Effect of heating on the toxic, immunogenic and immunosuppressive activities of Crotalus durissus terrificus venom

Effect of gamma-irradiated honey bee venom on blood parameter and histopathological observations of liver and kidney in a mice animal model

Honey bee venom is a valuable product with a wide range of biological effects, whose use is rapidly increasing in apitherapy. In this study, the effect of gamma-irradiated honey bee venom (doses of 0, 2, 4, 6, and 8 kGy, volume of 0.1 ml, and concentration of 0.2 mg/ml) was evaluated on median lethal dose (LD50) determinations, liver and kidney histology, biochemical marker level, and serum protein analyses. Hence, the LD50 induced by the honey bee venom irradiated at 4, 6, and 8 kGy was increased, compared with the one at 0 and 2 kGy. Normal histology was observed in the liver and kidney of the mice receiving the honey bee venom irradiated at 4, 6, and 8 kGy. The serum levels of alanine aminotransferase (ALT) and all serum proteins were reduced at 4, 6, and 8 kGy compared with 0 and 2 kGy. Therefore, gamma irradiation at 4, 6, and 8 kGy had no negative effect on LD50, liver and kidney tissues, ALT, and serum protein levels by decreasing the allergen compounds of the honey bee venom.

Effect of gamma-irradiated honey bee venom on gene expression of inflammatory and anti-inflammatory cytokines in mice

In this study, the effect of gamma-irradiated honey bee venom (doses of 0, 2, 4, 6, and 8 kGy, volume of 0.1 ml and concentration of 0.2 mg/ml) was evaluated on the reduction of allergen compounds and the gene expression of inflammatory and anti-inflammatory cytokines in mice. Hence, edema activity induced by the bee venom irradiated at 4, 6, and 8 kGy was reduced, compared with the control group and that irradiated at 2 kGy. In contrast, the paw edema induced by the bee venom irradiated at 8 kGy increased, compared with 4 and 6 kGy. At all the time periods, there was a significant decrease in the gene expression of interferon gamma (IFN-γ), interleukin 6 (IL-6), and interleukin 10 (IL-10) in the bee venoms irradiated at 4, 6, and 8 kGy, compared with the control group and that irradiated at 2 kGy. In contrast, there was an increase in the gene expression of IFN-γ and IL-6 in the bee venom irradiated at 8 kGy, compared with those irradiated at 4 and 6 kGy. Therefore, gamma irradiation at 4 and 6 kGy reduced the gene expression of cytokines at each time period by decreasing the allergen compounds of honey bee venom.

Immunorecognition and Neutralization of Crotalus durissus cumanensis Venom by a Commercial Antivenom Produced in Colombia

In Colombia, on average 2.9% of the nearly 5600 snakebite events that occur annually involve the rattlesnake Crotalus durissus cumanensis. The envenomation by this snake is mainly characterized by neurotoxicity and the main toxin is crotoxin (~64.7% of the total venom). The Instituto Nacional de Salud (INS) produces a polyvalent antivenom aimed at the treatment of bothropic, crotalid, and lachesic envenomations; nonetheless, its immune reactivity profile and neutralizing capacity over biological activities of the C. d. cumanensis venom has been poorly evaluated. In this sense, the study aims: (1) to describe an in-depth exploration of its immunoreactivity through second-generation antivenomics and HPLC fraction-specific ELISA immunoprofiles; and (2) to evaluate the neutralization pattern of the rattlesnake venom in vitro and in vivo biological activities. The results obtained showed a variable recognition of crotoxin subunits, in addition to a molecular mass-dependent immunoreactivity pattern in which the disintegrins were not recognized, and snake venom metalloproteinases and L-amino acid oxidases were the most recognized. Additionally, a high neutralization of proteolytic and coagulant activities was observed, but not over the PLA₂ activity. Further, the median effective dose against C. d. cumanensis venom lethality was 962 μL of antivenom per mg of venom. In conclusion, (1) the antivenom recognition over the crotoxin and the disintegrins of the C. d. cumanensis should be improved, thus aiming upcoming efforts for the exploration of new techniques and approaches in antivenom production in Colombia, and (2) the neutralization activity of the antivenom seems to follow the molecular mass-dependent recognition pattern, although other explanations should be explored.

