Virulence factors in Escherichia coli strains isolated from pigs in the Ribeirao Preto region, State of Sao Paulo, Brazil.

Three-hundred faecal swabs were obtained from pigs with diarrhoea in farms located in different areas of the Ribeirao Preto region in the State of Sao Paulo. One-hundred Escherichia coli strains were isolated and tested for production of thermolabile (TL) and thermostable (STRa and STb) enterotoxins, and for the presence of colonization factors F4, F5 and F6. The strains were also tested for sensitivity to 14 antibiotics and chemotherapeutic agents. Twenty-four Escherichia coli strains produced enterotoxin STb, 5 produced LT and 3 produced STa. In the mannose-resistant haemagglutination reaction, one strain reacted positively with sheep, chicken, horse and human red blood cells and another reacted positively with guinea pig, sheep, chicken, horse and human red cells. However, both strains were negative for colonization factors F4, F5 and F6 when submitted to the slide agglutination test. All Escherichia coli strains were resistant to at least one antibiotic, the highest percentages being obtained for resistance to penicillin, tetracycline and cephalotin. In addition to the importance of the virulence factors normally encountered in enterotoxigenic Escherichia coli strains from pigs, the present results show the possible existence of new colonization factors other than F4, F5 and F6 participating in E. coli-induced pigs colibacillosis in the Ribeirao Preto region.

Immunisation of dogs, hamsters and guinea pigs against Rhipicephalus sanguineus using crude unfed adult tick extracts

Naive experimental groups of dogs, hamsters and guinea pigs were inoculated three times subcutaneously with unfed adult extract of the tick Rhipicephalus sanguineus and challenged with adult R. sanguineus to evaluate resistance. The acquisition of resistance was based on alterations of some reproductive and feeding performance parameters of female ticks such as female and egg mass weights, engorgement, pre-oviposition and incubation periods, larval hatchability rate and efficiency rates of female ticks in converting their food reservoir to eggs and larvae. Dogs did not develop resistance under these experimental conditions; guinea pigs and hamsters, to a lesser extent, acquired an effective immunity to ticks as demonstrated by the impairment of the reproductive and feeding performance. However, the resistance induced by inoculation of the extract in the rodents seemed not to be as efficient as that induced by successive infestations.

Cutaneous hypersensitivity induced in dogs and guinea-pigs by extracts of the tick Rhipicephalus sanguineus (Acari: Ixodidae)

The cutaneous hypersensitivity induced by Rhipicephalus sanguineus tick extract in dogs (natural host) and guinea-pigs (laboratory host) was evaluated. The left ear of infested and control (tick-bite naive) dogs and guinea-pigs was injected intradermally with an extract from unfed adult ticks and the right ear with phosphate buffered saline (PBS). Ear thickness variations were then measured after 10 min and 1, 2, 6, 18, 24, 48, 72 and 96 h post-injection. Results were expressed as percentual changes in the ear thickness in relation to pre-inoculation values. The final variation in ear thickness induced by the extract was given by subtracting, in each animal, the right ear percentual increase from that of the left ear. Guinea-pigs were tested at two different times following infestation and with two different doses of extract. Infested guinea-pigs from the three experiments developed an immediate (within the first 2 h post-inoculation) and a strong delayed reaction (24 h) to the extract. Dogs, unlike guinea-pigs, developed only a strong immediate reaction whereby an 80% increase in ear thickness was observed. Control animals, with the exception of one dog, did not develop any significant reaction to the extract. Only mild reactions were induced by PBS in the right ear of all animals. The correlation between the absence of a strong delayed type reaction to tick extract and the lack of resistance of the natural host to R. sanguineus tick is discussed. © 1995 Chapman & Hall.

Toxoplasma gondii: Comparison of a rhoptry-ELISA with IFAT and MAT for antibody detection in sera of experimentally infected pigs

Indirect ELISA and IFAT have been reported to be more sensitive and specific than agglutination tests. However, MAT is cheaper, easier than the others and does not need special equipment. The purpose of this study was to compare an enzyme linked immunosorbent assay using crude rhoptries of Toxoplasma gondii as coating wells (r-ELISA) with indirect fluorescence antibody test (IFAT) and modified agglutination test (MAT) to detect anti-T. gondii antibodies in sera of experimentally infected pigs. Ten mixed breed pigs between 6.5 and 7.5 weeks old were used. All pigs were negative for the presence of T. gondii antibodies by IFAT (titre < 16), r-ELISA (OD < 0.295) and MAT (titre < 16). Animals received 7 × 107 viable tachyzoites of the RH strain by intramuscular (IM) route at day 0. Serum samples were collected at days -6, 0, 7, 14, 21, 28, 35, 42, 50, and 57. IFAT detected anti-T. gondii antibodies earlier than r-ELISA and MAT. The average of antibody levels was higher at day 35 in IFAT (Log10 = 2.9) and in MAT (Log10 = 3.5), and at day 42 in r-ELISA (OD = 0.797). The antibody levels remained high through the 57th day after inoculation in MAT, and there was a decrease tendency in r-ELISA and IFAT. IFAT was used as gold standard and r-ELISA demonstrated a higher prevalence (73.3%), sensitivity (94.3%), negative predictive value (83.3%), and accuracy (95.6%) than MAT. Kappa agreements among tests were calculated, and the best results were shown by r-ELISA × IFAT (κ = 0.88, p < 0.001). Cross-reaction with Sarcocystis miescheriana was investigated in r-ELISA and OD mean was 0.163 ± 0.035 (n = 65). Additionally, none of the animals inoculated with Sarcocystis reacted positively in r-ELISA. Our results indicate that r-ELISA could be a good method for serological detection of T. gondii infection in pigs. © 2005 Elsevier Inc. All rights reserved.

