Phenotypic dichotomy in Crotalus durissus ruruima venom and potential consequences for clinical management of snakebite envenomations

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Colombini, Monica ; Rocha, Anderson M. ; Freitas-de-Sousa, Luciana A. ; Chaves, Alison F. A. ; Serrano, Solange M. T. ; Souza, Vinicius C. ; Viala, Vincent L. ; Junqueira-Azevedo, Inacio L. M. ; Cerni, Felipe A. ; Sartim, Marco A. ; Sachett, Jacqueline A. G. ; Monteiro, Wuelton M. ; Grazziotin, Felipe G. ; Wen, Fan Hui ; Pucca, Manuela B. ; Moura-da-Silva, Ana M.

• Document type: Journal article
• Source: PLoS Neglected Tropical Diseases; v. 19, n. 8, p. 28-pg., 2025-08-01.

Abstract

Background Phenotypic polymorphism in rattlesnake venoms is well-documented, with a dichotomy between hemorrhagic (Type I) and neurotoxic (Type II) venoms. In South America, the Type II phenotype is predominant; however, evidence of Type I venom in Crotalus durissus ruruima raises concerns about the efficacy of the Crotalus antivenom, which is prepared only with Type II venoms. Consequently, the Bothrops-Crotalus antivenom has been proposed as an alternative treatment for envenomation by Type I venoms.Methodology/Principal findings This study characterizes the dichotomy of C. d. ruruima venom by analyzing the structure of isoforms differentially expressed in Type I and Type II venoms, assessing their biological activities, and evaluating the implications for snakebite clinical management in Roraima State (northern Brazil). Four toxins were differentially expressed between Type I and Type II venoms: two PIII-class SVMPs, predominantly found in Type I venoms, associated with proteolytic and hemorrhagic activity; and two PLA2s, corresponding to Crotoxin A and B chains, prevalent in Type II venoms and related to elevated phospholipase A2 activity, myotoxicity, and increased lethality. The structure of Crotoxin chains was well conserved compared to C. d. terrificus Crotoxin. However, the SVMP sequences exhibited multiple substitutions in functional and immunoreactive regions compared to Bothropasin, resulting in low hemorrhagic activity and limited reactivity/neutralization by the Bothrops antivenom. Conversely, the Crotalus antivenom reacted with high antibody titer and neutralized all activities of both venom subtypes, except for the low hemorrhagic activity induced by Type I venoms.Conclusions/Significance The efficacy of Bothrops antivenom in snakebites caused by rattlesnakes with Type I venoms remains uncertain. We advocate for a clinical study in Roraima to assess patient outcomes and benefits of Bothrops-Crotalus versus Crotalus antivenoms for these accidents. Meanwhile, administering Bothrops-Crotalus antivenom may be acceptable; however, caution is needed regarding the use of heterologous Bothrops antibodies, which have limited efficacy in treating Crotalus envenomation. (AU)

• FAPESP's process: 13/07467-1 - CeTICS - Center of Toxins, Immune-Response and Cell Signaling
• Grantee: Hugo Aguirre Armelin
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 20/12317-2 - Proteomic analysis of the systemic effects of Bothrops jararaca venom in a murine model
• Grantee: Alison Felipe Alencar Chaves
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/10344-8 - Advances in snake bite treatment: preclinical and clinical studies, alternative treatments and decentralization
• Grantee: Ana Maria Moura da Silva
• Support Opportunities: Regular Research Grants
• FAPESP's process: 22/12660-4 - Recovering, modernizing and expanding the collection of herpetology at Butantan Institute through integrative studies on systematics and evolution of neotropical snakes
• Grantee: Felipe Gobbi Grazziotin
• Support Opportunities: BIOTA-FAPESP Program - Young Investigators Grants
• FAPESP's process: 16/50127-5 - Dimensions US-BIOTA São Paulo: scales of biodiversity: integrated studies of snake venom evolution and function across multiple levels of diversity
• Grantee: Inácio de Loiola Meirelles Junqueira de Azevedo
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants