M. R. A. Ferreira

Recombinant Alpha, Beta, and Epsilon Toxins of Clostridium perfringens: Production Strategies and Applications as Veterinary Vaccines.

Clostridium perfringens is a spore-forming, commensal, ubiquitous bacterium that is present in the gastrointestinal tract of healthy humans and animals. This bacterium produces up to 18 toxins. The species is classified into five toxinotypes (A–E) according to the toxins that the bacterium produces: alpha, beta, epsilon, or iota. Each of these toxinotypes is associated with myriad different, frequently fatal, illnesses that affect a range of farm animals and humans. Alpha, beta, and epsilon toxins are the main causes of disease. Vaccinations that generate neutralizing antibodies are the most common prophylactic measures that are currently in use. These vaccines consist of toxoids that are obtained from C. perfringens cultures. Recombinant vaccines offer several advantages over conventional toxoids, especially in terms of the production process. As such, they are steadily gaining ground as a promising vaccination solution. This review discusses the main strategies that are currently used to produce recombinant vaccines containing alpha, beta, and epsilon toxins of C. perfringens, as well as the potential application of these molecules as vaccines for mammalian livestock animals.

Escherichia coli enterohemorrágica O157: H7 em bovinos leiteiros saudáveis no Centro-Oeste do Brasil: ocorrência e caracterização molecular

Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 represents the major Shiga toxin-producing E. coli (STEC) strain related to large outbreaks and severe diseases such as hemorrhagic colitis (HC) and the potentially lethal hemolytic uremic syndrome (HUS). The aim of this study was to report the occurrence and molecular characterization of O157:H7 isolates obtained by rectal swab from 52 healthy dairy cattle belonging to 21 farms in Mid-West of Brazil. Detection of 16SrRNA, stx1, stx2, rfbO157, fliCh7, eae, ehxA, saa, cnf1, chuA, yjaA and TSPE4.C2 genes was performed by PCR. The isolates were further characterized by serotyping. Two hundred and sixty E. coli isolates were obtained, of which 126 were characterized as STEC. Two isolates from the same cow were identified as serotype O157:H7. Both isolates presented the stx2, eae, ehxA, saa and cnf1 virulence factor genes and the chuA gene in the phylogenetic classification (virulent group D), suggesting that they were clones. The prevalence of O157:H7 was found to be 1.92% (1/52 animals), demonstrating that healthy dairy cattle from farms in the Mid-West of Brazil are an important reservoir for highly pathogenic E. coli O157:H7.

Humoral Response of Buffaloes to a Recombinant Vaccine against Botulism Serotypes C and D

Botulism is a fatal intoxication caused by botulinum neurotoxins (BoNTs), which are mainly produced by Clostridium botulinum and characterized by flaccid paralysis. The BoNTs C and D are the main serotypes responsible for botulism in animals, including buffaloes. Botulism is one of the leading causes of death in adult ruminants in Brazil due to the high mortality rates, even though botulism in buffaloes is poorly reported and does not reflect the real economic impact of this disease in Brazilian herds. Vaccination is reported as the most important prophylactic measure for botulism control, although there are no specific vaccines commercially available for buffaloes in Brazil. This study aimed to evaluate the humoral immune response of buffalo groups vaccinated with three different concentrations of recombinant proteins (100, 200, and 400 µg) against BoNTs serotypes C and D as well as to compare the groups to each other and with a group vaccinated with a bivalent commercial toxoid. The recombinant vaccine with a concentration of 400 μg of proteins induced the highest titers among the tested vaccines and was proven to be the best choice among the formulations evaluated and should be considered as a potential vaccine against botulism in buffalo.

Immunogenicity of a Bivalent Non-Purified Recombinant Vaccine against Botulism in Cattle

Botulism is a potentially fatal intoxication caused by botulinum neurotoxins (BoNTs) produced mainly by Clostridium botulinum. Vaccination against BoNT serotypes C and D is the main procedure to control cattle botulism. Current vaccines contain formaldehyde-inactivated native BoNTs, which have a time-consuming production process and pose safety risks. The development of non-toxic recombinant vaccines has helped to overcome these limitations. This study aims to evaluate the humoral immune response generated by cattle immunized with non-purified recombinant fragments of BoNTs C and D. Cattle were vaccinated in a two-dose scheme with 100, 200 and 400 µg of each antigen, with serum sampling on days 0, 56, 120, and 180 after vaccination. Animals who received either 200 or 400 μg of both antigens induced titers higher than the minimum required by the Brazilian ministry of Agriculture, Livestock and Food Supply and achieved 100% (8/8) seroconversion rate. Animals vaccinated with commercial toxoid vaccine had only a 75% (6/8) seroconversion rate for both toxins. Animals that received doses containing 400 µg of recombinant protein were the only ones to maintain titers above the required level up until day 120 post-vaccination, and to achieve 100% (8/8) seroconversion for both toxins. In conclusion, 400 µg the recombinant Escherichia coli cell lysates supernatant was demonstrated to be an affordable means of producing an effective and safe botulism vaccine for cattle.