Background: Mammomonogamus laryngeus is a hematophage nematode parasite that affects the respiratory tract of domestic mammals. The female and male are united in permanent copulation producing a distinctive "Y" form. So far, over 100 cases of human infection had been reported in the scientific literature. In Colombia in 2006 we reported the first case of human infection in the Quindio region, and the second report in bovine livestock with a high prevalence of 14.5% (Fig. 1). Methods: The protein profile of excretion/secretion (ES) of M. laryngeus was determined by SDS-PAGE electrophoresis and the characterization of the enzyme activity was evaluated with a zymogram using casein and gelatin dissolved in 20 mM sodium phosphate buffer at pH 7.4 and copolymerization with polyacrylamide 10% and to 0.8% bisacrylamide, 1.5 M Tris- HCl, pH 8.8. The protein concentration was determined by bicinchoninic acid assay (BCA). To evaluate the type of protease on the ES proteins, a zymogram assay was performed with and without specific protease inhibitors (leupeptin trifluoro acetate, EDTA, pepstatin A, 4-2 amino ethyl benzene sulfonyl fluoride Hydrochloric (AEBSF) and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK)) in 10% polyacrylamide gel and gelatin as substrate. To evaluate the effect of pH on the protein activity, the zymogram conditions were performed on pH from 4 to 11. Results: The products of ES from adult M. laryngeus have protease activity showing four bands with molecular masses of 94.4 kDa the most dominant and a diffuse series of bands of 122 kDa, 108 kDa and 72 kDa. The M. laryngeus ES shows a protease activity. For the specific family of proteases, a metallopretease activity was found corresponding to the inhibition of protease activity by EDTA but no under other inhibitor. The pH did not change the protease activity over the range tested. In the micrograph are observed Mammomonogamus laryngeus specimens in copula permanent. Conclusion: Our findings, suggest that maybe this ES proteins are involved in skin penetration process and migration through connective tissues in the host, therefore, it is mandatory to obtain more data about this parasite for the understanding of its infective process, and also look for ES homologies within the same family of nematodes for the searching of vaccine candidates and treatment strategies. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive