ricin toxin
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2021 ◽  
Vol 22 (22) ◽  
pp. 12345
Author(s):  
Anita Sapoznikov ◽  
Yoav Gal ◽  
Yentl Evgy ◽  
Moshe Aftalion ◽  
Shahaf Katalan ◽  
...  

Ricin toxin isolated from the castor bean (Ricinus communis) is one of the most potent and lethal molecules known. While the pathophysiology and clinical consequences of ricin poisoning by the parenteral route, i.e., intramuscular penetration, have been described recently in various animal models, the preceding mechanism underlying the clinical manifestations of systemic ricin poisoning has not been completely defined. Here, we show that following intramuscular administration, ricin bound preferentially to the vasculature in both mice and swine, leading to coagulopathy and widespread hemorrhages. Increased levels of circulating VEGF and decreased expression of vascular VE-cadherin caused blood vessel impairment, thereby promoting hyperpermeability in various organs. Elevated levels of soluble heparan sulfate, hyaluronic acid and syndecan-1 were measured in blood samples following ricin intoxication, indicating that the vascular glycocalyx of both mice and swine underwent extensive damage. Finally, by using side-stream dark field intravital microscopy imaging, we determined that ricin poisoning leads to microvasculature malfunctioning, as manifested by aberrant blood flow and a significant decrease in the number of diffused microvessels. These findings, which suggest that glycocalyx shedding and microcirculation dysfunction play a major role in the pathology of systemic ricin poisoning, may serve for the formulation of specifically tailored therapies for treating parenteral ricin intoxication.


2021 ◽  
Vol 12 ◽  
Author(s):  
Mingxin Dong ◽  
Xiaohao Zhang ◽  
Haotian Yu ◽  
Yan Wang ◽  
Ying Chang ◽  
...  

Increasing studies have concentrated on investigating circular RNAs (circRNAs) as pivotal regulators in the progression of numerous diseases and biological processes and abundant evidence shows that circRNAs are participated in the regulation of innate immune responses. Several studies showed that Ricin Toxin (RT) could induce inflammatory injury. There was no research on the particular functions and underlying mechanisms of circRNAs in RT-induced inflammation. In this study, RNA sequencing performed on RT-treated and normal RAW264.7 macrophage cells was used to investigated the differentially expressed circRNAs. Based on the dataset, the expression of circEpc1 (mmu_circ_0,000,842) was identified higher in RT-treated cells. Moreover, gain-and-loss function assays showed that circEpc1 function as a promoter in RT-induced inflammation in vivo and in vitro. Mechanistically, circEpc1 acted as a miR-5114 sponge to relieve the suppressive effect of miR-5114 on its target NOD2 and thereby activating NF-κB and MAPK signaling pathways. Our results illuminated a link between RT-induced inflammation and the circEpc1 regulatory loop and provided novel insight into the functions of circRNA in innate immune, which may emerge as a potential target in immunotherapy to control the RT-induced inflammatory injury.


Toxicon ◽  
2021 ◽  
Author(s):  
Kaikai Yu ◽  
Haotian Yu ◽  
Yingshuang Wang ◽  
Mingxin Dong ◽  
Yan Wang ◽  
...  
Keyword(s):  

2021 ◽  
Author(s):  
Hayley Novak ◽  
Jennifer Doering ◽  
Dylan Ehrbar ◽  
Oreola Donini ◽  
Nicholas J. Mantis

ABSTRACTThe development of vaccines against biothreat toxins like ricin (RT) is considered an integral component of the United States national security efforts. RiVax® is a thermostable, lyophilized RT subunit vaccine adsorbed to aluminum salt adjuvant intended for use by military personnel and first responders. Phase 1 studies indicated that RiVax is safe and immunogenic, while a three dose, intramuscular vaccination regimen in non-human primates elicited protection against lethal dose RT challenge by aerosol. Here we investigated, in a mouse model, the durability of RiVax-induced antibody responses and corresponding immunity to lethal dose RT challenge. Groups of mice were subcutaneously administered 3 or 1 μg of RiVax on days 0 and 21 and challenged with 10 × LD50 RT by injection at six different intervals over the course of twelve months. Serum antibody titers and epitope-specific competition assays were determined prior to each challenge. We report that the two-dose, 3 μg regimen conferred near complete protection against RT challenge on day 35 and complete protection thereafter (challenge days 65, 95, 125, 245, and 365). The two-dose, 3 μg regimen was superior to the 1 μg regimen as revealed by slight differences in survival and morbidity scores (e.g., hypoglycemia, weight loss) on challenge days 35 and 365. In separate experiments, a single 3 μg RiVax vaccination proved only marginally effective at eliciting protective immunity to RT, underscoring the necessity of a prime-boost regimen to achieve full and long-lasting protection against RT.IMPORTANCERicin toxin (RT) is a notorious biothreat, as exposure to even trace amounts via injection or inhalation can induce organ failure and death within a matter of hours. In this study, we advance the preclinical testing of a candidate RT vaccine known as RiVax®. RiVax is a recombinant non-toxic derivative of RT’s enzymatic subunit that has been evaluated for safety in Phase I clinical trials and efficacy in a variety of animal models. We demonstrate that two doses of RiVax is sufficient to protect mice from lethal dose RT challenge for up to one year. We describe kinetics and other immune parameters of the antibody response to RiVax and discuss how these immune factors may translate to humans.


2021 ◽  
Author(s):  
Mingxin Dong ◽  
Xiaohao Zhang ◽  
Haotian Yu ◽  
Yan Wang ◽  
Ying Chang ◽  
...  

