Resposta humoral de bovinos vacinados contra as toxinas botulínicas tipos C e D em diferentes faixas etárias

Abstract

RESUMOFoi verificada pelo teste de ELISA indireto a resposta humoral contra os toxoides botulínicos C e D em bovinos de diferentes idades. O estudo envolveu 90 animais, que foram divididos em três grupos (n = 30), de acordo com a sua faixa etária; inferior a 2 anos de idade (G1), entre 2 e 5 anos (G2) e superior a 5 anos (G3). Os grupos experimentais foram vacinados com duas doses de vacina antibotulínica bivalente (C e D) comercial, nos dias 0 e 42 após a primo-vacinação (booster). Na avaliação, quando realizada 30 dias após o booster, os animais do G3 apresentaram maior produção de anticorpos (p < 0,05) em relação aos demais grupos. Entre o G1 e G2 não houve diferença significativa na resposta humoral contra a toxina C, no entanto, contra a toxina D, os animais do G1 apresentaram maior produção de anticorpos. Todos os grupos produziram uma resposta significativa de anticorpos contra as toxinas botulínicas após a 2ª dose da vacina bivalente comercial, principalmente contra o tipo D.PALAVRAS-CHAVE: Anticorpos, botulismo, Clostridium botulinum C e D, vacinação. ABSTRACT HUMORAL RESPONSE OF VACCINATED CATTLE AGAINST TOXINS OF CLOSTRIDIUM BOTULINUM TYPES C AND D AT DIFFERENT AGES.Cattle humoral response against type C and D botulinum toxoids (indirect ELISA) was verified in animals of different ages. The animals (n = 90) were divided in three groups (n = 30): group one (G1): less than two years old; group two (G2): from 2 to 5 years old; group three (G3): more than 5 years old. The groups were vaccinated with two doses [0 and 42 days after primary vaccination (booster)] of bivalent (C and D) antibotulinum vaccine. Group three had higher antibody production (p ≤ 0.05) compared to the other groups, 30 days after the booster. There was no difference (G1 and G2; p ≥ 0.05) in the humoral response against C toxin, however, against D toxin, group one had higher antibody production. It was possible to conclude that after two doses of the commercial bivalent vaccine all groups produced a significant antibody response against botulinum toxins, especially against D type.

Economic impact of an outbreak of botulism in a cattle feedlot

“…So, even the polyvalent vaccine, with a cost of 36.74% more than the vaccine that would protect the herd only against botulism, is economically viable, considering the losses caused by the deaths of animals in the feedlot studied in this work, and the risk of other clostridioses diseases occurring. It is important to note that although the vaccination of cattle against botulism, both in intensive systems such as in extensive systems as a recommended prophylactic sanitary measure (Anniballi et al 2013, Cursi et al 2013 and also as an economically viable option with regards to mitigating the economic losses that botulism generated in the present case, under the conditions in which the outbreak of this study occurred, this procedure would not be recommended after the appearance of clinical cases. The proper explanation for this is that, firstly, the exposed cattle are already predisposed to the action of the botulinum neurotoxin, and the vaccine only has a preventive effect and not a therapeutic effect in animals already intoxicated (Steinman et al 2006).…”

“…When analyzing sanitary indicators, such as the absence of vaccination in conjunction with inadequate feed conservation, the risks for botulism in the herd increase considerably and consequently cause significant economic losses (Barros et al 2006, Cursi et al 2013. These two conditions occurred in the outbreak studied.…”

“…When vaccination of the herd with bivalent toxoids C and D is carried out in conjunction with a reduction in the exposure of the bovine to botulinum neurotoxin, then the rate of protection against the disease may reach 96% (Cursi et al 2013). For this, we recommend the protocol of vaccination with two doses, the primovaccination followed by booster vaccination between four to six weeks (Gaspar et al 2015).…”

“…The proper explanation for this is that, firstly, the exposed cattle are already predisposed to the action of the botulinum neurotoxin, and the vaccine only has a preventive effect and not a therapeutic effect in animals already intoxicated (Steinman et al 2006). Another factor is that the period required for the vaccine to stimulate an effective immune response involving the formation of antibodies against botulism is 30 days after primovaccination, on the second dose application (Riet-Correa 2007, Cursi et al 2013, and in the case evaluated in this study, the outbreaks occurred 70 days after the cattle entered in the feedlot. With that period, the establishment of immunity would coincide with the date of the outgoing of the animals for slaughter, thus making vaccination as a strategic procedure not feasible, in the specific case in the evaluated outbreak.…”

Causes of death in feedlot beef cattle and their control: a brief review

“…In feedlot beef cattle, conditions such as botulism (Maboni et al 2010, Soares et al 2018, Guizelini et al 2019, Le Maréchal et al 2019 occasionally cause economic losses in feedlot beef cattle operations. The study of an outbreak of botulism in the Midwest region with morbidity and mortality of 0.4% and a financial loss of more than US $ 13,000.00 is described (Curci et al 2013). In another outbreak in the same region (Guizelini et al 2019), a total of 1090 out of 1700 feedlot steers died due to the ingestion of corn silage contaminated with Clostridium botulinum neurotoxin type C (Fig.5).…”