Evaluation of alternative in vitro methods to the use of animals for in vivo tests in the study of snake venoms: principle of the 3R's

Abstract

According to the World Health Organization, snake envenoming is classified as a neglected disease that mainly affects vulnerable populations in tropical and subtropical countries. Although the main functions of snake venoms are to immobilize, paralyze and kill the prey in order to be able to ingest it safely, due to the complex composition of the venoms, there are several associated pathological effects. Most snake venoms induce damage to the local tissue of the bite, with the presence of myonecrosis, alteration of the integrity of blood vessels, formation of blisters, skin necrosis and also inflammation. In addition, snake poisoning also causes other systemic effects on its victims, such as: paralysis, which can involve respiratory muscle blockage, systemic hemorrhage, acute kidney injury and also affect hemostasis in several ways. Symptoms of envenoming vary according to the protein composition of the venom of different snakes. Such variations have a direct impact on the effectiveness of treatments for snake accidents, resulting in the need to produce different antivenoms against venoms of different species. Thus, the study of these variations and the quality control of these poisons has been the object of intense investigation. To this end, several biological activities of venoms are studied using both in vivo and in vitro methods. However, it is recognized that current in vivo tests require a large number of animals. Furthermore, they often do not correlate with human poisoning. There is an effort by the scientific community to follow the concept of the 3 R's (Reduce, Refine and Replace) in relation to animal tests, seeking the development of alternative methods for studies and quality control of poisons and antivenoms. Several alternative in vitro methods have been previously validated and approved to test the effects of different drugs, cosmetics and chemical products in general and, in the study of snake venom, several authors have already tested alternatives and have already found correlations between some in vivo tests with the in vitro. Thus, the present work intends to seek alternative methods to in vivo tests to evaluate the effects of venoms from pools of snakes used in the production of antivenoms from the Butantan Institute, as well as from venoms not used in the pools, such as Bothrops leucurus, Bothrops erythromelas and Bothrops atrox, mainly responsible for snake accidents in the Northeast and North of Brazil. (AU)