Effects of probiotic bacteria at different concentrations on production of immunomodulatory antibodies against rabies virus in vaccinated cattle

This study evaluated the effects of supplementation with a combination of probiotic microorganisms, added at different concentrations to the mineral mixture, on the production of serum antibodies against rabies virus in cattle vaccinated with a single dose of rabies vaccine. Forty-two male Nellore cattle, aged 12 months, were randomly divided into three groups (n = 14): the control group (CG) received 70 grams of mineral mixture/animal/day; and the 2 gram probiotic group (G2P) and 8 gram probiotic group (G8P) received 70 grams of mineral mix/animal/day with 2 and 8 grams added, respectively, of a combination of probiotic microorganisms (Lactobacillus acidophilus, Streptococcus faecium, Bifidobacterium thermophilum and Bifidobacterium longum). Individual antibody titers were determined using a neutralization in cell-based rapid fluorescent focus inhibition test (RFFIT) technique. One-way analysis of variance (one-way ANOVA) was used with contrasts using the Tukey method to determine whether the experimental groups differed within each time point, and the paired t-test was used to determine whether differences occurred between time points within each group. The level of significance was set at 5%. There were statistically significant differences between the mean serum concentrations of the CG and G8P groups at 30 and 60 days after the first vaccination, and at 60 days, 100% of the animals maintained minimum titers of protective antibodies only in the G8P group. There was also improvement in the production of antibodies in the G2P group compared with the CG after 30 and 60 days, but this difference was not statistically significant. In conclusion, increasing doses of probiotic added to the mineral mix beneficially affected the rabies humoral immune response, as determined by serum antibodies, and enabled the maintenance of minimum protective titers for a longer period in previously vaccinated cattle

Chromium oxide (51Cr2O3 ) used as biological marker was not absorbed by fish / Óxido de crômio (51Cr 2O3 ), usado como marcador biológico, não é absorvido por peixe

The aim of this study was to evaluate the rate absorption of radio-labeled chromium oxide (51Cr2O3), used as biological marker in nutrition studies with Nile tilapia Oreochromis niloticus. An experimental diet with approximately 58 µCi of specific activity of the element was encapsulated and fed daily to 35 adult Nile tilapia; a group of 35 fish was used as control feeding on a basal diet. At the beginning of the experiment five fish from each group were randomly selected and blood samples were drawn from control (BC) and experimental fish (BE). Fish were then euthanized by anesthetic overdoses and samples of the liver tissue (LT), renal tissue (RT), stomach without content (S), intestine without content (I), gills tissue (GT), muscle tissue (fillet; MT), visceral fat (VF), content of the digestive tract (CTDE) and water aquarium were collected from the experimental fish. The procedure was repeated daily for one week. Simple linear regressions were adjusted - days of collection vs. determination coefficients, and were established for statistical comparisons of the measured activity of 51Cr readings in sampled blood and tissues (logarithmic transformation) for samples of the control and experimental fish. No differences (P>0.05) were detected between samples from BC fish and BE, RT, VF, MT and LT of treated fish, but samples of GT, I, S, CTDE and WA from the tanks holding fish which received the experimental diet differed from control (P<0.05). The experimental results indicate that the trivalent chromium in the form of 51Cr2O3 was not significantly absorbed by the gastrointestinal tract, gills or another possible route of absorption under these experimental conditions and with Nile tilapia. Therefore, this marker was shown to be inert and can be safely used in nutrition studies.

O objetivo deste estudo foi avaliar a taxa de absorção de radiomarcador óxido de crômio (51Cr2O3), utilizado como marcador biológico em estudos de nutrição, com tilápia-do-nilo Oreochromis niloticus. Uma dieta experimental com cerca de 58µCi de atividade específica do elemento foi encapsulada, e 35 adultos de tilápia foram alimentados diariamente; um grupo de 35 peixes foi usado como controle e alimentado com uma dieta basal. No início do estudo, cinco peixes de cada grupo foram selecionados aleatoriamente, e amostras de sangue foram coletadas dos peixes controle (BC) e experimentais (BE). Os peixes foram sacrificados por overdose de anestésicos, e amostras do tecido do fígado (LT), rins (RT), estômago sem conteúdo (S), intestino sem conteúdo (I), brânquias (GT), tecido muscular (filé; MT), gordura visceral (VF), conteúdo do trato digestivo (CTDE) e água do aquário (WA) foram coletadas somente dos peixes experimentais. O processo foi repetido diariamente durante uma semana. As regressões lineares simples foram ajustadas - dias de coleta versus coeficientes de determinação - e foram estabelecidas para comparações estatísticas da leitura das atividades medidas de 51Cr (transformação logarítmica) nas amostras dos peixes controle e experimentais. Não foram detectadas diferenças (P>0,05) entre as amostras BC dos peixes controle e BE, RT, VF , MT e LT dos peixes experimentais, mas as amostras de GT, I, S, CTDE e WA dos peixes que receberam a dieta experimental apresentaram diferença significativa em relação aos que receberam a dieta controle (P<0,05). Os resultados experimentais indicam que o crômio trivalente na forma de 51Cr2O3 não foi significativamente absorvido pelo trato gastrointestinal, pelas brânquias ou por outra via possível de absorção nessas condições experimentais e com tilápia do Nilo. Portanto, esse marcador demonstrou ser suficientemente inerte, o que torna seguro seu uso em estudos de nutrição.

