Immunoprotection against lethal effects of Crotalus durissus snake venom elicited by synthetic epitopes trapped in liposomes.

Snakebites caused by Crotalus genus are the second most frequent in Brazil. Crotoxin is a beta-neurotoxin responsible for the main envenomation effects of Crotalus biting, while crotamine immobilizes the animal hind limbs, contributing to prey immobilization and to envenoming symptoms. As crotoxin and crotamine represent about 90% of Crotalus venom dry weight, these toxins are of great importance for antivenom therapy. In this sense, knowledge regarding the antigenicity/immunogenicity at the molecular level of these toxins can provide valuable information for the improvement of specific antivenoms. Therefore, the aims of this study are the identification of the B-cell epitopes from crotoxin and crotamine; and the characterization of the neutralizing potency of antibodies directed against the corresponding synthetic epitopes defined in the current study. Linear B-cell epitopes were identified using the Spot Synthesis technique probed with specific anti-C. d. terrificus venom horse IgG. One epitope of crotamine (F12PKEKICLPPSSDFGKMDCRW32) and three of crotoxin (L10LVGVEGHLLQFNKMIKFETR30; Y43CGWGGRGRPKDATDRCCFVH63 and T118YKYGYMFYPDSRCRGPSETC138) were identified. After synthesis in their soluble form, the peptides mixture correspondent to the mapped epitopes was entrapped in liposomes and used as immunogens for antibody production in rabbits. Anti-synthetic peptide antibodies were able to protect mice from the lethal activity of C. d. terrificus venom.

Exposure to fluctuating temperatures leads to reduced immunity and to stress response in rattlesnakes.

Ectothermic organisms often experience considerable variation in their body temperature throughout the circadian cycle. However, studies focusing on the measurement of physiological traits are usually performed under constant temperature regimes. This mismatch between thermal exposure in the field and experimental conditions could act as a stressor agent, as physiological functions are strongly influenced by temperature. Herein, we asked the question whether constant thermal regimes would cause a stress response and impact the immunity of the South American rattlesnake (Crotalus durissus) when compared with a fluctuating thermal regime. We addressed this question by determining heterophil:lymphocyte (H:L) ratio, plasma bacteria-killing ability (BKA) and corticosterone (CORT) levels in snakes kept under a constant temperature regime at 30°C, and under a fluctuating regime that oscillated between 25°C at night and 35°C during the day. The experiments had a mirrored design, in which half of the snakes were subjected to a fluctuating-to-constant treatment, while the other half was exposed to a constant-to-fluctuating treatment. The shift from constant to fluctuating thermal regime was accompanied by an increase in plasma CORT levels, indicating the activation of a stress response. Exposure to a fluctuating thermal regime at the onset of the experiments induced a decrease in the BKA of rattlesnakes. H:L ratio was not affected by treatments and, therefore, the shift between thermal regimes seems to have acted as a low-intensity stressor. Our results suggest that removal from temperatures close to the snake's preferred body temperature triggers a stress response in rattlesnakes.

Antibacterial properties of plasma from the prairie rattlesnake (Crotalus viridis).

The innate immune system functions to quickly respond to pathogens and is likely the primary line of defense for ectothermic vertebrates. Snake populations appear to be in widespread decline globally, but despite the threats from emerging pathogens, very little work has been conducted to characterize their basic immune function. We used a wide-ranging snake species, the Prairie Rattlesnake (Crotalus viridis), to measure effects of snake plasma on the growth of eight bacterial species. Additionally, we quantified bacterial killing ability and kinetics of the immune response. Our results show that Prairie Rattlesnakes have robust innate immune systems, and concentrations of 10% snake plasma inhibit growth of 6 of 8 bacteria tested. Undiluted snake plasma inhibited nearly all bacterial growth. The immune response was fairly rapid, inhibiting 73% of bacterial growth within 20 min of exposure. These results are encouraging for conservation of wild populations, as snakes appear to exhibit a strong innate immune response. However, further work needs to be directed toward the evaluation of immune system capabilities in individual populations of conservation concern, and against pathogens known to cause mortality in wild snakes.

