Increase in oxidized proteins in Theileria sergenti-infected erythrocyte membrane

As a part of the elucidation of the pathogenesis of anemia in Theileria sergenti infection, oxidized-erythrocyte membrane proteins (OEMPs) collected from T. sergenti-infected calves were examined. The amount of OEMPs were seen to increase with the progress of the anemia and showed a maximum value around the crisis period of the infection. The increase of OEMPs coincided with band Nos. 1, 2, 2.1, 3, 4.1, 5, 6, and 7. The majority of them was located at the Triton X-100 un-extractive phase, and was confirmed as cytoskeletal proteins. This evidence indicates the enhancement of erythrocytic oxidation, and suggests that it might be one of the aggravating factors of anemia in T. sergenti infection.     

Activation of bovine peripheral blood macrophages in Theileria sergenti-infected calves

Macrophage activation in Theileria sergenti-infected calves was studied by testing the production of oxygen metabolites in macrophages following specific and non-specific stimulation with T sergenti merozoites or zymosan, respectively. Six calves were inoculated with merozoites and three calves with sporozoites. All showed significant macrophage activation within one month after inoculation (P less than 0.05). Activation of macrophages appeared earlier than parasitaemia or the peak of antibody titre against T sergenti. The highest chemiluminescence response, indicative of macrophage activation, was observed when the merozoites were opsonised with immune sera.     

Cytokine and inducible nitric oxide synthase gene expressions in peripheral blood mononuclear cells and related clinical characteristics in Theileria orientalis sergenti-infected calves

Eight splenectomized calves were inoculated with Theileria orientalis sergenti (Tos)-infected tick gland homogenate (5 calves) or infected erythrocyte suspension (3 calves). Clinical characteristics were different in calves post-infection. Animals were divided into 3 groups on the basis of susceptibility as high, middle, and low. Increase in mRNA of IFN-gamma, IL-2, and TNF-alpha was observed in peripheral blood mononuclear cells at the peak of infection and was seen to be related with pyrexia and parasitemia. Expression of IL-1, IL-4, and inducible nitric oxide synthase was not observed. Decreased plasma nitrite/nitrate level was observed in the groups. The results of this study indicate that Th1 response is the predominant response in Tos infection, and this response is also related with their clinical characteristics.     

Age resistance to Theileria parva bovis infection in calves

Data collected in the Zimbabwean province of Mashonaland-West, in the period 1980-1988, showed that mortality in calves owing to Theileria parva bovis infection (January disease) was significantly lower in animals younger than 7 months than in older cattle. Groups of seven Holstein-Friesian calves from non-immune dams aged approximately 1, 4, 7, 10 and 13 months were infected with a Theileria parva bovis tick-derived stabilate. The dose chosen was lethal for 40% of the calves in the trial. Mortality was highest in the 4-month age group. The reactions in the 7-, 10- and 13-month age groups became progressively milder. The reactions in the 1-month old calves were the least marked, being very mild. The age-related resistance in the youngest calves, as can be concluded from our results, is only of short duration and cannot explain the lower incidence of January disease observed in calves in the field.     

Treatment of Theileria annulata infection in calves with parvaquone

Fifteen calves were infected by the injection of stabilate of a suspension of Hyalomma anatolicum anatolicum ticks infected with the Ankara strain of Theileria annulata. Three were kept untreated, as controls, and they all died of theileriosis. Three groups of four calves were treated intramuscularly with parvaquone (Clexon; Wellcome) when early signs of theileriosis were clinically apparent. One group received 20 mg (kg bodyweight)-1 of parvaquone 10 days after infection. Two of these calves were clinically cured and two died of theileriosis. The remaining two groups of four calves received two doses of parvaquone, each of 10 mg (kg bodyweight)-1, either on days 10 and 11 or days 10 and 12. Three calves in each group were clinically cured while one in each group died of theileriosis. Total parasitological cure was not achieved in any of the calves. No symptoms of toxicity due to parvaquone treatment were observed.     

