Loxosceles venoms contains several protein toxins including alkaline phosphatases, hyaluronidases, metalloproteases, sphingomyelinases, and insecticidal peptides ( da Silva et al., 2004). Among venom toxins, sphingomyelinases, also called dermonecrotic toxins, are the major toxic components and play an essential role on the pathogenesis of loxoscelism ( Tambourgi et al., 2010). By using molecular biology tools, dermonecrotic toxins have been identified, the crystal structure determined, the cDNAs encoding toxins isolated, characterized and the recombinant proteins expressed, providing new insight for this PLX4032 group of toxins ( Kalapothakis et al., 2002; Murakami et al., 2006; de Santi Ferrara et al., 2009;

Catalán et al., 2011; da Silveira et al., 2006). Immunization strategies using crude Loxosceles venoms, recombinant toxins or synthetic epitopes derived from these toxins support the notion of using these immunogens as therapeutics

via anti-sera development or vaccine strategy ( Olvera et al., 2006; de Almeida et al., 2008; Dias-Lopes et al., 2010; de Moura et al., 2011). Antivenoms prepared from horse sera immunized with crude Loxosceles venoms are an important tool for treatment of human envenomation by spider and its use recommended by the Public Health Organizations ( Pauli et al., 2009). In view of the absence of information about the properties of PLlv toxins, the main goal of this work is to report some biochemical, immunological and toxic properties of this venom. In

DNA Damage inhibitor this paper, the sphingomyelinase, dermonecrotic, hemorrhagic, edematogenic and lethal activities of crude venom were investigated. This manuscript also describes the separation of soluble venoms proteins by 2-D SDS-PAGE, highlighting the differences between PLlv and BLlv protein pattern. In addition, this study shows the capacity of rabbit polyclonal anti-PLlv, anti-BLlv and, also horse anti-loxoscelic sera to neutralize Brazilian and Peruvian Loxosceles laeta venoms toxic effects. Adult male Swiss mice (weighing 18–22 g) were maintained at the Centro de Bioterismo of the Instituto de Ciências Biológicas of the Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil. Lonafarnib All animals received water and food ad libitum. The experimental protocols conformed to the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No. 85-23, revised 1996) (A5452-01). Eight- to nine-week-old New Zealand rabbits were used to produce the sera anti-PLlv and anti-BLlv. Animals were maintained and handled as described above. L. laeta (Peru) mature spiders were collected in the region of Cañete (Lima, Peru) and maintained in the herpetarium of the Centro Nacional de Producción de Biologicos of Instituto Nacional de Salud (INS), in Lima, Peru. Spiders were maintained in plastic boxes with water ad libitum and were fed weekly with cockroaches.