When less means more: dehydration improves innate immunity in rattlesnakes.

Immune function can vary based on availability of resources, and most studies of such influences have focused on the co-investment of energy into immune and other physiological functions. When energy resources are limited, trade-offs exist, which can compromise immunity for other functions. As with energy, water limitation can also alter various physiological processes, yet water has received little consideration for its possible role in modulating immune functions. We examined the relationship between immunocompetence and hydration state using the western diamond-backed rattlesnake (Crotalus atrox). This species is known to undergo substantial seasonal fluctuations in water availability with extreme limitations during the hot-dry season. We collected blood samples from free-ranging C. atrox to compare osmolality and innate immune function (lysis, agglutination and bacterial growth inhibition) during the milder and relatively moister early spring season, the hot-dry season and the hot-wet season. To isolate effects of dehydration from other possible seasonal influences, we complemented this field study with a laboratory study in which we withheld food and water from individually housed adult C. atrox for up to 16 weeks. We collected blood samples from each snake as it dehydrated and collected a final sample after the snake was given water ad libitum at the end of the experiment. Our results demonstrate that C. atrox experience significant dehydration during the hot-dry season, and that, in general, innate immune function is highly correlated with osmolality, whether natural or artificially manipulated.

Proteomic, toxicological and immunogenic characterization of Mexican west-coast rattlesnake (Crotalus basiliscus) venom and its immunological relatedness with the venom of Central American rattlesnake (Crotalus simus).

The venom of the Mexican west-coast rattlesnake (Crotalus basiliscus) was characterized for its protein composition, toxicological profile and immunogenic properties. This venom is composed of 68% Zn2+-dependent metalloproteinases (SVMPs), 14% phospholipases A2 (PLA2s), 11% serine proteinases, 4% SVMPs-inhibitor tripeptides (SVMP-ITs), 2% bradykinin-potentiating peptides (BPPs), 0.6% cysteine-rich secretory proteins (CRISPs), and 0.2% l-amino acid oxidases (LAAOs). SVMPs present in the venom are responsible for azocasein hydrolysis and hemorrhagic activity, but their contribution to the lethal activity of the venom in mice is masked by the neurotoxic activity of PLA2s, which in addition are also responsible for myotoxic activity. Despite its relatively high content of serine proteinases, the venom of C. basiliscus did not exert in vitro coagulant or in vivo defibrinogenating activities. The ability of antivenoms raised against the venoms of C. basiliscus and C. simus (from Costa Rica) to neutralize homologous and heterologous venoms revealed antigenic similarities between toxins of both venoms. Preclinical evaluation of an antivenom produced by using the venom of C. basiliscus as immunogen demonstrated that it is able to neutralize not only the most relevant toxic activities of C. basiliscus venom, but also those exerted by Costa Rican C. simus venom, including coagulant and defibrinogenating activities. BIOLOGICAL SIGNIFICANCE: The Central American rattlesnake (Crotalus simus) is widely distributed from Mexico to west central Costa Rica, and induces an important number of envenomations in this region. On the other hand, the immunogenic mixture used by Laboratorios de Biológicos y Reactivos de Mexico S.A. (Birmex) to produce the snake antivenom more frequently used in Mexico does not include the venom of C. simus. This immunogenic mixture is composed by the venoms of the Fer-de-lance (Bothrops asper) and the Mexican west-coast rattlesnake (Crotalus basiliscus). We studied the protein composition, toxicological profile and immunogenic properties of the venom of C. basiliscus, and evaluated the ability of the Birmex antivenom to neutralize the venom of C. basiliscus and whether it cross-neutralizes the venom of C. simus from Costa Rica. Using proteomics analysis, in combination with in vitro and mouse tests, we determined that the venom of C. basiliscus is mainly composed by SVMPs, which confer proteolytic and hemorrhagic activities to the venom. Other major components of the venom of C. basiliscus are PLA2s, which are responsible for the myotoxic activity and are the main contributors to the lethal activity. Non-clotting SVSPs correspond to 11% of the venom. Minor components include SVMP-ITs, BPPs, CRISPs and LAAOs, which have not been associated with toxicity. The antibodies induced in horses by the venom of C. basiliscus are able to neutralize not only the most relevant toxic activities of the homologous venom, but also those exerted by Costa Rican C. simus venom, including coagulant and defibrinogenating activities. Our preclinical evaluation suggests that Birmex antivenom can be used to treat envenomations by Costa Rican adult C. simus snakebites, despite this venom not being included in the immunizing mixture.

