Antigenic cross-reactivity among components of Brazilian Elapidae snake venoms

Snake venoms from M. corallinus (LD5=7.1 + or - 0.83 µg), M.frontalis (LD50=19.3 + or - 3.13 µg), M. ibiboboca (LD50=19.8 + or - 2.07 µg) and M. spiixi (LD50=6.7 + or - 1.25 µg) (family Elapidae, genus Micrurus) injected into horses alone or in combination (M. corallinus with M. frontalis) elicit antibody production, as indicated in vivo by neutralization of venom lethality and in vitro by enzyme-linked immunosorbent assay (ELISA), immunoelectrophoresis (IE) and Western blotting (WB). Venom lethality was efficiently neutralized by the antisera, with the monovalent antivenoms being more efficient than the bivalent antivenom. Antibodies against venom components were detected by all artisera at different titers by ELISA. Upon IE, antisera against M. spiixi and M. frontalis venoms cross-reacted with the four types of venoms studied and recognized several molecular components, the precipitin lines obtained had distinct intensities and electrophoretic motilities, whereas the antivenom against M. corallinus only recognized components of its venom but not of the others. All antivenoms cross-reacted with all the elapid venoms in WB revealing several blands with distinct MWs in M. corallinus and M. spiixi venoms, two very sharp and separate bands in M. corallinus venom and a very sharp band of high MW together with several other smaller and faint bands in M. frontalis venom. The data indicate that snake venoms of the genus Micrurus are good immunogens that contain many cross-reactive molecules, and that their toxic components are neutralized more effectively by monovalent rather than by bivalent antivenom

Evasion of Trypanosoma cruzi from complement lysis

This review outlines: a) the main biochemical and biological properties of the complement system (C) componentes; b) the manner through which they interact in the two distinct routes of C activation, the classical and the alternative pathways, to generate the enzymes C3 and C5 convertases responsible for release of the peptides C4a, C3a and C5a endowed with the properties of mediating the early events of the inflammatory process or the potentially cytolytic complex C5b-C9; c) the main features of control of these activation processes; d) the identification of cell surface components present in the trypomastigote forms of Trypanosoma cruzi possibly involved in the mechanisms developed by this parasite to evade C lysis; e) the inactivation or removal of these cell surface components by enzymatic (trypsin or papin), chemical (periodate) or physical (heating at 45-C) treatments; f) isolation of these components by chromatographic methods; and, g) demonstration that some of these cell surace components interfere with C3 convertase formation or action in a manner similar to the decay accelerating factor (DAF)

Estudo imunobiológico de estoques de Trypanosoma cruzi isolados de pacientes na fase aguda da doença de Chagas

Estoques de tripanossomas isolados de pacientes na fase aguda da doença de Chagas foram injetados em grupos de camundongos albinos não isogênicos nas doses de 10³, 10(4) e 10(5) parasitas/camundongos. O curso da infecção foi seguido por três meses. A pctrasitemia foi em geral baixa, com picos recorrentes, na maioria das vezes os animais evoluiam para cronicidade. Somente um estoque induziu alto índice de mortalidade. Os parasitas e as lesões apesar de detectadas no pico da parasitemia e restritos ao coração estavam ausentes aos três meses. Nesta época os perfis de Igs apresentaram diferenças marcantes. Grupos de animais que foram inoculados com estes estoques foram desafiados com doses letais da cepa Y ou CL. Em alguns casos obteve-se uma parasitemia, mas patente.

Ten stocks of trypanosomes isolated from patients at the acute phase of Chagas'disease were injected into groups of outbred normal mice at the doses of 10³, 10(4) and 10s5 parasites/mouse and the course of the infections followed up for 3 months. The parasitemia was usually low, with recurrent peaks, the animals evolving to chronicity, only one of them inducing high ratio of mortality. Pattems of parasitemia and mortality were essentially different for each stock studied; only one stock did show similar pattems to well known strains (Yand CL) commonly used in experimental work. Parasites and lesions, although detected at the peak of parasitemia and restricted to heart were absent after three months. At this period the Igs profiles showed striking differences with respect to their distribution. Groups of mice that had been inoculated with one of the stocks were challenged with the Y or CL strains. In some instances low parasitemias although patent were seen after the infecting dose.