N.E. Martins

Avaliação da resposta de antitoxinas beta e épsilon de Clostridium perfringens induzidas em bovinos e coelhos por seis vacinas comerciais no Brasil

The antibody response against beta and epsilon toxins of Clostridium perfringens was evaluated in cattle vaccinated with six commercial clostridial vaccines. Groups of six calves (6-7 months old) were vaccinated with each vaccine (T2 to T7), on days 0 and 42, with the recommended dose and route. Saline solution (T1) and a standard toxoid vaccine (T8) were used as negative and positive controls, respectively. On days 0, 42 and 56 post-vaccination (PV), blood samples were collected for antibody titration. Vaccines, as well as controls, were also injected into 8 rabbits each, on days 0 and 21, using half of the dose recommended for cattle. Rabbits were bled on day 35. Rabbit sera were tested as a pool per vaccine and cattle sera were tested individually against beta and epsilon toxins, by the serum neutralization test in mice. The vaccine T2 had antibody titers of 22.6 and 5.6 IU/ml and T4 had 11.2 and 7.0 IU/ml against beta and epsilon toxins in rabbits, respectively. The standard toxoid had a titer of 45.2 IU/ml against both toxins. In cattle, mean antibody titers against beta toxin on days 42 and 56 PV induced by T2 (1.15 and 8.0 IU/ml) were similar to those induced by the standard toxoid (2.02 and 10.3 IU/ml). T4 titers (0.73 and 4.54 IU/ml), were lower (P<0.05) than those obtained with the standard toxoid, but similar to T2 titers. On day 42, the standard toxoid had a mean titer (0.97 IU/ml) against epsilon toxin significantly higher (P<0.05) than that obtained with T4 (0.15 IU/ml) but similar to T2 mean titer (0.42 IU/ml). On day 56, T2 resulted in a significantly higher titer (4.27 IU/ml) (P<0.05) than that induced by T4 (0.68 IU/ml), but similar to the standard control (4.98 IU/ml). The other vaccines, as well as the saline solution, did not elicit antibody responses, neither in rabbits nor in cattle. T2 induced antibody titers against C. perfringens beta and epsilon toxins similar to those induced by the standard toxoid and higher than those induced by T4.

Mortalidade por "septicemia dos peixes tropicais" em tilápias criadas em consorciação com suínos

A rural property was observed for one year to obtain seasonal observations of Edwardsiella septicemia in tilapias (Oreochromis sp.) from an integrated fish farm (using pig excrements as food). Fifty tilapias on summer, forty-five on autumn, fifty-five on winter and one hundred and five on spring were collected and evaluated microbiologically for the presence of Edwardsiella tarda. Samples of the external surface (skin, gills and fin), intestines and muscle were analyzed. Fishes were transported alive to the laboratory, and maintained for five days for observation. The external signs observed were opacity of cornea, respiratory difficulty, disordered swimming, nodules on gills, hemorrhagic lesions under the skin and fins and incoordination of the posterior part of the body. In general, after three days of observation, the tilapias died. At necropsy, ascites with the distension of the celomatic cavity, hemorrhagic and necrotic lesions in the liver, spleen and kidneys were found. Hemorrhagic enteritis was observed in the gut tube. Edwardsiella tarda isolated presented the following biochemical profile: negative urea, sucrose, phenylalanine desaminase and malonate utilization, and positive indole, methyl red, H2S, motility, glucose with gas production and lysine decarboxylase. The mortality rates were 69.9% on spring, 63.6% on winter, 48.0% on summer and 40.0% on autumn, highest rates occurring on spring and winter (P<0,05).

Inspeção visual e avaliações bacteriológica e físico-química da carne de piramutaba (Brachyplatistoma vaillanti) congelada

Visual inspection and bacteriological and physico-chemical evaluations were carried out in frozen, eviscerated, and headless piramutaba (Brachyplatistoma vaillanti). Twenty samples composed by a pool of three fish from the two main wholesalers of Belo Horizonte, MG, were studied. Salmonella ssp. and Staphylococcus aureus were only found in samples of one wholesaler, representing that 10% of the samples were inappropriate for human consumption. The results confirmed the low incidence of these pathogens in piramutaba. The total volatile bases were in accordance and the pH values were not in accordance with the law requirements in 90% of the samples.

Avaliação do teste de imunodifusão mediante emprego do polissacarídeo "O" no diagnóstico da brucelose bovina

Agar gel immunodiffusion test (AGID) using the O-polysaccharide was compared with serologic tests used in brucellosis diagnosis in non-infected, infected and early vaccinated cattle with strain B-19, in order to differentiate vaccinal antibodies from those resulting of natural infection by Brucella abortus. None of the techniques can differentiate with absolute reliability the vaccinal antibodies from antibodies associated with natural infection to Brucella abortus. Moreover, the use of AGID with this objective would cause maintenance of infected animals in the herd.

Avaliação de vacinas contra Clostridium novyi tipo B

Avaliou-se a eficiencia de 13 vacinas comerciais contra clostridioses que continham em sua composicao Clostridium novyi tipo B, pela titulacao de antitoxina alfa em soro de coelhos e de bovinos vacinados e pelo teste de desafio direto em cobaias. As vacinas codificadas como T1 e T10 apresentaram, em coelhos, titulos de antitoxina alfa de 8 e 12UI/ml respectivamente, superiores ao nivel minimo de teste de 3,5UI/ml, recomendado para controle desse produto, e as vacinas T2 e T5, titulos de 2 e 3UI/ml, respectivamente. As vacinas T1, T2, T5 e T10 apresentaram niveis de antitoxina alfa detectaveis em bovinos, mas somente T1 e T10 induziram titulos compativeis com o nivel de teste. Pelo metodo de desafio direto em cobaias, as vacinas T1, T2, T5, T10 e T11 atenderam aos requisitos, protegendo todos os animais desafiados. Em sua maioria, as vacinas comercializadas no Brasil contra Clostridium novyi tipo B foram ineficientes em estimular titulos sorologicos compativeis com os niveis de teste recomendado para controle desse produto.

Viabilidade de Tritrichomonas foetus após congelamento com diferentes crioprotetores

The aim of this work was to evaluate the viabilitity of Tritrichomonas foetus cryopreservated with glycerol and dimethilsulphosyde (DMSO) at -196 degrees C. Samples of the protozoa were thaw two days and 6, 12, 18, and 26 months after freezing to be evaluated. In the time analyzed, the freezing was viable in 60% and 90% of freeze samples with glycerol at 10% and DMSO at 12%, respectively.