The binding effectiveness of anti-r-disintegrin polyclonal antibodies against disintegrins and PII and PIII metalloproteases: An immunological survey of type A, B and A+B venoms from Mohave rattlesnakes.

Snake venoms are known to have different venom compositions and toxicity, but differences can also be found within populations of the same species contributing to the complexity of treatment of envenomated victims. One of the first well-documented intraspecies venom variations comes from the Mohave rattlesnake (Crotalus scutulatus scutulatus). Initially, three types of venoms were described; type A venom is the most toxic as a result of ~45% Mojave toxin in the venom composition, type B lacks the Mojave toxin but contains over 50% of snake venom metalloproteases (SVMPs). Also, type A+B venom contains a combination of Mojave toxin and SVMP. The use of an anti-disintegrin antibody in a simple Enzyme-Linked Immunosorbent Assay (ELISA) can be used to identify the difference between the venoms of the type A, B, and A+B Mohave rattlesnakes. This study implements the use of an anti-recombinant disintegrin polyclonal antibody (ARDPA) for the detection of disintegrins and ADAMs (a disintegrin and metalloproteases) in individual crude snake venoms of Mohave rattlesnakes (Crotalus scutulatus scutulatus) of varying geographical locations. After correlation with Western blots, coagulation activity and LD50 data, it was determined that the antibody allows for a quick and cost-efficient identification of venom types.

Effect of iron and carbon monoxide on fibrinogenase-like degradation of plasmatic coagulation by venoms of four Crotalus species.

Annually, thousands suffer poisonous snake bite, often from defibrinogenating species. Iron and carbon monoxide (CO) improve coagulation kinetics by modulation of fibrinogen as demonstrated in various Agkistrodon species and Crotalus atrox. Thus, we sought to determine whether pretreatment of plasma with iron and CO could attenuate venom-mediated catalysis of fibrinogen obtained from four common Crotalus species with known fibrinogenase activity. Human plasma was pretreated with ferric chloride (0-10 µmol/l) and CO-releasing molecule-2 (0-100 µmol/l) prior to exposure to venom from a Northern Pacific rattlesnake, Arizona black rattlesnake, prairie rattlesnake, or red diamond rattlesnake. The concentration of venom used decreased coagulation function of one or more kinetic parameters by at least 50% of normal values. Coagulation kinetics were determined with thrombelastography.Three snake venoms significantly degraded plasmatic coagulation kinetics, prolonging the onset to clot formation, diminishing velocity of clot growth and decreasing clot strength. However, red diamond rattlesnake venom exposure resulted in mixed coagulation kinetics, significantly decreasing the time to onset of coagulation without decreasing the velocity of clot growth. Iron and CO attenuated these coagulation kinetic changes in a species-specific manner. Further in vitro investigation of other fibrinogenolytic venoms is indicated to determine if iron and CO can attenuate venom compromised coagulation.

Anti-Leptospira spp. antibodies in Crotalus durissus collilineatus kept in captivity and its zoonotic relevance.