A Quest for a Universal Plasma-Derived Antivenom Against All Elapid Neurotoxic Snake Venoms

This review describes the research aimed at the development of universal antivenom against elapid neurotoxic snake venoms. The antivenoms produced in Thailand in the 1980s were of low potency, especially against the elapid venoms. This was thought to be due to the low immunogenicity of the α-neurotoxins, which are the most lethal toxins in these venoms. Comparisons of various α-neurotoxin conjugates and polymers, and also different immunological adjuvants, showed that the adjuvant used is the major determinant in the antibody response in horses. The potent Freund's adjuvant was not used due to its severe local side-effect in horses. Therefore, a novel immunization protocol termed 'low dose, low volume multi-site' was developed for use in horses. This immunization protocol has led to the production of highly potent monospecific antivenoms against several elapid and viperid venoms, and two potent polyspecific antivenoms, one against 4 neurotoxic and another against 3 hematotoxic venoms. The immunization protocol has also led to other improvements in antivenom production including: several fold increases in antiserum potency, a reduction in the time required to reach therapeutically useful antibody titers, a 90% reduction in the amount of venom used, and 100% of the horses responding to the immunization program. This development is partly responsible for significant decrease in the Thailand's annual snakebite death toll from a few dozens to mostly nil in recent years. Finally, a simple and novel immunization strategy, using a 'diverse toxin repertoire' composed of numerous elapid toxin fractions as immunogen, was proposed and tested. This immunization procedure has resulted in the successful production of a widely paraspecific antiserum against at least 36 neurotoxic venoms of 28 species encompassing 10 genera and from 20 countries on four continents, and possibly against all elapid venoms with α-neurotoxins as the lethal toxins. These results indicate that, with optimizations of the composition of the 'diverse toxin repertoire', the immunization scheme and antibody fractionation to increase the antivenom neutralizing potency, an effective universal antivenom against the neurotoxic elapid snakes of the world can be produced.

Paratrygon aiereba irradiated anti-mucus serum reduce edematogenic activity induced in experimental model

Accidents by freshwater stingrays are common in northern Brazil, there is no specific therapy for high morbidity and local tissue destruction. The irradiation of venoms and toxins by ionizing radiation has been used to produce appropriate immunogens for the production of antisera. We planned to study the efficacy of stinging mucus irradiation in the production of antisera, with serum neutralization assays of edematogenic activity and quantification of cytokines performed in animal models of immunization with native and irradiated mucus of Paratrygon aiereba, a large freshwater stingray. Antiserum potency and its cross-reactivity with mucus from other freshwater stingrays were detected by ELISA. Immunization models demonstrated the ability to stimulate a strong humoral response with elevated levels of serum IgG detectable by ELISA, and both native and irradiated mucus were immunogenic and capable of recognizing mucus proteins from other freshwater neotropical stingrays. Mucus P. aiereba causes cellular and humoral adaptive immune responses in cells of immunized mice producing antibodies and cytokines such as TNF-α, IL-6 and IL-17. Rabbit antisera immunized with mucus from P. aiereba irradiated at 2 kGy showed a significant reduction of mucus-induced edematogenic activity in mice. Our data suggest that the use of antisera against freshwater stingray mucus show the possibility of specific therapy for these accidents.

Engineered protein containing crotoxin epitopes induces neutralizing antibodies in immunized rabbits

Crotoxin (Ctx) is the main lethal component of Crotalus durissus terrificus venom. It is a neurotoxin, composed of two subunits associated by noncovalent interactions, the non-toxic acid subunit (CA), named Crotapotin, and the basic subunit (CB), with phospholipase A₂ (PLA₂) activity. Employing the SPOT synthesis technique, we determined two epitopes located in the C-terminal of each Ctx subunit. In addition, 3 other epitopes were mapped in different regions of Ctx using subcutaneous spot implants surgically inserted in mice. All epitopes mapped here were expressed together as recombinant multi-epitopic protein (rMEPCtx), which was used to immunize New Zealand rabbits. Anti-rMEPCtx rabbit serum cross-reacted with Ctx and crude venoms from C. d. terrificus, Crotalus durissus ruruima, Peruvian C. durissus and Bothrops jararaca (with lower intensity). Furthermore, anti-rMEPCtx serum was able to neutralize Ctx lethal activity. As the recombinant multiepitopic protein is not toxic, it can be administered in larger doses without causing adverse effects on the immunized animals health. Therefore, our work evidences the identification of neutralizing epitopes of Ctx and support the use of recombinant multiepitopic proteins as an innovation to immunotherapeutics production.