Abstract Background: Increasing studies have concentrated on investigating circular RNAs (circRNAs) as pivotal regulators in the progression of numerous diseases and biological processes and abundant evidence shows that circRNAs are participated in the regulation of innate immune responses. Several studies showed that Ricin Toxin (RT) could induce inflammatory injury. There was no research on the particular functions and underlying mechanisms of circRNAs in RT-induced inflammation. Results: In this study, RNA sequencing performed on RT-treated and normal RAW264.7 macrophage cells was used to investigated the differentially expressed circRNAs. Based on the dataset, the expression of circEpc1 (mmu_circ_0000842) was identified higher in RT-treated cells. Moreover, gain-and-loss function assays showed that circEpc1 function as a promoter in RT-induced inflammation in vivo and in vitro. Mechanistically, circEpc1 acted as a miR-5114 sponge to relieve the suppressive effect of miR-5114 on its target NOD2 and thereby activating NF-κB and MAPK signaling pathways. Conclusions: Our results illuminated a link between RT-induced inflammation and the circEpc1 regulatory loop and provided novel insight into the functions of circRNA in innate immune, which may emerge as a potential target in immunotherapy to control the RT-induced inflammatory injury.


2021 ◽  
Vol 23 (2) ◽  
pp. 219-228
Author(s):  
Vadim A. Myasnikov ◽  
Alexander V. Stepanov ◽  
Olga A. Miteva ◽  
Alexander S. Nikishin ◽  
Alexander S. Gogolevsky ◽  
...  

This article reviews the current understanding of the mechanism of action of the toxin, the clinical effects of ricin and abrin intoxication and how these relate to current and continuing prospects for vaccine development. The threat of bioterrorism worldwide has accelerated the demand for the development of therapies and vaccines against the ribosome-inactivating proteins. The diverse and unique nature of these toxins poses a challenge to vaccinologists. This paper will review the mechanism of toxicity and vaccines development to protect against the highly toxic plant-derived ribosomal toxins. Vaccine development is further complicated by the fact that as bioterrorism agents, abrin and ricin would most likely be disseminated as aerosols supplies. Our understanding of the mechanisms by which these toxins cross mucosal surfaces, and importance of mucosal immunity in preventing toxin uptake is only rudimentary. Research is now aimed at developing recombinant, attenuated vaccines based on a detailed understanding of the molecular mechanisms by which these toxins function. The evolution of the development of specific immunoprophylaxis of acute ricin poisoning from native toxoid to genetically engineered subunit vaccines based on the method of targeted mutagenesis is traced. The past several years have seen major advances in the development of a safe and efficacious ricin toxin vaccine. These vaccines are discussed in the context of the toxicity and structure of ricin. In this review we summarize ongoing efforts to leverage recent advances in the design and use of vaccines.


2021 ◽  
pp. 1-7
Author(s):  
Reut Falach ◽  
Michael Goldvaser ◽  
Pinchas Halpern ◽  
Amir Rosner ◽  
Anita Sapoznikov ◽  
...  

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1093
Author(s):  
Grace Q. Chen ◽  
Kumiko Johnson ◽  
Tara J. Nazarenus ◽  
Grisel Ponciano ◽  
Eva Morales ◽  
...  

Seeds of castor (Ricinus communis) are enriched in oil with high levels of the industrially valuable fatty acid ricinoleic acid (18:1OH), but production of this plant is limited because of the cooccurrence of the ricin toxin in its seeds. Lesquerella (Physaria fendleri) is being developed as an alternative industrial oilseed because its seeds accumulate lesquerolic acid (20:1OH), an elongated form of 18:1OH in seed oil which lacks toxins. Synthesis of 20:1OH is through elongation of 18:1OH by a lesquerella elongase, PfKCS18. Oleic acid (18:1) is the substrate for 18:1OH synthesis, but it is also used by fatty acid desaturase 2 (FAD2) and FAD3 to sequentially produce linoleic and linolenic acids. To develop lesquerella that produces 18:1OH-rich seed oils such as castor, RNA interference sequences targeting KCS18, FAD2 and FAD3 were introduced to lesquerella to suppress the elongation and desaturation steps. Seeds from transgenic lines had increased 18:1OH to 1.1–26.6% compared with that of 0.4–0.6% in wild-type (WT) seeds. Multiple lines had reduced 18:1OH levels in the T2 generation, including a top line with 18:1OH reduced from 26.7% to 19%. Transgenic lines also accumulated more 18:1 than that of WT, indicating that 18:1 is not efficiently used for 18:1OH synthesis and accumulation. Factors limiting 18:1OH accumulation and new targets for further increasing 18:1OH production are discussed. Our results provide insights into complex mechanisms of oil biosynthesis in lesquerella and show the biotechnological potential to tailor lesquerella seeds to produce castor-like industrial oil functionality.


Life ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 405
Author(s):  
George Oliveira ◽  
José Maurício Schneedorf

International authorities classify the ricin toxin, present in castor seeds, as a potential agent for use in bioterrorism. Therefore, the detection, identification, and characterization of ricin are considered the first actions for its risk assessment during a suspected exposure, parallel to the development of therapeutic and medical countermeasures. In this study, we report the kinetic analysis of electro-oxidation of adenine released from hsDNA by the catalytic action of ricin by square wave voltammetry. The results suggest that ricin-mediated adenine release exhibited an unusual kinetic profile, with a progress curve controlled by the accumulation of the product and the values of the kinetic constants of 46.6 µM for Km and 2000 min−1 for kcat, leading to a catalytic efficiency of 7.1 × 105 s−1 M−1.


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