Leptospirosis is a worldwide spread zoonosis that can affect all groups of vertebrates, including reptiles. Because it has been little studied in snakes, this study focused on determining the occurrence of anti-Leptospira spp. antibodies in 64 Crotalus durissus collilineatus kept in captivity and on identifying the most common serovars in these animals, using the microscopic agglutination test. Of these, almost 90% were positive and there were reactions to the 22 serovars used in the study. The most common serovar in these snakes was Javanica, Andamana and Patoc. Most frequent titers were 25 and 50, although high titers (such as 1600) were also recorded, despite the absence of clinical symptoms. The possibility should be considered of captive snakes serving as a serious source of leptospiral infection in humans, which is why it is essential to study, prevent and control the disease in breeding centers and serpentariums.

Antibody responses to natural rattlesnake envenomation and a rattlesnake toxoid vaccine in horses.

Antivenom antibody titers following administration of rattlesnake venom for antivenom production in horses are well documented; however, antivenom antibody titers following natural rattlesnake envenomation in horses are not. Antibody titers produced in response to the commercially available rattlesnake venom vaccine are also not published. Our study objectives were to measure antivenom antibody titers in rattlesnake-bitten horses and compare them to titers in horses vaccinated with the rattlesnake venom vaccine. Additionally, titers were compared in pregnant versus nonpregnant horses to assess the affect of pregnancy on vaccine response and were measured pre- and postsuckle in foals of vaccinated mares to detect passive transfer of vaccine immunoglobulins. Blood samples were collected from 16 rattlesnake-bitten horses. Thirty-six horses (11 pregnant mares, 12 nonpregnant mares, 13 geldings) were vaccinated using a Crotalus atrox venom toxoid vaccine. Blood was collected before administering each vaccination and 30 days following the third vaccination. Blood was collected from foals of vaccinated mares pre- and postsuckle. All serum was assayed for anti-Crotalus atrox venom antibodies using an enzyme-linked immunosorbent assay (ELISA). Rattlesnake-bitten horses had higher (P = 0.001) titers than vaccinated horses. There was no significant difference between titers in vaccinated pregnant versus nonpregnant horses. One mare had a positive titer at foaling, and the foals had positive postsuckle titers. Antivenom antibody titer development was variable following natural envenomation and vaccination, and vaccine-induced titers were lower than natural envenomation titers. Further studies are required to determine if natural or vaccine antivenom antibody titers reduce the effects of envenomation.

Avaliação da resposta inflamatória hematológica em cascavéis (Crotalus durissus Linnaeus, 1758) inoculadas com BCG / Assessment of blood inflammatory response in BCG stimulated rattlesnakes (Crotalus durissus Linnaeus, 1758)

A criação de serpentes peçonhentas em cativeiro para produção de soros antipeçonhas possui crescente importância para a saúde pública devido ao aumento do número de notificações de acidentes ofídicos a cada ano no Brasil. Iniciado no século XX, ainda hoje essa atividade apresenta alguns desafios como a instalação de doenças no plantel. O hemograma é um exame de triagem clínica que auxilia no diagnóstico de diversas moléstias que acometem diferentes espécies de animais, no entanto ainda pouco estudado em serpentes. A caracterização das alterações hematológicas em cascavéis inoculadas experimentalmente com BCG pode servir de base na utilização deste exame no auxílio ao diagnóstico de infecções bacterianas na espécie. Dessa forma, foram realizados exames hematológicos em 10 serpentes da espécie Crotalus durissus pertencentes ao plantel da Divisão de Herpetologia do Instituto Vital Brazil. Os animais foram divididos em dois grupos (Grupos 1 e 2), homogêneos entre si em relação ao peso e proporção sexual. Os dois grupos foram inoculados com BCG e submetidos à coleta de sangue antes da inoculação e em três momentos pós-inoculação (3º, 5º, e 7º dias para o Grupo 1 e 11º, 17º e 21º dias para o Grupo 2). O hemograma foi realizado por método semidireto pela utilização de líquido de Natt e Herrick e as lâminas foram coradas pelo Giemsa. Observou-se anemia discreta, com redução dos valores de concentração de hemoglobina corpuscular média e da hemoglobina globular média no Grupo 1 que foi relacionada à doença inflamatória. A trombocitopenia observada no Grupo 2 sugeriu a atuação deste tipo celular em processos inflamatórios. Um único animal do Grupo 1 apresentou granulocitose e alguns animais apresentaram discreta azurofilia. Observaram-se alterações morfológicas nos leucócitos. Os granulócitos apresentaram granulações grosseiras e os azurófilos apresentaram aumento de tamanho e grandes vacúolos. De forma geral, a inoculação de BCG em cascavéis desencadeia ...