Immunotherapeutic potential of Crotoxin: anti-inflammatory and immunosuppressive properties

For the past 80 years, Crotoxin has become one of the most investigated isolated toxins from snake venoms, partially due to its major role as the main toxic component in the venom of the South American rattlesnake Crotalus durissus terrificus. However, in the past decades, progressive studies have led researchers to shift their focus on Crotoxin, opening novel perspectives and applications as a therapeutic approach. Although this toxin acts on a wide variety of biological events, the modulation of immune responses is considered as one of its most relevant behaviors. Therefore, the present review describes the scientific investigations on the capacity of Crotoxin to modulate anti-inflammatory and immunosuppressive responses, and its application as a medicinal immunopharmacological approach. In addition, this review will also discuss its mechanisms, involving cellular and molecular pathways, capable of improving pathological alterations related to immune-associated disorders.

Innovative Immunization Strategies for Antivenom Development

Snakes, scorpions, and spiders are venomous animals that pose a threat to human health, and severe envenomings from the bites or stings of these animals must be treated with antivenom. Current antivenoms are based on plasma-derived immunoglobulins or immunoglobulin fragments from hyper-immunized animals. Although these medicines have been life-saving for more than 120 years, opportunities to improve envenoming therapy exist. In the later decades, new biotechnological tools have been applied with the aim of improving the efficacy, safety, and affordability of antivenoms. Within the avenues explored, novel immunization strategies using synthetic peptide epitopes, recombinant toxins (or toxoids), or DNA strings as immunogens have demonstrated potential for generating antivenoms with high therapeutic antibody titers and broad neutralizing capacity. Furthermore, these approaches circumvent the need for venom in the production process of antivenoms, thereby limiting some of the complications associated with animal captivity and venom collection. Finally, an important benefit of innovative immunization approaches is that they are often compatible with existing antivenom manufacturing setups. In this review, we compile all reported studies examining venom-independent innovative immunization strategies for antivenom development. In addition, a brief description of toxin families of medical relevance found in snake, scorpion, and spider venoms is presented, as well as how biochemical, bioinformatic, and omics tools could aid the development of next-generation antivenoms.

New immunization protocol to produce crotalic antivenom combining Crotalus durissus terrificus venom and its PLA2

Antivenoms are usually obtained by animal immunization with successive inoculations of increasing sublethal amounts of venom, which may impair the animal health. The high lethality of venom requires prolonged immunization plans with small amounts of venom. Thus, we propose an alternative plan that includes a pre-immunization of the animal with phospholipase A2, the main crotoxin component, which is responsible for the whole venom lethality. For comparison, three different immunization schemes were designed: high dose protocol (HDP; 0.5-27 mg of venom), low dose protocol (LDP; 0.1-7 mg of venom) and Mix protocol (MP; preimmunization 0.1-1.2 mg of crotalic PLA2, and then 4.5-8 mg of venom). Antibody titers were determined by ELISA, in blood plasma obtained from the marginal vein of the ear. The neutralizing ability of the different sera obtained by all protocols (HDS, LDS and MS) was tested against the most important pharmacological activities of whole venom: PLA2 activity, myotoxicity, thrombin like activity and lethality. MS showed the best neutralizing efficacy and at the same time, it was obtained by an immunization protocol that takes account of animal health care, since it requires low quantities of venoms in comparison to traditional protocols.

Differential Effects of Naja naja atra Venom on Immune Activity

Previous studies reported that Naja naja atra venom (NNAV) inhibited inflammation and adjuvant arthritis. Here we investigated the role of NNAV in regulation of immune responses in mice. Oral administration of NNAV to normal mice showed significant increase in natural killer cell activity, B lymphocyte proliferation stimulated by lipopolysaccharides, and antibody production in response to sheep red blood cells. Meanwhile, NNAV markedly decreased T lymphocyte proliferation stimulated by concanavalin A, arrested the cell cycle at G₀/G₁ phase, and suppressed CD4 and CD8 T cell divisions. Furthermore, NNAV inhibited the dinitrofluorobenzene-induced delayed-type hypersensitivity reaction. This modulation of immune responses may be partly attributed to the selective increase in Th1 and Th2 cytokines (IFN-γ, IL-4) secretion and inhibition of Th17 cytokine (IL-17) production. In dexamethasone-induced immunosuppressed mice, NNAV restored the concentration of serum IgG and IgM, while decreasing the percentage of CD4 and CD8 T-cell subsets. These results indicate that NNAV enhances the innate and humoral immune responses while inhibiting CD4 Th17 and CD8 T cell actions, suggesting that NNAV could be a potential therapeutic agent for autoimmune diseases.