Corpuscular oxidation in newborn crossbred calves naturally infected with Theileria annulata

Erythrocytic lipid peroxidation has been implicated as a cause of anemia in Theileria annulata infection in cattle. The present study aimed to evaluate oxidative damage of membrane lipids and proteins in addition to hemoglobin (Hb) as three criterions of erythrocyte oxidation and their relation to erythrocyte deformability and anemia of newborn crossbred calves (Friesian × Egyptian Balady breed) naturally infected with T. annulata. Twenty-five T. annulata-infected calves (aged 20-30 days) along with 15 age matched healthy controls were used. Percentage of parasitemia varied from 12% to 63% (34.76 ± 3.05%). In comparison to controls, infected calves showed increased levels (P<0.001) of lipid peroxidation (malondialdehyde; MDA, 52%) and protein oxidation (protein carbonyls; PCs, 132%) in erythrocyte membrane as well as increased values of Hb oxidation (methemoglobin; MetHb, 186%), corpuscular osmotic fragility (15.1%) and hemolysis (free Hb; 195.5%). Parasitemia was positively correlated with MDA (r=0.41, P=0.039), PCs (r=0.45, P=0.023) and MetHb (r=0.40, P=0.042). Also, percent of erythrocytic deformability (echinocytosis) was positively correlated with MDA (r=0.49, P=0.013) and PCs (r=0.63, P<0.001). On the other hand, erythrocytic packed cell volume was negatively correlated with MDA (r=-0.44, P=0.028), PCs (r=-0.72, P<0.001) and MetHb (r=-0.42, P=0.037). In conclusion, T. annulata infection is associated with a parasitic burden-dependant oxidative damage to the erythrocyte membrane protein and lipid contents in addition to Hb. This oxidative damage is linked to the morphological changes of the erythrocyte and may act as mechanisms contribute to pathogenesis of anemia in T. annulata infection in newborn calves.     

Prophylactic efficacy of buparvaquone in experimentally induced Theileria annulata infection in calves

The antitheilerial activity of buparvaquone (BW 720C) was evaluated in experimentally induced Theileria annulata infections in cross-bred male calves. T. annulata infections were induced by injecting a suspension of infected ground tick tissue suspension (GUTTS) equivalent to two ticks subcutaneously into each calf. Buparvaquone at a dose of 2.5 mg kg-1 body weight was given as a single injection (intramuscularly) on Day 0 (Group 1), Day 8 (Group 2) and Day 12 (Group 3) post-infection. The animals in Groups 4 and 5 were untreated and challenged controls, respectively. All of the recovered animals from Groups 1-4 were challenged with a lethal dose of T. annulata at 6 weeks post-infection. The immunized animals were resistant to the homologous challenge, which killed three of four control animals (Group 5); the controls showed typical antemortem and post-mortem lesions of theileriosis.     

Treatment of experimentally induced Theileria annulata infection in cross-bred calves with buparvaquone

Twenty cross-bred (Bos taurus X Bos indicus) calves, 7-21 days old, were infected by a ground-up tick supernate of Hyalomma anatolicum anatolicum infected with the Hisar isolate of Theileria annulata. Six calves acted as untreated controls and they all died of theileriosis within 17 days of infection. The remaining 14 calves were divided into Group A and B, each consisting of seven calves. All the calves of Groups A and B were treated intramuscularly with buparvaquone (BW 720C) on Day 11 post-infection, when clinical signs of theileriosis were apparent. Each calf received 2.5 mg BW 720 C kg-1 body weight as a single injection. In addition, each calf of Group B was given proprietary haematinics by intramuscular injection, daily for 12 days. In Group A, two calves died of cerebral theileriosis and five were clinically cured. However, four of these five calves later died of anaemia. In Group B, all the calves were clinically cured and none died during the observation period of 1 month. The parasitaemia declined to less than 1% within a fortnight of treatment. The initial declines in haemoglobin concentration and packed cell volume were halted and preinfection values were soon restored. No toxic signs attributable to treatment with buparvaquone were observed.     

Haematological and biochemical studies on experimental Theileria annulata infection in crossbred calves

Administration of ground-up tick tissue stabilate (0.75 tick equivalent) by the subcutaneous route to crossbred calves aged 1 week to 1 month led to the development of acute theileriosis. Haematological studies revealed significant progressive decreases in haemoglobin concentration, packed cell volume and red blood cell count, whereas the total leukocyte count showed an initial non-significant leukocytosis followed by a significant leukopenia. Analysis of serum revealed significant increases in levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine kinase and -glutamyltransferase, and in the concentrations of uric acid, blood urea nitrogen and bilirubin. The concentrations of total protein, albumin, glucose, cholesterol and calcium showed non-significant decreases, while phosphorus decreased significantly during the terminal stages of the disease.     

Activation of bovine peripheral blood monocyte and its suppressive effect on parasitemia in Theileria sergenti infected calves.