The high demand for anti-venom production in response to the increased number of cases of snakebite envenomation highlights the importance of raising and breeding venomous snakes in captivity. Knowledge of types of venoms and anti-venoms is of great interest to public health. The maintenance of venomous serpents in captivity started in the early twentieth century, but still nowadays it is a challenge to manage and prevent diseases in captive fauna. Hematology is commonly used for general health assessment and illness detection. However, data on serpent blood analysis are still scarce. Alterations in hematological parameters were experimentally induced in rattlesnakes by the inoculation of BCG. Based on this, hemograms can be used as a health auxiliary diagnosis method for bacterial diseases in this species. In this study, blood samples were taken from 10 healthy specimens of rattlesnakes (Crotalus durissus) born and bred in captivity in the Herpetological Division of Vital Brazil Institute. Animals were divided into two groups (group 1 and 2) with similar live weight and sex proportion, and were then inoculated subcutaneously with BCG (Bacillus Calmette-Guérin). Blood samples were taken before and after inoculation at three experimental times (days 3, 5 and 7 for group 1 and days 11, 17 and 21 for group 2). Hematological analysis was performed through semi-direct technique, blood samples were diluted in Natt and Herrick solution and smears were stained by Giemsa. Serpents from group 1 developed discrete anemia due to the inflammatory syndrome, and showed significant decrease of MCH and MCHC. Granulocytes were characterized by the presence of rough granules. The azurophils varied in shape and size and showed large amount of cytoplasmic vacuoles. The thrombocytopenia observed in group 2 suggests that these cells participate in the inflammatory process. A single individual from group 1 showed granulocytosis and a few animals showed a discrete ...

Immune response and neutralization capacity of antibodies produced in young sheep immunized with Crotalus durissus terrificus native or Cobalt-60 irradiated venom / esposta imune e capacidade de neutralização de anticorpos produzidos em ovinos jovens imunizados com veneno de Crotalus durissus terrificus nativo e irradiado com Cobalto 60

The ELISA technique was used to evaluate and compare young ovine humoral immune response during crotalic antiserum production. Animals were clinically evaluated throughout this process, and the neutralizing capacity of antisera raised against natural (NV) and Cobalt-60 irradiated (IrV) venoms of Crotalus durissus terrificus (C.d.t.) was verified by means of in vitro challenges. Three groups of six animals each were used: G1 received NV; G2 was inoculated with IrV; and G3 was used as control. Animals received six immunizations during 84 days at 14-day intervals. ELISA of antibody profile showed significant difference (p<5%) between experimental groups (G1

A técnica de Elisa foi utilizada para avaliar e comparar a resposta imune humoral de ovinos jovens para a produção de soro anticrotálico. Durante o processo de soroprodução, foi realizada a avaliação clínica dos animais. A capacidade de neutralização do soro produzido a partir de veneno de serpente Crotalus durissus terrificus, nativo (VN) e irradiado (VIr) com Cobalto–60 foi verificada por meio de desafios in vitro. Um grupo de seis animais recebeu veneno nativo, o segundo grupo recebeu veneno irradiado e o terceiro grupo foi o controle. Os animais receberam seis imunizações durante 84 dias com intervalo de14 dias. Houve diferença significativa (p<5%) no teste de ELISA do perfil de anticorpos produzidos pelos grupos experimentais (VN

Rabbit IgG antibodies against phospholipase A2 from Crotalus durissus terrificus neutralize the lethal activity of the venom.

