detection of activeB. microtiinfections can be used to screen donor blood prior to transfusion, but they rely primarily on microscopy or PCR methods, which have sensitivity and technical limitations. Here we report the development of an antigen capture enzyme-linked immunosorbent assay (BmGPAC) based on a major secreted immunodominant antigen ofB. microti(BmGPI12/BmSA1), and we provide evidence that this assay is superior for detection of activeB. microtiinfections, compared to available microscopy methods and serological assays. The assay has been evaluated using supernatants ofB. microti-infected erythrocytes culturedin vitro, sera fromB. microti-infected laboratory mice, and sera from wild mice and human patients. Our data suggest that the BmGPAC assay is a reliable assay for detection of activeB. microtiinfections and is superior to real-time PCR and antibody assays for diagnosis of acuteB. microtiinfections, screening of the blood supply, and epidemiological surveys of humans and animal reservoir hosts.

scholarly journals Xanthohumol and Gossypol Are Promising Inhibitors against Babesia microti by In Vitro Culture via High-Throughput Screening of 133 Natural Products

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 613
Author(s):  
Jiaying Guo ◽  
Xiaoying Luo ◽  
Sen Wang ◽  
Lan He ◽  
Junlong Zhao
Keyword(s):  
Natural Products ◽  
High Throughput Screening ◽  
New Drugs ◽  
Babesia Microti ◽  
Severe Illness ◽  
Ic50 Values ◽  
Potential Inhibitors ◽  
Effective Drugs ◽  
Human Babesiosis

Human babesiosis caused by Babesia microti is an emerging threat for severe illness and even death, with an increasing impact worldwide. Currently, the regimen of atovaquone and azithromycin is considered as the standard therapy for treating human babesiosis, which, however, may result in drug resistance and relapse, suggesting the necessity of developing new drugs to control B. microti. In this regard, natural products are promising candidates for drug design against B. microti due to their active therapeutic efficacy, lower toxicity, and fewer adverse reactions to host. Here, the potential inhibitors against B. microti were preliminarily screened from 133 natural products, and 47 of them were selected for further screening. Gossypol (Gp) and xanthohumol (Xn) were finally shown to effectively inhibit the growth of B. microti with IC50 values of 8.47 μm and 21.40 μm, respectively. The cytotoxicity results showed that Gp and Xn were non-toxic to erythrocytes at a concentration below 100 μm. Furthermore, both of them were confirmed to be non-toxic to different types of cells in previous studies. Our findings suggest the potential of Gp and Xn as effective drugs against B. microti infection.

Current Challenges in the Development of Vaccines and Drugs Against Emerging Vector-borne Diseases

2019 ◽  
Vol 26 (16) ◽  
pp. 2974-2986 ◽  
Author(s):  
Kwang-sun Kim
Keyword(s):  
New Host ◽  
In Vivo Models ◽  
Vector Borne Diseases ◽  
Novel Drugs ◽  
Huge Impact ◽  
Tick Borne Disease ◽  
Vector Borne ◽  
Living Organisms

Vectors are living organisms that transmit infectious diseases from an infected animal to humans or another animal. Biological vectors such as mosquitoes, ticks, and sand flies carry pathogens that multiply within their bodies prior to delivery to a new host. The increased prevalence of Vector-Borne Diseases (VBDs) such as Aedes-borne dengue, Chikungunya (CHIKV), Zika (ZIKV), malaria, Tick-Borne Disease (TBD), and scrub typhus has a huge impact on the health of both humans and livestock worldwide. In particular, zoonotic diseases transmitted by mosquitoes and ticks place a considerable burden on public health. Vaccines, drugs, and vector control methods have been developed to prevent and treat VBDs and have prevented millions of deaths. However, development of such strategies is falling behind the rapid emergence of VBDs. Therefore, a comprehensive approach to fighting VBDs must be considered immediately. In this review, I focus on the challenges posed by emerging outbreaks of VBDs and discuss available drugs and vaccines designed to overcome this burden. Research into promising drugs needs to be upgraded and fast-tracked, and novel drugs or vaccines being tested in in vitro and in vivo models need to be moved into human clinical trials. Active preventive tactics, as well as new and upgraded diagnostics, surveillance, treatments, and vaccination strategies, need to be monitored constantly if we are to manage VBDs of medical importance.

scholarly journals Synergistic antibacterial combination of Lavandula latifolia Medik. essential oil with camphor

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nursenem Karaca ◽  
Görkem Şener ◽  
Betül Demirci ◽  
Fatih Demirci
Keyword(s):  
Staphylococcus Aureus ◽  
Essential Oil ◽  
Antibacterial Effect ◽  
Synergistic Effects ◽  
Pharmaceutical Formulations ◽  
Human Pathogens ◽  
Broth Microdilution ◽  
Antibacterial Effects ◽  
Lavandula Latifolia