Activation of bovine peripheral blood monocytes and its suppressive effect on parasite growth was examined in Theileria sergenti-infected calves by using a rosette assay that detects changes in Fc receptor expression and by luminol-dependent chemiluminescence response. Monocyte activation preceded the peak of parasitemia but was depressed parallelly with the growth of the parasites. When four calves were treated with prednisolone, three showed a good correlation between the suppression of monocyte activity and an increase of parasitemia.     

Estimating erythrocyte glyceraldehyde-3-phosphate dehydrogenase by a new method.

A semi-quantitative fluorimetric assay for glyceraldehyde-3-phosphate dehydrogenase has been described. This method was applied to a number of animal species and correlates well with the standard spectrophotometric method.     

Effects of experimentally induced Theileria annulata infection on the pharmacokinetics of oxytetracycline in cross-bred calves

The effects of an experimental Theileria annulata infection on the intravenous (10 mg kg-1) pharmacokinetics of oxytetracycline (OTC) were investigated in crossbred calves. The serum concentration-time curve of oxytetracycline before and after the experimental infection was best described by an open two-compartment model. The experimental infection was induced by a subcutaneous administration of ground-up tick supernate (GUTS) equivalent to 30 Hyalomma anatolicum anatolicum ticks infected with Theileria annulata. It produced a definite temperature rise and symptoms of clinical disease in the calves. The haemoglobin, packed cell volume (PCV), white blood cell (WBC) counts and serum Cu, Fe and Zn concentrations decreased after onset of the infection. The distribution and elimination half-lives (t1/2 alpha and t1/2 beta), volume of the central compartment (Vc), AUC0-infinity, AUMC and mean residence time (MRT), were significantly reduced (P < or = 0.05) and the hybrid rate constants K12, Kel, K12/K21 ratio and total body clearance (ClB) of oxytetracycline were significantly (P < or = 0.05) increased after infection. The infection, however, had no effect on the C0, K21, apparent and steady-state volumes of distribution (Vd(area) and Vdss) of the drug. The above changes may necessitate changes in the dosage regimen of oxytetracycline used to treat Theileria infections in cattle under field conditions.     

Fatal cases of Theileria annulata infection in calves in Portugal associated with neoplastic-like lymphoid cell proliferation

This study was carried out to investigate fifteen cases of acute lethal infection of calves (≤ 4 months of age) by the protozoan parasite Theileria (T.) annulata in the south of Portugal. Calves developed multifocal to coalescent nodular skin lesions, similar to multicentric malignant lymphoma. Infestation with ticks (genus Hyalomma) was intense. Theileria was seen in blood and lymph node smears, and T. annulata infection was confirmed by isolation of schizont-transformed cells and sequencing of hypervariable region 4 of the 18S rRNA gene. At necropsy, hemorrhagic nodules or nodules with a hemorrhagic halo were seen, particularly in the skin, subcutaneous tissue, skeletal and cardiac muscles, pharynx, trachea and intestinal serosa. Histologically, nodules were formed by large, round, lymphoblastoid neoplastic-like cells. Immunohistochemistry (IHC) identified these cells as mostly CD3 positive T lymphocytes and MAC387 positive macrophages. A marker for B lymphocytes (CD79αcy) labeled very few cells. T. annulata infected cells in these nodules were also identified by IHC through the use of two monoclonal antibodies (1C7 and 1C12) which are diagnostic for the parasite. It was concluded that the pathological changes observed in the different organs and tissues were caused by proliferation of schizont-infected macrophages, which subsequently stimulate a severe uncontrolled proliferation of uninfected T lymphocytes.     

Antibody response of calves to a single infection of Fasciola gigantica determined by an indirect fluorescent antibody technique.

The antibody response of six calves infected with 500 metacercariae of Fasciola gigantica each was monitored throughout 30 weeks of infection using an indirect fluorescent antibody technique (IFA). In vitro excysted F gigantica were employed as the test antigen. All animals showed high antibody titres from two to six weeks post-infection. Thereafter the antibody titres diminished gradually. Although all the experimentally infected animals harboured fluke burdens at autopsy, most gave negative IFA tests from 22 weeks post infection onwards. Specific immunofluorescent staining occurred on the surface glycocalyx of the newly excysted flukes. It is likely that this glycocalyx provides one of the earliest antigenic stimuli for the host's immune reactions to fascioliasis.