Toxoplasma gondii: Detection by mouse bioassay, histopathology, and polymerase chain reaction in tissues from experimentally infected pigs

In the present study, we evaluated three techniques, mouse bioassay, histopathology, and polymerase chain reaction (PCR) to detect Toxoplasma gondii infection in tissues from experimentally infected pigs. Twelve mixed breed pigs, seronegative for T. gondii using an indirect immunofluorescent antibody test (IFAT), were used. Ten pigs were infected with 4 × 104 VEG strain oocysts, and two were maintained as uninfected controls. Animals were killed 60 days pos infection. Muscle (heart, tongue, diaphragm, and masseter) and brain samples were collected to investigate the presence of T. gondii tissue cysts by the different assay methods. For the bioassay, samples of brain (50 g) and pool of muscle samples (12.5 g of tongue, masseter, diaphragm, and heart) were used. PCR was performed using Tox4 and Tox5 primers which amplified a 529 bp fragment. The DNA extraction and PCR were performed three times, and all tissue samples were tested individually (brain, tongue, masseter, diaphragm, and heart). For histopathology, fragments of tissues were fixed in 10% of buffered formal saline and stained with HE. Histopathological results were all negative. PCR showed 25/150 (16.6%) positive samples, being 17/120 (14.1%) and 8/30 (26.6%) from muscle, and brain tissues, respectively. Tissue cysts of T. gondii were identified by mouse bioassay in 54/98 (55.1%) samples, being 31/48 (64.6%) from muscle samples, and 23/50 (46.0%) from brain samples. Toxoplasma gondii isolation in muscle samples by mouse bioassay was higher than in PCR (P < 0.01). Results indicate that DNA from pig tissues interfered with 529-bp-PCR sensitivity, and mouse bioassay was better than PCR in detecting T. gondii in tissues from pigs. © 2006 Elsevier Inc. All rights reserved.

Efeito da adição de probiótico e/ou prebiótico em dietas de leitões desmamados sobre o desempenho, incidência de diarréia e contagem de coliformes totais

In the Experiment 1, 50 pigs weaned at the 21 days were fed with either of five diets: T1 - basal diet; T2 - basal diet + antibiotic; T3 - basal diet + probiotic; T4 - basal diet + prebiotic; T5 - basal diet + simbiotic. The variables studied were body weight, feed intake and feed conversion in the Phase 1 (21 to 43 days), Phase 2 (44 to 57 days), Phase 3 (58 to 70 days) and Total Phase (21 to 70 days). During the performance experiment, a fecal survey score was conducted to verify diarrhea incidence. In the Experiment 2, 44 pigs weaned at 21 days were fed with the same diets of Experiment 1. Pigs were slaughtered at three differents ages (at weaning, at seven and 14 days after weaning). A segment of the small intestine was collected for analisys of total coliformes. The results showed that the best performance was obtained with the utilization of prebiotic and simbiotic. There were not differences in relation to diarrhea incidence among the treatments studied. The addition of probiotic and/or prebiotic in the diet prevented increase of colonization by pathogenic bacterias from seven to 14 days after weaning.

Uso de probiótico em dietas de suínos: Incidência de diarréia, desempenho zootécnico e digestibilidade de rações

Two trials were conducted aiming to of evaluate the effect of probiotic supplementation in pig's diet: Trial 1: diarrhea incidence and performance; Trial 2: feed intake and digestibility. In the Trial 1, forty weaning barrow piglets were distributed in four treatments: T0-basal diet; T100-basal diet +100ppm of probiotic; T200-basal diet +200ppm e T300-basal diet +300ppm. The trial 2 was a digestibility trial, where eight barrow pigs were used, distributed in two treatments: T1-basal diet and T2-basal diet + 200 ppm of same probiotic used in the Experiment 1. In the Period 1 the animals of T0 and T100 groups showed higher diarrhea incidence (P<0.05) than the T200 and T300 groups. The performance of animals of T100 group were lower than other treatment groups (P<0.05). In the Period 2 the T200 and T300 animals, showed better FG ratio than the animals of T0 (P<0.05). In the total period it was not observed significative difference concerning performance, except for DFI. In the trial 2, the animals of treatment T2, showed an increase of feed intake when compared with animals of T1. Digestibility coefficients showed no significative differences among treatments. It was concluded that the addition of 200 and 300 ppm of probiotic in the Period 1 reduces incidences of diarrhea. But, in the total period of trial 1, the performance was similar among treatments. In the trial 2 it was observed better adaptation of animals receiving probiotics which was represented by higher feed intake.

