RESUMO

As clostridioses são infecções comuns em rebanhos bovinos, causadas por microrganismos do gênero Clostridium e que afetam principalmente animais mais jovens. O objetivo deste estudo é relatar a evolução clínica e tratamento de um bovino acometido com carbúnculo sintomático. A paciente não apresentava histórico vacinal para clostridiose, e pertencia a um lote de animais em que já haviam ocorrido três mortes súbitas em curto período de tempo. Na avaliação física do animal em decúbito esternal, foram constatados sinais clínicos típicos de carbúnculo sintomático, edema e crepitação em membro pélvico e região escapular, além de claudicação quando colocado em estação. Também foi observado edema na região da cabeça, porém este sinal clínico não é frequentemente relatado em literatura científica. Mesmo com prognóstico desfavorável devido à manifestação grave da doença e grande parte das pesquisas mostrarem taxa de letalidade de quase 100%, optou-se pela tentativa de realizar as medidas terapêuticas necessárias. Foi realizado tratamento suporte e administração de fármacos, destacando-se a antibioticoterapia com penicilina. Além disso, também foi conduzido o procedimento cirúrgico por meio de confecção de incisões na pele e no subcutâneo do membro afetado (método ainda não descrito na literatura científica) com objetivo de reduzir a proliferação do Clostridium. Após 32 dias de tratamento, o animal obteve a cura clínica completa. As medidas terapêuticas foram suficientes para recuperar da saúde da paciente.

Clostridial diseases are common infections in cattle herds, caused by microorganisms of the genus Clostridium that mainly affect younger animals. This study aims to report the clinical evolution and treatment of a bovine affected with symptomatic blackleg. The patient had no vaccination history for clostridial disease and belonged to a group of animals in which three sudden deaths had already occurred in a short time. In the physical evaluation of the animal in sternal recumbency, typical clinical signs of blackleg, edema and crackling in the pelvic limb and scapular region and lameness when placed in the station were determined. Edema was also observed in the head region, but this clinical sign is not frequently reported in the scientific literature. Even with an unfavorable prognosis due to the severe manifestation of the disease and a large part of the studies showing a lethality rate of almost 100%, it was decided to try to carry out the necessary therapeutic methods. Support treatment and drug administration were performed, especially antibiotic therapy with penicillin. In addition, a surgical procedure was carried out by making incisions in the skin and subcutaneous tissue of the affected limb (a method not yet described in the scientific literature) to reduce the proliferation of Clostridium. After thirty-two days of treatment, the animal got a complete clinical cure. Therapeutic measures were sufficient to recover the patient's health.

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Beta toxins (CPB) produced by Clostridium perfringens type B and C cause various diseases in animals, and the use of toxoids is an important prophylactic measure against such diseases. Promising recombinant toxoids have been developed recently. However, both soluble and insoluble proteins expressed in Escherichia coli can interfere with the production and immunogenicity of these antigens. In this context, bioinformatics tools have been used to design new versions of the beta toxin, and levels of expression and solubility were evaluated in different strains of E. coli. The immunogenicity in sheep was assessed using the molecule with the greatest potential that was selected on analyzing these results. In silico analyzes, greater mRNA stability (-169.70 kcal/mol), solubility (-0.755), and better tertiary structure (-0.12) were shown by rCPB-C. None of the strains of E. coli expressed rFH8-CPB, but a high level of expression and solubility was shown by rCPB-C. Higher levels of total and neutralizing anti-CPB antibodies were observed in sheep inoculated with bacterins containing rCPB-C. Thus, this study suggests that due to higher productivity of rCPB-C in E. coli and immunogenicity, it is considered as the most promising molecule for the production of a recombinant vaccine against diseases caused by the beta toxin produced by C. perfringens type B and C.

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INTRODUCTION: There is consensus regarding the importance of blackleg vaccination as a preventive measure, and proper immunization protocols are available. However, few studies have evaluated the effectiveness of vaccine protection against Clostridium chauvoei and the treatment of the disease in calves exhibiting early or advanced clinical courses. This study describes twelve blackleg cases in unvaccinated calves and in calves that received a single dose of the vaccine. It also reports the recovery of some calves after antibiotic therapy. METHODOLOGY: Two necropsies of cattle dead from blackleg were performed. Fragments of skeletal muscle from these two cattle were immersed in paraffin for multiplex polymerase chain reaction (PCR) analysis. RESULTS: Twelve calves up to nine months of age developed signs of blackleg and eight died. Ten of those 9-month-old calves had received only the first dose of a blackleg vaccine at 4 months of age, but no booster. The last two affected calves belonged to a herd that had never been vaccinated. Four out of five calves treated with penicillin for 6-7 days recovered from the disease. The diagnosis of blackleg was based on necropsy, histopathological findings and detection of C. chauvoei in skeletal muscle samples of two necropsied calves using PCR. CONCLUSIONS: The occurrence of cases only in calves that did not receive a booster dose or were not vaccinated indicated that the vaccine used was effective when performed as recommended by the manufacturer. However, neglecting the booster resulted in casualties due to blackleg.

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