Effectiveness of treatment with lincomycin hydrochloride and/or vaccination against Mycoplasma hyopneumoniae for controlling chronic respiratory disease in a herd of pigs

A herd of pigs infected with Mycoplasma hyopneumoniae was used in a double-blind randomised trial to assess the effectiveness of three control strategies against chronic respiratory disease in growing-finishing pigs. One group of 61 pigs received 220 ppm lincomycin hydrochloride in the feed from day 71 to day 91, a second group was vaccinated against M. hyopneumoniae at four and 28 days of age, and a third group received both treatments; a fourth group was left untreated as a control. Throughout the nursery-finishing period (day 29 to slaughter) the average daily weight gain and feed conversion rate of all the treated groups were slightly better than in the controls, but there were no significant differences between them. There were no significant differences between the treated groups in terms of clinical signs, serology, pathology or mortality, which was very low throughout the trial.     

Pharmacokinetics of phenylbutazone in beef steers

Phenylbutazone was administered intravenously to a group of 11 beef steers at a dosage of 6 mg/kg of body weight. Whole plasma and protein-free plasma were analyzed for phenylbutazone residues. Pharmacokinetic parameters of total and free phenylbutazone in plasma were calculated using a noncompartmental method. In regards to whole plasma data, the mean volume of distribution at steady state (Vss), was 140 mL/kg body weight, with a mean (+/-SEM) terminal elimination half-life (t1/2) of 34 +/- 9 h. The mean clearance was 3.2 mL/h/kg body weight. The Vss, as determined from the protein-free plasma fraction, was 54093 mL/kg body weight. This larger Vss of free phenylbutazone compared with total plasma phenylbutazone was attributed to a high degree of plasma protein binding, as well as the greater penetration of free phenylbutazone into tissues. The mean t1/2 of free phenylbutazone was 35 +/- 12 h. This similarity to the t1/2 estimated from total plasma phenylbutazone data is attributed to an equilibrium between free and plasma phenylbutazone during the terminal elimination phase. The pharmacokinetic parameters of free and total plasma phenylbutazone in beef steers are statistically similar to those previously reported for lactating dairy cows.     

Mucosal and systemic isotype-specific antibody responses and protection in conventional pigs exposed to virulent or attenuated porcine epidemic diarrhoea virus

Eleven-day-old conventionally reared piglets were inoculated orally with two different doses of the cell-culture adapted strain CV-777 of the porcine epidemic diarrhoea virus (PEDV) or the virulent isolate of the same strain and challenged with the same virulent PEDV 3 weeks later. Pigs inoculated with the two doses of the attenuated virus did not show any typical sign of the disease, and virus shedding was not frequent. In contrast, 31% of pigs exposed to the virulent PEDV developed diarrhoea and virus shedding was demonstrated in 100%. At different postinoculation day (PID) and postchallenge day (PCD) virus-specific antibody-secreting cells (ASC) in gut associated lymphoid tissues (duodenum and ileum lamina propria and mesenteric lymph nodes) and systemic locations (blood and spleen) were assessed by enzyme-linked immunospot (ELISPOT). Only a small response was detected in the groups inoculated with attenuated PEDV, whereas in the group previously exposed to the virulent virus on PID 21 a large number of IgG and IgA ASC was detected. Isotype-specific antibody responses in serum were investigated by ELISA. IgG responses were detected in all groups, although the highest response corresponded to the group inoculated with virulent virus and only this group showed an IgA response. The pigs exposed to virulent PEDV were completely protected against the challenge with a higher dose of the same virulent virus on PID 21 and none of them shed the virus. The pigs inoculated with the attenuated strain were partially protected against the challenge, and 25% of the low dose- and 50% of the high dose-exposed pigs did not shed virus after challenge. All the pigs from a control group, not previously exposed to the virus, excreted the virus in faeces. A strong positive correlation was established between protection and the ASC responses detected in gut associated lymphoid tissues and blood at the challenge day and also between protection and serum isotype-specific antibody titers on that day. In addition, the IgA and IgG ASC responses detected in the blood on PID 21 also correlated with the responses found in the gut associated lymphoid tissues. The ASC and serum antibody responses after the challenge corresponded to a secondary immune response in the groups inoculated with attenuated virus, whereas a primary response was evident in the control group. No increase was seen in any of the parameters studied in the pigs inoculated with virulent PEDV.     

