Characterization of anti-crotalic antibodies.

Crotalus durissus terrificus, C. d. collilineatus, C. d. cascavella and C. d. marajoensis are responsible minor but severe snake bites in Brazil. The venoms of these snakes share the presence of crotoxin, a neurotoxin comprising of two associated components, crotapotin and phospholipase A2 (PLA2). Treatment of the victims with specific antiserum is the unique effective therapeutic measure. The ability of anti-Crotalus antisera produced by the routine using crude venom to immunize horses or purified crotoxin and PLA2 as individual immunogens was compared. Antisera obtained from horses immunized with C. durissus terrificus crude venom were able to recognize and neutralize not only the toxins presents in C. durissus terrificus, but also the ones present in the venoms from C. d. collilineatus, C. d. cascavella and C. d. marajoensis. Antisera from horses immunized with individual crotoxin or PLA2, although in lesser titers, were also able of recognizing the toxins in all four Crotalus species and neutralize the lethality of the C. d. terrificus venom.

The improvement of the therapeutic anti-Lachesis muta serum production in horses.

The main features associated with pit viper envenomations include the intense local lesions such as oedema, necrosis, acute renal failure and other effects. The severity of these reactions to snakebite depends on the degree of envenomation. Lachesis muta venom (LMV) has weak lethal activity, but due to the large amount often inoculated, the effects are extremely severe and demand anti-venom with a high neutralizing capacity. LMV had the lowest neutralizing antibody induction capacity in horses when compared with that of other venoms. For example, Bothrops anti-venom serum neutralizes 180 times the equivalent LD(50) to Bothrops venom; Crotalus anti-venom neutralizes 250 LD(50) of this venom, while Lachesis anti-venom neutralizes only five LD(50) of the Lachesis toxins. To examine the reasons for this low antibody induction, the H(GP) mouse line, genetically selected for high antibody production received, at different times during immunization with sheep erythrocytes (SE), whole LMV and isolated venom fractions I-VI eluted by gel-filtration chromatography on Superdex75. The specific antibody responsiveness showed a partial, but significant suppression of the anti-SE antibody responses during the kinetics of the primary and even the secondary immunizations, after 50-100 microg of fractions IV and V administration 72-48 h before the first antigen injections. Fraction IV was then applied in a Superose 12 column and three samples were obtained. The peak IVA containing a component of Mr 27 kDa was liable with the immunosuppressive effect as made evident by its effect on the H mice anti-SE responses. Horses receiving the LMV exempt of fractions IV and V produce highly significant anti-Lachesis sera with a 45 LD(50) neutralizing activity, providing, for the first time, an efficient specific therapeutic heterologous serum for human use.

Neutralization of crotaline snake venoms from Central and South America by antivenoms produced in Brazil and Costa Rica.

A study was performed on the ability of antivenoms, produced in Brazil and Costa Rica, to neutralize lethal, hemorrhagic and coagulant activities of the venoms of 16 species of Central and South American snakes of the subfamily Crotalinae. Neutralization of lethality was studied by two different methods routinely used in the quality control of antivenoms at Instituto Butantan (IB) and Instituto Clodomiro Picado (ICP). Both antivenoms neutralized the majority of the venoms studied, but the values of effective doses 50% (ED(50)) differed markedly depending on the method used. In general, higher potencies were obtained with the method of ICP, where a challenge dose corresponding to 4 LD(50)s is used, than with the method of IB, where a challenge dose of 5 LD(50)s is employed. All venoms induced hemorrhagic activity in the mouse skin test, which was effectively neutralized by the two antivenoms. All venoms, except those of Porthidium nasutum and Bothriechis lateralis, induced coagulation of human plasma in vitro and both antivenoms were effective in the neutralization of this activity. In conclusion, our results provide evidence of an extensive cross reactivity between these antivenoms and Central and South American crotaline snake venoms.

Production of an effective anti-Bothrops-tetanus mixed hyperimmune serum of equine origin

The present investigation reveals the possibility of simultaneous immunization of horses with Bothrops or Crotalus snake venoms and Tetanus antigens for the production of anti-Bothrops-Tetanus or anti-Crotalus-Tetanus mixed serum, with high titers of the respective specific antibodies. Bothrops antivenoms with an average neutralizing titer of 4.16 mg venom/ml were obtained from plasma of horses with titers lower than 0.5 mg venom/ml when Tetanus antigens were not used. This suggests the existence of a synergism between Bothrops venoms and Tetanus antigens in the stimulation of the antibody response. The pooled plasma of the animal had a neutralizing titer of 21.0 mg/ml reference Bothrops venoms and 3,300 IU/ml to Tetanus antigens after purification by enzymatic digestion and ammonium sulphate precipitation. These experiments lead us to conclude that Bothrops envenomation therapy can be successfully performed using Anti-Bothrops-Tetanus serum also serving as Tetanus prophylaxis. anti-Crotalus-Tetanus serum can also be produced, although it is not of medical interest as Crotalus envenomation rarely results in local necrotizing lesions.