Genetic diversity in wild (Sus scrofa scrofa) and domestic (Sus scrofa domestica) pigs and their hybrids based on polymorphism of a fragment of the D-loop region in the mitochondrial DNA

We examined the variation in mitochondrial DNA by sequencing the D-loop region in wild and domestic (large-white breed) pigs, in hybrids between domestic and wild pigs, and in Monteiro pigs. A D-loop fragment of approximately 330 bp was amplified by PCR. Sequencing of DNA amplicons identified haplotypes previously described as European and Asian types. Monteiro pigs and wild pigs had European haplotypes and domestic pigs had both European and Asian haplotypes. ©FUNPEC-RP.

Analysis of DNA damage induced by aflatoxin B1 in Dunkin-Hartley guinea pigs

Aflatoxin B1 (AFB1) is among the most potent naturally occurring carcinogens and classified as a group I carcinogen. Since the ingestion of aflatoxin-contaminated food is associated with several liver diseases, the aim of the present study was to evaluate the effect of 2, 20, and 200 ppb of AFB1 on DNA damage in peripheral blood lymphocytes and liver cells in Dunkin-Hartley guinea pigs. The animals were divided into four groups according to the given diet. After the treatment the lymphocytes and liver cells were isolated and DNA damage determined by Comet assay. The levels of DNA damage in lymphocytes were higher animals treated with 200 ppb of AFB1-enriched diet (P = 0.02). In the liver cells there were a relationship between the levels of DNA damage and the consumption of AFB1 in all studied groups. These results suggest that Comet assay performed on lymphocytes is a valuable genotoxic marker for high levels of exposure to AFB1 in guinea pig. Additionally our results indicate that the exposure to this toxin increases significantly and increases the level of DNA damage in liver cells, which is a key step on liver cancer development. We also suggest that the Comet assay is an useful tool for monitoring the genotoxicity of AFB1 in liver. © 2007 Springer Science+Business Media B.V.

Evaluation of IFA, MAT, ELISAs and immunoblotting for the detection of anti-Toxoplasma gondii antibodies in paired serum and aqueous humour samples from experimentally infected pigs

The study evaluated the efficiency of diagnostic laboratory methods to detect anti-Toxoplasma gondii antibodies in paired serum and aqueous humour samples from experimentally infected pigs. 18-mixed breed pigs were used during the experiment; these were divided into two groups, G1 (infected group, n = 10) and G2 (uninfected group, n = 8). Infection was performed with 4 × 10 4 VEG strain oocysts at day 0 by the oral route in G1 animals. All pigs were euthanized at day 60, when retina, aqueous humour, and blood samples were collected. Anti-T. gondii antibody levels were assessed in serum (s) and aqueous humour (ah) by indirect immunofluorescence assay (IFA), modified agglutination test (MAT), m-ELISA (using crude membranes from T. gondii tachyzoites as antigen) and r-ELISA (using rhoptries from T. gondii tachyzoites as antigen). Polymerase chain reactions (PCR) of samples from the retina were performed by using Tox4 and Tox5 primers. Antibody titers of G1 animals ranged from 128 to 1024 and from 16 to 256 in serum and aqueous humour, respectively. There were differences in the correlation coefficients between IFA(s) × IFA (ah) (r = 0.62, P = 0.05), MAT(s) × MAT (ah) (r = 0.97, P < 0.0001); however, there was no significant difference between r-ELISA(s) × r-ELISA (ah) (r = 0.14, P = 0.7). Antibodies present in serum and aqueous humour recognized similar antigens. Samples of retina were positive by PCR in 30% (3/10) of infected pigs. G2 animals remained without antibody levels and were PCR negative throughout the experiment. These results suggest that the use of a combination of tests and immunoblotting for paired aqueous humour and serum samples could improve the sensitivity and specificity for the diagnosis of ocular toxoplasmosis. © 2007 Elsevier Ltd. All rights reserved.

Leitões lactentes e desmamados alimentados com dietas farelada ou extrusada seca e umida

This work was conducted throughout three phases of swine's growth (7 days from birth till the weaning age; from weaning until 7 days later and from 8 to 21 days after weaning); taking as objective the evaluation of the development of suckling and weaned piglets fed with a bran or extruded, dried and wet diet. We've used, for this paper, a total number of 31 pigs breeds, weaned and in average 21 day's lifetime and 3 different rations: dried bran; dried extruded bran and wet extruded bran (2 volumes of water to one volume of ration). During the 8th and 21st day after weaning all the animals received the same bran dried ration. Water and ration were supplied ad libitum. The experimental delimitation was totally random, with 3 treatments and eleven repetitions in the two first phases and five repetitions in the third phase, the multivariate variance analysis applied in the inferences about the results and from this we could conclude that the weight daily gain and the ration daily consumption were significantly not affected, i.e. by the processing, by the dry material ration content. However, we could observe a tendency to increase ration consumption and weight gaining when the animals were fed with bran extruded wet ration.