Characterization of a feline homologue of the alphaE integrin subunit (CD103) reveals high specificity for intra-epithelial lymphocytes

The characteristics of a feline homologue of the alphaE integrin (CD103), defined by two murine monoclonal antibodies, Fe7.1B8 (IgG1) and Fe7.2D8 (IgG1), are described. These antibodies recognized 75% of intra-epithelial (range 59-88%) and 40% of lamina proprial (range 28-46%) T cells of the intestinal mucosal tissue of the small intestine in contrast with approximately 2% of peripheral blood lymphocytes. Both antibodies immunoprecipitated a 180 kDa protein from biotinylated feline intra-epithelial mucosal leukocytes consistent with the alphaE integrin subunit in conjunction with a 120 kDa protein consistent with the beta7 subunit. The nucleotide sequence of feline alphaE integrin, generated from molecular cloning of the feline alphaE encoding cDNA, is also reported. This feline molecule shares 72% sequence homology with human and 69% homology with murine and rat counterparts. Homology includes the presence of an X (extra) domain, that appears unique to alphaE molecules as described for human, rat and mouse, as well as areas of homology common to other alpha integrins. Of note is a typical I (inserted) domain, the presence of seven repeat regions, and highly conserved sequences in the cytoplasmic tail. Transfection studies demonstrated that both antibodies recognized an extracellular component which encompassed the X and I domains of the cloned alphaE integrin subunit. These studies demonstrate that the pattern of tissue distribution, biochemical characteristics, and cDNA sequence of the feline alphaE integrin subunit are largely similar to that described for other species.     

A rapid and simple method for the separation of pure lymphocytes from horse blood

A method for the separation of pure and viable lymphocytes and granulocytes from the same blood sample in horses was reported. By centrifuging equine heparinized blood at 100 xg for 10 min at room temperature (r.t.), the resulting supernatant plasma was an almost pure (97.71 +/- 0.30%; n = 15) suspension of highly viable (98.72 +/- 0.28%) lymphocytes. When sodium citrate was used as an anticoagulant, lymphocyte suspensions collected in the same manner showed lower purity (87.89 +/- 1.59%; n = 9) and higher yields (56.56 +/- 3.89%, n = 9 versus 36.11 +/- 2.23%, n = 15). Where needed, a further centrifugation at 250 xg for 3 min (r.t.) of heparinized lymphocyte preparations removed an average of 87.39% (n = 15) contaminating platelets. A suspension of 85.96 +/- 2.20% pure granulocytes (93.23 +/- 1.74% neutrophils; n = 14) with minimal contamination by erythrocytes and high viability (93.11 +/- 1.26%) was obtained by performing a flash red blood cell lysis on the white-greyish layer resulting from the centrifugation of the heparinized blood samples. Among the several methods available, the procedure described herein is easy, rapid, cheap and reproducible.     

Possible Anxiolytic Effects of Ivermectin in Rats

Ivermectin, a mixture of 22,23-dihydroavermectin B_1a (80%) and B_1b (20%), is produced by Streptomyces avermectilis, an actinomycete. It is a macrocyclic lactone disaccharide, a member of the avermectin family, and is used as an antiparasitic drug. Previous studies performed in our laboratory showed that doramectin, another avermectin drug, interferes with GABAergic-related behaviours, leading to anxiety and seizures. The objective of the present study was to examine the effects of ivermectin (0.5 and 1.0 mg/kg) on the central nervous system of rats, using behavioural models related to GABAergic neurotransmission. A known anxiolytic drug, diazepam, was used as a positive control. Open field and elevated plus-maze behaviours, as well as conflict behaviour to a conditioned response, were assessed. The effects of ivermectin and diazepam in reversing the anxiety induced by picrotoxin was studied. The protective effects of ivermectin on pentylenetetrazole- and picrotoxin-induced seizures were also investigated. In the open field, 1.0 mg/kg ivermectin decreased locomotion frequency at 15 and 60 min of observation, rearing behaviour showed a biphasic effect at 15 and 30 min and duration of immobility was increased in all sessions after 1.0 mg/kg ivermectin. These data suggest anxiolytic or sedative effects. Ivermectin and diazepam both had a tendency to cause an increase both in the number of entries into the open arms and on the time spent in the open arms of an elevated plus-maze. Picrotoxin on its own reduced the number of entries as well as the time spent in the open arms. Both diazepam and ivermectin reversed these effects of picrotoxin. In conflict behaviour analysis, ivermectin and diazepam gave the classic effect of an anxiolytic drug, reversing the conditioned response to shock. Ivermectin protected rats from the convulsant effects of pentylenetetrazole but not from those of picrotoxin. Thus, ivermectin had the pharmacological profile of an anxiolytic drug with GABAergic properties. The lack of effect on seizures induced by picrotoxin suggests that the action of ivermectin is different from that of the benzodiazepine drugs.     

