Abstract Background Snakebite treatment requires administration of an appropriate antivenom that should contain antibodies capable of neutralizing the venom. To achieve this goal, antivenom production must start from a suitable immunization protocol and proper venom mixtures. In Brazil, antivenom against South American rattlesnake (Crotalus durissus terrificus) bites is produced by public institutions based on the guidelines defined by the regulatory agency of the Brazilian Ministry of Health, ANVISA. However, each institution uses its own mixture of rattlesnake venom antigens. Previous works have shown that crotamine, a toxin found in Crolatus durissus venom, shows marked individual and populational variation. In addition, serum produced from crotamine-negative venoms fails to recognize this molecule. Methods In this work, we used an antivenomics approach to assess the cross-reactivity of crotalic antivenom manufactured by IVB towards crotamine-negative venom and a mixture of crotamine-negative/crotamine-positive venoms. Results We show that the venom mixture containing 20% crotamine and 57% crotoxin produced a strong immunogenic response in horses. Antivenom raised against this venom mixture reacted with most venom components including crotamine and crotoxin, in contrast to the antivenom raised against crotamine-negative venom. Conclusions These results indicate that venomic databases and antivenomics analysis provide a useful approach for choosing the better venom mixture for antibody production and for the subsequent screening of antivenom cross-reactivity with relevant snake venom components.

This paper reports the preliminary results of two years of herpetogeographic studies in the region called «Grande Porto Alegre» at its northern portion. The physiognomy shows, at North, slopes of the Brazilian Southern Plateau, more or less forested in a general view; these elevations graãuálly decrease to the South until the levei of the sea to Atlantic littoral by the eastern border, and to Rio Grande do Sul savanah, which extends to Uruguay and Argentina. The biota is transitional from the highland prairies and forests of the plateau to lowland prairies of the pampas. Three faunistic Provinces are included: Guarani, Pampean, and Tupi. The most conspicuous dispersion is shown by the taxa proceeding from the plateau to savanah (Dispersion Centre Guarani); the pampean species occur in low percentage (Dispersion Centre Uruguay), and an inappreciable account of Tupi fauna (Dispersion Centre of «Serra do Mar»). The new records are: presence of Chironius pyrrhopogon, Hydrodynastes gigas, Bothrops neuwiedi para-naensis, Micrurus corallinus; intergradation zone of Guarani and Pampean geographic roces; and new taxa of snakes, which will be described brieflly. The systematic composition presents: Chelonia, 4 (3 Chelidae, 1 Testudinidae); Sauria, 10 (1 Gekkonidae, 2 Iguanidae, 1 Anguidae, 3 Teiidae, 3 Amphisbaenidae); Serpentes, 45 (35 Colubridae, 4 Elapidae, 6 Viperidae); Crocodylia (1 Crocodylidae).