Crotalus durissus terrificus (C.d.t.) (South American rattlesnake) venom possesses myotoxic and neurotoxic activities, both of which are also expressed by crotoxin, the principal toxin of this venom. Crotoxin contains a basic phospholipase A2 (PLA2) and a non toxic acidic protein, crotapotin. We have produced and investigated the ability of IgG antibodies raised in rabbits against PLA2 to neutralize the lethality of the whole venom. PLA2 was isolated by gel filtration chromatography (Sephadex G-75). Specific antibodies were obtained by subcutaneous and intramuscular inoculation of PLA2 (700 microg) with Freund adjuvant. Groups of six mice (20 + 2 g) were inoculated with 0.5 ml i.p. of C. d t. venom (4 microg) or a mixture of venom that had been preincubated with the desired volume of IgG antibodies. Mortality, recorded 24 and 48 h after inoculation, showed that IgG anti-PLA2 were more effective than anticrotalic serum in neutralizing the lethal activity. These results demonstrate that it could be possible to obtain an anti-venom made by specific antibodies with a high level of protection against the lethal component of C.d.t. venom, and/or the inclusion of these antibodies as a supplement in heterologous anti-venoms.

Rabbit IgG antibodies against Phospholipase A2 from Crotalus durissus terrificus neutralize the lethal activity of the venom

Crotalus durissus terrificus (C.d.t.) (South American rattlesnake) venom possesses myotoxic and neurotoxic activities, both of which are also expressed by crotoxin, the principal toxin of this venom. Crotoxin contains a basic phospholipase A2 (PLA2) and a non toxic acidic protein, crotapotin. We have produced and investigated the ability of IgG antibodies raised in rabbits against PLA2 to neutralize the lethality of the whole venom. PLA2 was isolated by gel filtration chromatography (Sephadex G-75). Specific antibodies were obtained by subcutaneous and intramuscular inoculation of PLA2 (700 µg) with Freund adjuvant. Groups of six mice (20 + 2 g) were inoculated with 0.5 ml i.p. of C. d. t. venom (4 µg) or a mixture of venom that had been preincubated with the desired volume of IgG antibodies. Mortality, recorded 24 and 48 h after inoculation, showed that IgG anti-PLA2 were more effective than anticrotalic serum in neutralizing the lethal activity. These results demonstrate that it could be possible to obtain an anti-venom made by specific antibodies with a high level of protection against the lethal component of C.d.t. venom, and/or the inclusion of these antibodies as a supplement in heterologous anti-venoms

El veneno de Crotalus durissus terrificus (C.d.t.) (Cascabel de Sud América) posee actividad miotóxica y neurotóxica, actividades que también exhibe el complejo crotoxina, principal componente tóxico de este veneno. El complejo crotoxina está constituido por una fosfolipasa A2 básica (PLA2) y una proteína acídica no tóxica, el crotapotín. En este trabajo se estudió la capacidad neutralizante de anticuerpos IgG anti-PLA2 sobre la letalidad inducida por el veneno entero. El antígeno PLA2, fue aislado por cromatografía de filtración en gel (Sephadex G-75). Se inocularon conejos machos por vía subcutánea e intramuscular, con 700 µg de PLA2 y adyuvante para la obtención de anticuerpos específicos. La capacidad neutralizante del antisuero se analizó en ratones por inoculación con diluciones de veneno entero preincubado con un volumen adecuado de anticuerpos IgG anti-PLA2. Se inocularon ratones controles con 0.5 ml i.p. de veneno (4 µg.ml-1). El número de muertes fue contabilizado a las 24 y 48 h posteriores a la inoculación, demostrándose que la capacidad neutralizante de los anticuerpos IgG anti-PLA2 fue superior a la obtenida con el antiveneno crotálico. Los resultados obtenidos demuestran la potencial aplicación de antivenenos constituidos por anticuerpos específicos contra PLA2, y/o la inclusión de estos anticuerpos como suplementos en antivenenos polivalentes

