(2001). These results support the notion that toxins venoms share similar epitopes for dermonecrotic toxins ( Guilherme et al., 2001). In these assays, the neutralization of edema-inducing activity by PLlv afforded lower protection in immunized rabbits. Finally, we investigated the neutralization

of sphingomyelinase activity by commercial sera produced in Brazil and Peru. An in vitro neutralization assay was performed by pre-incubating PLlv and BLlv with different antivenom dilutions from CPPI and INS. The applied doses were 0.125 μg of PLlv and 0.250 μg of BLlv, once these values showed similar sphingomyelinase activity. Both antivenoms neutralized about MS-275 ic50 100% of both venoms activities in the dilution 1:100, and more than

80% in the dilution 1:500 ( Fig. 6A and B). On the other hand, with the 1:2500 dilution, only the CPPI serum partially neutralize both venom (30% for BLlv and 80% for PLlv, respectively). Previously, Olvera et al. (2006), had suggested designing a polyvalent antivenom and our results confirm that two different and interspecific SB203580 molecular weight commercial antivenoms are able to cross neutralize venoms from different species, supporting the idea of developing a “pan-American” or global loxoscelic antivenom ( Barbaro et al., 2005; Olvera et al., 2006). Fig. 7 In conclusion, our data suggest, based on the in vivo lethal effect and in vitro sphingomyelinase activity, that venom of Loxosceles laeta

from Peru is more toxic than BLlv and that antivenom antibodies raised in immunized rabbits or commercial sera produced in Brazil and in Peru are efficient in neutralizing the toxic activity of both venoms. We would like to express gratitude to Dr. Marcelo Santoro for his critical review of this manuscript. This research was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil – CAPES (Toxinologia no. 23038000825/2011-63), Fundação de Amparo a Pesquisa do Estado de Minas Gerais, Brazil much (FAPEMIG) and by funds of the INCTTOX Program of Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil (CNPq). The authors gratefully acknowledge the support and assistance of the Instituto Nacional de Salud, Peru. “
“Mygalomorphs (Arthropoda, Chelicerata, Arachnida, Araneae, Mygalomorphae) comprise tarantulas and trap-door spiders, which are distributed in 15 families, 300 genera and approximately 2500 species (Hedin and Bond, 2006). Distinctive characteristics of mygalomorphs include apparent external abdominal segmentation, longitudinal articulation of chelicera and the presence of laminar lungs (Barnes, 1993). Tarantulas are included in the family Theraphosidae, which is represented by around 900 species divided in 112 genera (Platnick, 2011).