What can be learned in the snake antivenom field from the developments in human plasma derived products?

Enhancing the Bothropic Antivenom through a Reverse Antivenomics Approach

Antivenoms are the only effective treatment for snakebite envenomation and have saved countless lives over more than a century. Despite their value, antivenoms present risks of adverse reactions. Current formulations contain a fraction of nonspecific antibodies and serum proteins. While new promising candidates emerge as the next generation of antivenoms, it remains clear that animal-derived antivenoms will still play a critical role for years to come. In this study, we improved the bothropic antivenom (BAv), by capturing toxin-specific antibodies through affinity chromatography using immobilized Bothrops jararaca venom toxins. This process produced an improved antivenom (iBAv) enriched in neutralizing antibodies and depleted of serum proteins. Proteomic analysis showed that iBAv was 87% depleted in albumin and 37-83% lower in other serum proteins compared to BAv. Functional evaluation demonstrated that iBAv had a 2.9-fold higher affinity for venom toxins by surface plasmon resonance and a 2.8-fold lower ED50 in vivo, indicating enhanced potency. Our findings indicate that enriching specific antibodies while depleting serum proteins reduces the total protein dose required and increases the potency of antivenom. Although technical and economic considerations remain for large-scale implementation, this affinity-enriched antivenom represents a significant advancement in improving antivenom efficacy against B. jararaca envenomations.

Progress and Challenges in the Field of Snakebite Envenoming Therapeutics

Snakebite envenoming kills and maims hundreds of thousands of people every year, especially in the rural settings of tropical regions. Envenomings are still treated with animal-derived antivenoms, which have prevented many lives from being lost but which are also medicines in need of innovation. Strides are being made to improve envenoming therapies, with promising efforts made toward optimizing manufacturing and quality aspects of existing antivenoms, accelerating research and development of recombinant antivenoms based on monoclonal antibodies, and repurposing of small-molecule inhibitors that block key toxins. Here, we review the most recent advances in these fields and discuss therapeutic opportunities and limitations for different snakebite treatment modalities. Finally, we discuss challenges related to preclinical and clinical evaluation, regulatory pathways, large-scale manufacture, and distribution and access that need to be addressed to fulfill the goals of the World Health Organization's global strategy to prevent and control snakebite envenoming.

Risk of stroke with antivenom usage after venomous snakebite in Taiwan: a population-based cohort study

BACKGROUND AND PURPOSE

Stroke is a rare complication of snakebites, but may lead to serious sequelae. We aimed to explore the relationship between venomous snakebite and the risk for acute stroke, in a nationwide population-based cohort study.

METHODS

This retrospective cohort study used claims data between 1 January 2000 and 31 December 2012, from the Taiwan National Health Insurance Research Database. The study included data of patients aged 18 years or older with venomous snakebite (n = 535), matched for propensity score with controls without venomous snakebite (n = 2140). The follow-up period was the duration from the initial diagnosis of venomous snakebite and administration of antivenom to the date of an acute stroke, or until 31 December 2013. The competing risk model was used to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of stroke, ischemic stroke and hemorrhagic stroke, after adjusting for demographic and other possible stroke risk factors.

RESULTS

The adjusted HR for the venomous snakebite group compared with the control group was 2.68 for hemorrhagic stroke (95% CI = 1.35-5.33). Stratified analysis showed that the older age group (>65 years old) had a higher risk of hemorrhagic stroke. A 2.72-fold significant increase in the risk for hemorrhagic stroke was observed following venomous snakebite with antivenom usage (95% CI = 1.41-5.26).

CONCLUSION

Venomous snakebite is associated with an increased risk of hemorrhagic stroke after the use of antivenom. Further study of the underlying mechanism is warranted.