Effect of beta-propiolactone treatment on the complement activation mediated by equine antisera.

Reduction of complement activation through an alteration of the Fc fragment of immunoglobulins by beta-propiolactone treatment was carried out in equine antisera raised against rabies virus, Bothrops venoms and diphtherial toxin. Results were evaluated by means of an anaphylactic test performed on guinea-pigs, and compared to the ones obtained with the same sera purified by saline precipitation (ammonium sulfate), followed or not by enzymatic digestion with pepsin. Protein purity levels for antibothropic serum were 184.5 mg/g and 488.5 mg/g in beta-propiolactone treated and pepsin-digested sera, respectively. The recovery of specific activity was 100% and 62.5% when using antibothropic serum treated by beta-propiolactone and pepsin digestion, respectively. The antidiphtherial and anti-rabies sera treated with beta-propiolactone and pepsin presented protein purity levels of 5,698 and 7,179 Lf/g, 16,233 and 6,784 IU/g, respectively. The recovery of specific activity for these antisera were 88.8%, 77.7%, 100% and 36.5%, respectively. beta-propiolactone treatment induced a reduction in complement activation, tested "in vivo", without significant loss of biological activity. This treatment can be used in the preparation of heterologous immunoglobulins for human use.

Antigenic cross-reactivity among components of Brazilian Elapidae snake venoms.

Snake venoms from M. corallinus (LD50 = 7.1 +/- 0.83 micrograms), M. frontalis (LD50 = 19.3 +/- 3.13 micrograms), M. ibiboboca (LD50 = 19.8 +/- 2.07 micrograms) and M. spiixi (LD50 = 6.7 +/- 1.25 micrograms) (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 antisera 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 bands 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.

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

Producao da vacina anti-rabica veterinaria em suspensao de celulas BHK. / Veterinary antirabic vaccine production in BHK cells suspension

Em tanque de 150 litros de capacidade, contendo 100 litros de celulas BHK-21 cultivadas em suspensao, estas foram inoculadas com a amostra PV de virus fixo da raiva, para producao de vacina. Uma concentracao relativamente elevada de virus foi obtida apos 96 a 120 horas de cultivo, que permitiu a preparacao de vacina para imunizacao de caes e bovinos contra a raiva.Os testes laboratoriais de potencia pelos metodos do NIH, Habel e Koprowski foram plenamente satisfatorios. A vacina preparada para a imunizacao de bovinos, adicionada de hidroxido de aluminio, protegeu os 10 animais vacinados contra o desafio pela inoculacao de 4 x 10/8 DL50 (camundongo) e virus rabico isolado de morcego. Sao ainda apresentadas observacoes sobre a evolucao dos cultivos celulares e dinamica de replicacao viral nas suspensoes celulares usadas. Algumas das experiencias realizadas sugerem a possibilidade de preparacao de uma vacina nao inativada com a amostra PV

Possivel interferencia da antitoxina tetanica pre-existente, na vacinacao antitetanica. / Possible interference of preexisting tetanus antitoxin, in antitetanus vaccination

Estudou-se qual a possivel interferencia no desenvolvimento da imunidade antitetanica ativa em cobaias e camundongos, filhos de femeas vacinadas contra o tetano em diferentes epocas durante o periodo da prenhez. Verificou-se que a vacinacao das femeas, em gestacao nao interferiu, negativamente, no desenvolvimento da imunidade ativa dos animais filhos quando submetidos a vacinacao ao redor de 60 dias apos o nascimento. A presenca de baixos niveis de anticorpos circulantes, recebidos congenitamente, parece ter, em determinadas condicoes, estimulado a resposta imunitaria quando, posteriormente, os animais filhos foram vacinados contra o tetano. Sugere-se que o complexo antigeno-anticorpo formado seja capaz de melhorar a resposta imunitaria induzida pelo toxoide

Vacinacao anti-rabica experimental.Possivel influencia da replicacao do virus Flury HEP modificado, no sistema nervoso central, sobre a atividade cerebro-neutralizante. / Experimental anti-rabies vaccination. Possible influence of Flury HEP modified virus replication in the central nervous system on the brain-tissue neutralization activity

Instalacao e replicacao do virus vacinante Flury HEP no tecido cerebral de animais inoculados. Inoculacoes intracerebrais (IC) e intramusculares (IM) das vacinas Flury HEP virus modificado, Flury HEP virus inativado e tipo Fuenzalida e Palacios, em lotes de 20 camundongos, comprovaram inducao de maior atividade cerebro-neutralizante pelo primeiro tipo de vacina.Demonstraram tambem ser viavel a replicacao viral no sistema nervoso central (SNC), aparentemente sem danos ao animal. As inoculacoes via IC e via IM induziram ao aparecimento de corpusculos fluorescentes no SNC, em maior intensidade ao redor de 8o.dia