Response of Corriedale and Crioula Lanada Sheep to Artificial Primary Infection with Haemonchus Contortus

Clinical, parasitological and biochemical parameters were evaluated in Corriedale and Crioula Lanada sheep after a single experimental infection with Haemonchus contortus. Ten 4-month-old worm-free lambs, of each breed, were infected with 200 L₃ H. contortus per kg live weight and four uninfected animals of each breed were used as controls. Every week, the animals were weighed and blood and faecal samples were collected for measurement of packed cell volume (PCV), total serum protein (TSP) and albumin (ALB), and the number of eggs per gram of faeces (EPG), respectively. Twelve weeks after infection, the animals were slaughtered. The worm burden was determined and samples of the abomasal mucosa were processed for determination of the number of eosinophils, mast cells and globule leukocytes. No significant differences in PCV, TSP, ALB, parasite burden or the cell populations of the abomasal mucosa were observed between breeds, but Crioula lambs had a lower EPG count. The comparison of the infected groups with their respective controls revealed significant alterations in PCV, TSP and ALB in the Corriedale lambs and in PCV, TSP, ALB and the density of eosinophils and mast cells in the Crioula lambs.     

Evaluation of 65% permethrin spot-on for prevention of canine visceral leishmaniasis: effect on disease prevalence and the vectors (Diptera: Psychodidae) in a hyperendemic area

A study was designed to examine the effect of 65% permethrin spot-on on the prevalence of canine visceral leishmaniasis and the abundance of sand flies in two neighborhoods in Corumbá, Mato Grosso do Sul, Brazil known to have a high prevalence of visceral leishmaniasis. An enrollment survey was conducted to determine the prevalence of visceral leishmaniasis. Area residents were provided with information about the project; the study area was defined, and all dogs (160 in Cristo Redentor and 230 in Popular Velha) identified in the study area were enrolled. Three 65% permethrin spot-on treatments (June 15-25, July 13-15, and August 10-12) were administered to 150, 110, and 99 dogs, respectively, in Popular Velha, according to label recommendations. Dogs in Cristo Redentor were untreated controls. Visceral leishmaniasis was diagnosed periodically by indirect immunofluorescence assay. A reduction in canine visceral leishmaniasis prevalence was observed at the Popular Velha site. The infection rate for treated dogs 1 month following the final treatment was approximately 50% reduced from that observed before treatment(19.3% vs 9.6%). Conversely, the infection rate at the control site was more than 80% higher at the September sampling than that observed pretreatment (4.1% vs 7.4%). Similar numbers of sand flies were captured and identified from both sites throughout the study. The results suggest that regular use of 65% permethrin during months of high risk for canine visceral leishmaniasis can be a useful strategy for reducing the prevalence of this disease in hyperendemic areas. It should be stressed, however, that the success of this strategy depends not only on the efficacy of the product itself but also on the adoption of other control measures and on economic variables, considering the low purchasing power of the populations living in higher-risk neighborhoods.     

Antibody-induced internalization of viral glycoproteins in pseudorabies virus-infected monocytes and role of the cytoskeleton: a confocal study

Addition of pseudorabies virus (PrV)-specific polyclonal immunoglobulins to PrV-infected monocytes induces internalization of plasma membrane anchored viral glycoproteins. This process may interfere with antibody-dependent cell lysis and resembles the well-studied physiological endocytosis process. A confocal study was designed to investigate whether the major cellular components, involved in physiological endocytosis (clathrin, actin, dynein and microtubules), play a role in this virological internalization process. In order to visualize the interaction of endosomes, which contain the internalized viral glycoproteins, with clathrin, actin, dynein and microtubules, a double labeling of viral glycoproteins and different cellular proteins was performed. Porcine monocytes were inoculated with the PrV-strain 89V87 at a multiplicity of infection of 50 for 13h. After the addition of FITC-labeled porcine polyclonal PrV-specific antibodies, cells were fixed with para-formaldehyde at different time points and afterwards permeabilized. The different cellular components were visualized with monoclonal antibodies and a Texas Red-conjugate, with the exception of actin, which was stained with phalloidin-Texas Red. The cells were analyzed by confocal microscopy. A clear co-localization was observed between the viral glycoproteins and clathrin and dynein during the internalization process. The microtubules were in close contact with the internalized vesicles. For actin no co-localization could be observed. It can be stated that clathrin, dynein and microtubules, important components during physiological endocytosis, are also of importance during the antibody-induced internalization of viral glycoproteins.