Rabbit IgG antibodies against Phospholipase A2 from Crotalus durissus terrificus neutralize the lethal activity of the venom

Crotalus durissus terrificus (C.d.t.) (South American rattlesnake) venom possesses myotoxic and neurotoxic activities, both of which are also expressed by crotoxin, the principal toxin of this venom. Crotoxin contains a basic phospholipase A2 (PLA2) and a non toxic acidic protein, crotapotin. We have produced and investigated the ability of IgG antibodies raised in rabbits against PLA2 to neutralize the lethality of the whole venom. PLA2 was isolated by gel filtration chromatography (Sephadex G-75). Specific antibodies were obtained by subcutaneous and intramuscular inoculation of PLA2 (700 Ag) with Freund adjuvant. Groups of six mice (20 + 2 g) were inoculated with 0.5 ml i.p. of C. d. t. venom (4 Ag) or a mixture of venom that had been preincubated with the desired volume of IgG antibodies. Mortality, recorded 24 and 48 h after inoculation, showed that IgG anti-PLA2 were more effective than anticrotalic serum in neutralizing the lethal activity. These results demonstrate that it could be possible to obtain an anti-venom made by specific antibodies with a high level of protection against the lethal component of C.d.t. venom, and/or the inclusion of these antibodies as a supplement in heterologous anti-venoms (AU)

El veneno de Crotalus durissus terrificus (C.d.t.) (Cascabel de Sud América) posee actividad miotóxica y neurotóxica, actividades que también exhibe el complejo crotoxina, principal componente tóxico de este veneno. El complejo crotoxina está constituido por una fosfolipasa A2 básica (PLA2) y una proteína acídica no tóxica, el crotapotín. En este trabajo se estudió la capacidad neutralizante de anticuerpos IgG anti-PLA2 sobre la letalidad inducida por el veneno entero. El antígeno PLA2, fue aislado por cromatografía de filtración en gel (Sephadex G-75). Se inocularon conejos machos por vía subcutánea e intramuscular, con 700 Ag de PLA2 y adyuvante para la obtención de anticuerpos específicos. La capacidad neutralizante del antisuero se analizó en ratones por inoculación con diluciones de veneno entero preincubado con un volumen adecuado de anticuerpos IgG anti-PLA2. Se inocularon ratones controles con 0.5 ml i.p. de veneno (4 Ag.ml-1). El número de muertes fue contabilizado a las 24 y 48 h posteriores a la inoculación, demostrándose que la capacidad neutralizante de los anticuerpos IgG anti-PLA2 fue superior a la obtenida con el antiveneno crotálico. Los resultados obtenidos demuestran la potencial aplicación de antivenenos constituidos por anticuerpos específicos contra PLA2, y/o la inclusión de estos anticuerpos como suplementos en antivenenos polivalentes (AU)

Rabbit IgG antibodies against Phospholipase A2 from Crotalus durissus terrificus neutralize the lethal activity of the venom

Crotalus durissus terrificus (C.d.t.) (South American rattlesnake) venom possesses myotoxic and neurotoxic activities, both of which are also expressed by crotoxin, the principal toxin of this venom. Crotoxin contains a basic phospholipase A2 (PLA2) and a non toxic acidic protein, crotapotin. We have produced and investigated the ability of IgG antibodies raised in rabbits against PLA2 to neutralize the lethality of the whole venom. PLA2 was isolated by gel filtration chromatography (Sephadex G-75). Specific antibodies were obtained by subcutaneous and intramuscular inoculation of PLA2 (700 Ag) with Freund adjuvant. Groups of six mice (20 + 2 g) were inoculated with 0.5 ml i.p. of C. d. t. venom (4 Ag) or a mixture of venom that had been preincubated with the desired volume of IgG antibodies. Mortality, recorded 24 and 48 h after inoculation, showed that IgG anti-PLA2 were more effective than anticrotalic serum in neutralizing the lethal activity. These results demonstrate that it could be possible to obtain an anti-venom made by specific antibodies with a high level of protection against the lethal component of C.d.t. venom, and/or the inclusion of these antibodies as a supplement in heterologous anti-venoms (AU)