Interval between first dose and booster affected antibody production in cattle vaccinated against rabies

In this study, we compared the levels of neutralizing antibodies induced by inactivated rabies vaccine in cattle by using three alternative immunization procedures. Forty-five bovines (breed nelore) were then organized in three groups (A, B and C, with 15 animals/group). Group A received only one vaccine dose at day zero and Group B received the first dose at day zero and then another dose at day 30 (early booster). Group C was also immunized with two doses; however, the booster was postponed until day 180 after the first dose (delayed booster). Blood samples were withdrawn at days zero (before the first dose) and 30, 210, 390, and 540 after the beginning of immunization and the antibody titers were evaluated by mouse neutralization test. The protocol used to immunize Group C (booster at day 180) was clearly more efficient. In this group, antibody levels were higher and also remained higher for longer periods in comparison with the other two groups. These results show that booster timing significantly affected antibody levels. Therefore, programs addressed to control this disease in cattle should consider not only the use of a booster but also its administration time

[Effect of freezing on immunogenicity of the rabies vaccine produced in suckling mouse brain]. / Efeito do congelamento sobre a imunogenicidade da vacina contra a raiva produzida em tecido cerebral de camundongo.

The immune humoral response induced by the rabies vaccine produced in suckling mouse brain was studied in 23 dogs. The mouse neutralization test (MNT) was used to evaluate the level of rabies antibodies. Ten dogs received vaccine stored at 2 to 8 degrees C, showing the following results: 30 days after vaccination, six samples (60%) responded to the MNT; 180 days after vaccination, 4 samples (40%); and 360 days after vaccination, only one sample (10%). The remaining 13 dogs received previously frozen vaccine and 30 days after vaccination, only two samples (l5.4%) responded to the MNT. No titers were detected 180 and 360 days after vaccination. Statistical analysis of each variable used Tuckey analysis of variance, which showed statistically significant differences between the two groups.

Efeito do congelamento sobre a imunogenicidade da vacina contra a raiva produzida em tecido cerebral de camundongo / Effect of freezing on immunogenicity of the rabies vaccine produced in suckling mouse brain

The immune humoral response induced by the rabies vaccine produced in suckling mouse brain was studied in 23 dogs. The mouse neutralization test (MNT) was used to evaluate the level of rabies antibodies. Ten dogs received vaccine stored at 2 to 8 degrees C, showing the following results: 30 days after vaccination, six samples (60%) responded to the MNT; 180 days after vaccination, 4 samples (40%); and 360 days after vaccination, only one sample (10%). The remaining 13 dogs received previously frozen vaccine and 30 days after vaccination, only two samples (l5.4%) responded to the MNT. No titers were detected 180 and 360 days after vaccination. Statistical analysis of each variable used Tuckey analysis of variance, which showed statistically significant differences between the two groups.

A resposta imune humoral induzida pela vacina contra a raiva produzida em cérebros de camundongos recém-nascidos foi estudada em 23 cães e o teste de soroneutralização em camundongos foi usado para avaliação dos níveis de anticorpos rábicos. Um grupo com 10 animais recebeu vacina conservada de 2 a 8oC e apresentou os seguintes resultados: após 30 dias da vacinação 6 (60%) amostras responderam ao teste; após 180 dias 4 (40%) e após 360 dias apenas 1 (10%). O outro grupo com 13 cães recebeu vacina previamente congelada e somente 2 (15,4%) amostras no dia 30 apresentaram resposta satisfatória; os demais períodos (180 e 360) após a vacinação, não foi encontrado título. A análise estatística dos dados referentes a cada uma das variáveis consideradas no estudo foi efetuada segundo a técnica de análise de variância seguida por Tuckey e indicaram diferenças estatisticamente significativas entre os grupos.