AbstractCombination of various compounds and essential oils for pharmaceutical formulations withdraw attention. In this present study, it was aimed to evaluate the in vitro potential synergistic antibacterial effect of Lavandula latifolia (spike lavender) essential oil with camphor by using the checkerboard method against the human pathogens; Staphylococcus aureus and Listeria monocytogenes. Pharmacopoeia quality L. latifolia essential oil and racemic camphor were analyzed and verified by GC-FID and GC/MS, simultaneously. In vitro antibacterial activity of essential oil and camphor (MIC range: 0.16–20 mg/mL) and standard antimicrobial clarithromycin (MIC range: 0.125–16 μg/mL) were carried out by broth microdilution against S. aureus and L. monocytogenes standard strains, respectively. Resulting antibacterial effects were evaluated for their fractional inhibitory concentrations (FICs) as antagonistic, additive and synergistic effects. The analytical results showed that the major component of essential oil was linalool (45.2%) and 1,8-cineole (25.6%). Antibacterial effects of essential oil were determined as MIC 1.25–5 mg/mL. As a result of the experiments, L. latifolia essential oil–camphor combinations were identified as “synergistic (FIC ≤ 0.5), and additive (0.5 < FIC ≤ 1)” in the respective combinations, suggesting further evaluation for formulations for potential antimicrobial applications in food and pharmaceuticals.

scholarly journals The Physical Adsorption of Gelatinized Starch with Tannic Acid Decreases the Inhibitory Activity of the Polyphenol against α-Amylase

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1233
Author(s):  
Yueyi Wang ◽  
Shuangshuang Li ◽  
Fangting Bai ◽  
Junwei Cao ◽  
Lijun Sun
Keyword(s):  
Enzyme Inhibition ◽  
Tannic Acid ◽  
Inhibitory Activity ◽  
Adsorption Property ◽  
Physical Adsorption ◽  
Enzyme Active Site ◽  
Opposite Trend ◽  
Gelatinized Starch ◽  
The Difference

The effects of mixing orders of tannic acid (TA), starch, and α-amylase on the enzyme inhibition of TA were studied, including mixing TA with α-amylase before starch addition (order 1), mixing TA with pre-gelatinized starch before α-amylase addition (order 2) and co-gelatinizing TA with starch before α-amylase addition (order 3). It was found that the enzyme inhibition was always highest for order 1 because TA could bind with the enzyme active site thoroughly before digestion occurred. Both order 2 and 3 reduced α-amylase inhibition through decreasing binding of TA with the enzyme, which resulted from the non-covalent physical adsorption of TA with gelatinized starch. Interestingly, at low TA concentration, α-amylase inhibition for order 2 was higher than order 3, while at high TA concentration, the inhibition was shown with the opposite trend, which arose from the difference in the adsorption property between the pre-gelatinized and co-gelatinized starch at the corresponding TA concentrations. Moreover, both the crystalline structures and apparent morphology of starch were not significantly altered by TA addition for order 2 and 3. Conclusively, although a polyphenol has an acceptable inhibitory activity in vitro, the actual effect may not reach the expected one when taking processing procedures into account.

scholarly journals Targeting human Acyl-CoA:cholesterol acyltransferase as a dual viral and T cell metabolic checkpoint

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nathalie M. Schmidt ◽  
Peter A. C. Wing ◽  
Mariana O. Diniz ◽  
Laura J. Pallett ◽  
Leo Swadling ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Human Liver ◽  
Lipid Droplets ◽  
Ex Vivo ◽  
Functional Cure ◽  
Carcinogenic Activity ◽  
Attractive Therapeutic Target ◽  
Tcr Signalling

AbstractDetermining divergent metabolic requirements of T cells, and the viruses and tumours they fail to combat, could provide new therapeutic checkpoints. Inhibition of acyl-CoA:cholesterol acyltransferase (ACAT) has direct anti-carcinogenic activity. Here, we show that ACAT inhibition has antiviral activity against hepatitis B (HBV), as well as boosting protective anti-HBV and anti-hepatocellular carcinoma (HCC) T cells. ACAT inhibition reduces CD8+ T cell neutral lipid droplets and promotes lipid microdomains, enhancing TCR signalling and TCR-independent bioenergetics. Dysfunctional HBV- and HCC-specific T cells are rescued by ACAT inhibitors directly ex vivo from human liver and tumour tissue respectively, including tissue-resident responses. ACAT inhibition enhances in vitro responsiveness of HBV-specific CD8+ T cells to PD-1 blockade and increases the functional avidity of TCR-gene-modified T cells. Finally, ACAT regulates HBV particle genesis in vitro, with inhibitors reducing both virions and subviral particles. Thus, ACAT inhibition provides a paradigm of a metabolic checkpoint able to constrain tumours and viruses but rescue exhausted T cells, rendering it an attractive therapeutic target for the functional cure of HBV and HBV-related HCC.

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