The venoms of sibling snakes may not be so similar

Daniela Miki Hatakeyama, PhD student, Interinstitutional Graduate Program in Biotechnology (Butantan Institute – IBU, University of São Paulo – USP, and Institute for Technological Research – IPT), and Laboratory of Herpetology, Butantan Institute, São Paulo, SP, Brazil.

Lídia Jorge Tasima, MSc student, Interinstitutional Graduate Program in Biotechnology (Butantan Institute – IBU, University of São Paulo – USP, and Institute for Technological Research – IPT), São Paulo, SP, Brazil.

Anita Mitico Tanaka-Azevedo, Scientific Researcher VI, Interinstitutional Graduate Program in Biotechnology (Butantan Institute – IBU, University of São Paulo – USP, and Institute for Technological Research – IPT), and Laboratory of Herpetology, Butantan Institute, São Paulo, SP, Brazil.

The article “Venom complexity of Bothrops atrox (common lancehead) siblings”, published in the Journal of Venomous Animals and Toxins including Tropical Diseases (vol. 26) in the “Snake venoms: from production to bioprospecting” collection, presents an analysis of the venoms of nine B. atrox siblings, either individually or mixed into pools of females and males. This species is medically important in the north region of South America because it is responsible for many cases of snakebites that results in sequelae and even death. The variability among individuals within the same species has been observed through the years and may be influenced by gender, age, geographical distribution, captivity, season, and diet. In addition to these factors, variation in venom composition and activities has been documented to occur in each specimen, which led the group to study the venom of genetically close individuals: nine B. atrox siblings. These snakes were born and raised in captivity, so they were submitted to a similar and controlled environment and feeding. Although some differences were expected, there were a few surprises in the results. The extensive study regarding snake venom variability is critical to a better understanding of this animal and to enhance the quality of antivenom, the only available treatment for snakebites.

This work was carried out in the Laboratory of Herpetology of the Butantan Institute. It started as a master’s degree project by the student Cesar Adolfo Bravo-Tobar in 2014-2015, under the supervision of Dr. Anita Mitico Tanaka-Azevedo, and was resumed in 2019 by Daniela Miki Hatakeyama and Lídia Jorge Tasima (also supervised by Dr. Anita Mitico Tanaka-Azevedo). The venoms were milked from nine B. atrox siblings born and raised in the serpentarium of the Laboratory of Herpetology. The venoms were individually subjected to tests to determine their composition and activities in vitro, which revealed a sex-related variation to a certain degree. With these results, venoms were mixed into pools of females and males that underwent a deeper compositional analysis and in vivo assays.

Adult specimen of Bothrop atrox. Image: Sávio S. Sant’Anna, reproduced with permission.

The compositional analysis showed some subtle differences more related to gender than individuals. The relative abundance of the protein families was surprisingly similar between female and male venom pools. Nevertheless, the female venom pool contained seven exclusive proteins that were not identified in the male venom pool. In regards to in vitro activities, individual variability was remarkable but some gender differences were also observed, especially with phospholipase A₂ (PLA₂) and coagulant activities. PLA₂s are enzymes involved in a diverse array of actions, such as edema induction, myotoxicity, neurotoxicity, induction and inhibition of platelet aggregation, cardiotoxicity, tissue damage, among others. Coagulant disorders are one of the main systemic effects caused by a snakebite of the genus Bothrops. Additionally, the male venom pool was more hemorrhagic than the female pool. These differences may influence the outcome of a snakebite depending on the gender of the animal that caused the accident and this may lead to different results in the treatment with antivenom. Finally, an immunorecognition assay was performed to observe the interaction of the antivenom produced at the Butantan Institute with the individual venoms and the pools. The Butantan Institute’s antibothropic serum is composed of antibodies raised in horses using a mixture of B. jararaca (50%), B. alternatus (12.5%), B. jararacussu (12.5%), B. moojeni (12.5%), and B. neuwiedi (12.5%) venoms. Even though B. atrox venom is not included in this venom cocktail for antivenom production, the interaction between antibodies and venom proteins was good, indicating a good recognition of the venom proteins by the antivenom.

As mentioned above, the variability of snake venoms is involved in many factors that may be genetically or environmentally related. For this reason, our group is constantly studying the venom of a large variety of snake species, analyzing their effects and neutralizing capabilities of the antibothropic serum. Besides, some venom proteins may display an interesting activity that can be investigated for further use as a drug. Therefore, the medical purpose of this study is not only related to the quality of the antivenom treatment, but also to the development of new potential drugs.

References

CHIPPAUX, J.P. et al. Snake venom variability: methods of study, results and interpretation. Toxicon [online]. 1991, vol. 29, no. 09, pp. 1279 – 1303  [viewed 18 December 2020]. https://doi.org/10.1016/0041-0101(91)90116-9. Available from: https://www.sciencedirect.com/science/article/abs/pii/0041010191901169?via%3Dihub

KINI, R. M. Excitement ahead: structure, function and mechanism of snake venom phospholipase A2 enzymes. Toxicon [online]. 2003, vol. 42, no. 8, pp. 827 – 840 [viewed 18 December 2020]. https://doi.org/10.1016/j.toxicon.2003.11.002. Aavailable from: https://doi.org/10.1016/j.toxicon.2003.11.002

Melgarejo AR. Serpentes peçonhentas do Brasil. In: Cardoso JL, França FO, Wen FH, Malaque CM, Haddad V Jr, editors. Animais peçonhentos no Brasil: biologia, clínica e terapêutica dos acidentes. São Paulo: Sarvier; 2003.

Warrell, D. A. Snakebites in Central and South America: epidemiology, clinical features, and clinical management. In: Campbell JA, Lamar WW, editors. The venomous reptiles of the western hemisphere. Vol 2. New York: Cornell University Press; 2004.

To read the article, acess

HATAKEYAMA, D. M. et al. Venom complexity of Bothrops atrox (common lancehead) siblings. J. Venom. Anim. Toxins incl. Trop. Dis [online]. 2020, vol. 26 [viewed 18 December 2020]. https://doi.org/10.1590/1678-9199-jvatitd-2020-0018. Available from: http://ref.scielo.org/hyvhzp

External links

Currículo Lattes – Anita Mitico Tanaka-Azevedo: http://lattes.cnpq.br/1402209642648415

Currículo Lattes – Daniela Miki Hatakeyama: http://lattes.cnpq.br/1721697241622035

Currículo Lattes – Lídia Jorge Tasima: http://lattes.cnpq.br/0825480555035374

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