El veneno de Crotalus durissus terrificus (C.d.t.) (Cascabel de Sud América) posee actividad miotóxica y neurotóxica, actividades que también exhibe el complejo crotoxina, principal componente tóxico de este veneno. El complejo crotoxina está constituido por una fosfolipasa A2 básica (PLA2) y una proteína acídica no tóxica, el crotapotín. En este trabajo se estudió la capacidad neutralizante de anticuerpos IgG anti-PLA2 sobre la letalidad inducida por el veneno entero. El antígeno PLA2, fue aislado por cromatografía de filtración en gel (Sephadex G-75). Se inocularon conejos machos por vía subcutánea e intramuscular, con 700 Ag de PLA2 y adyuvante para la obtención de anticuerpos específicos. La capacidad neutralizante del antisuero se analizó en ratones por inoculación con diluciones de veneno entero preincubado con un volumen adecuado de anticuerpos IgG anti-PLA2. Se inocularon ratones controles con 0.5 ml i.p. de veneno (4 Ag.ml-1). El número de muertes fue contabilizado a las 24 y 48 h posteriores a la inoculación, demostrándose que la capacidad neutralizante de los anticuerpos IgG anti-PLA2 fue superior a la obtenida con el antiveneno crotálico. Los resultados obtenidos demuestran la potencial aplicación de antivenenos constituidos por anticuerpos específicos contra PLA2, y/o la inclusión de estos anticuerpos como suplementos en antivenenos polivalentes (AU)

Polyclonal antibodies against a structure mimicking the covalent linkage unit between picornavirus RNA and VPg: an immunochemical study.

We propose that therapy of patients with anticancer drugs that poison DNA topoisomerases induces formation of covalent complexes of cellular RNAs and DNA topoisomerases. The appearance of these complexes can be detected with antibodies against a synthetic hapten mimicking the covalent linkage unit Tyr-pU(p) of picornavirus RNA and VPg. We synthesized hapten [N(Ac),CO(NH2)]Tyr-(5 P --> O)Up-O-(CH2)6NH2, conjugated it with BSA, and immunized rabbits with the antigen obtained. The raised polyclonal antibodies were purified by successive affinity chromatography on BSA-Sepharose and hapten-Sepharose columns. Target antibodies recognized hapten and encephalomyocarditis virus RNA-VPg complex specifically as found using the dot-immunogold method. We believe that these antibodies might be useful to study mechanism of picorna and similar virus RNA synthesis. The discovery and qualitative determination of the cellular RNA-DNA topoisomerases covalent complexes with these antibodies might be useful to monitor therapy efficacy by drugs "freezing" dead-end complexes of DNA topoisomerases and nucleic acids and to understand the mechanism of DNA topoisomerase poisoning in situ.

Determination of the neutralizing potency of horse antibothropic and anticrotalic antivenoms in blood samples collected on filter paper.

The correlation coefficients between in vivo neutralization of lethal toxicity (ED(50)) and levels of antibodies measured by enzyme-linked immunosorbent assay (ELISA) in blood samples collected on filter paper were investigated to test the potency of horse antibothropic and anticrotalic antivenoms. Sixteen horses were hyperimmunized with Bothrops venom (50% from B. jararaca and 12.5% each from B. alternatus, B. jararacussu, B. neuwiedii and B. moojeni) and 12 horses with Crotalus durissus terrificus venom. Crude venom of C. d. terrificus and the lethal fraction of B. jararaca venom were used as antigens to set up an indirect ELISA. The correlation coefficient between ED(50) and ELISA antibodies titers against C. d. terrificus and the lethal fraction of B. jararaca venom was r = 0.8 (P<0.001) and r = 0.78 (P<0.001), respectively.