Upregulation of sialyltransferases ST3Gal1 and ST6Gal1 promotes stabilization of erythrocyte mass and recovery of anemia in Trypanosoma brucei brucei-infected pigs.

The role of Sialyltransferases (STs) specifically subfamilies ST3Gal1 and ST6Gal1 tissue expression was investigated in the liver and kidney of Trypanosoma brucei brucei-infected and uninfected control pigs. The study was aimed to provide emerging target for treatment. Pigs were experimentally infected with 2 × 106 T. b. brucei (Federe strain); parasitemia was monitored by microscopy and tissue expression levels of ST3Gall and ST6Gall in the liver and kidney were assessed using quantitative real-time polymerase chain reaction (qRT-PCR). Parasitemia were undulating and anemia occurred significantly (P < 0.01) on day 13 in the infected pigs with an attempt to recover toward the termination of the study on day 21. The gene expressions for hepatic and renal ST3Gal1 and ST6Gal1 were significantly (P < 0.0001) upregulated 5-42 folds in the infected pig compared to the non-infected control group. It was concluded from the findings in this study that increased tissue expression of ST3Gal1 and ST6Gal1 in T b. brucei-infected pigs may play a pivotal role in the resialylation of desialylated red blood cells, thereby promoting recovery of the red blood cells and stabilization of erythrocyte mass in trypanosome-infected pigs. It is recommended that the expression of serum ST3Gal1 and ST6Gal1 be investigated further, in trypano-susceptible against trypano-tolerant breeds of animals to determine the role of these genes in trypano-tolerance.

Survey of bovine trypanosomosis in the Kachia Grazing Reserve, Kaduna State, Nigeria.

This study assessed the prevalence of trypanosomes in cattle at the Kachia Grazing Reserve (KGR) in March and June 2004 and in February 2005. A total of 1293 cattle blood samples were collected at random. The samples were analysed using the buffy coat technique and Giemsa thin blood films for parasite detection and identification. The effects of herd pen location to watering and grazing point's distances (using the global positioning system (GPS)) were determined and mean Packed cell volume (PCV) assessed. Overall, the detected prevalence of trypanosomosis was 8.4%, much higher than the previous prevalence of 5.3% before the present study was conducted. The prevalences in the months of March, June (2004) and February (2005) were 2.3%, 11.6% and 15.4%, respectively. Increased prevalence was associated with proximity of herd pens to watering point's distances (chi(2) for linear trend=4.447, P<0.05), but no association of herd pens to grazing point distances (chi(2)=2.186, P>0.05); suggesting that hydrological network played an important part in trypanosomosis transmission. The mean PCV of parasitaemic and apparasitaemic cattle were respectively 25.99+/-1.82% and 29.31+/-1.70%. The drop in mean PCV was most in 0-1-year age group, 23.47+/-3.10% and was statistically significant (P<0.05), suggesting that anaemia was most pronounced in this age group. Factors that may have contributed to the increased prevalence obtained were collapse of control measures and breed susceptibility. Since, Zebu cattle were the predominant breeds in the reserve, the study advocates effective use of insecticide impregnated screens (traps and targets) with community participation in mind for sustainability. If government intervenes through PATTEC ground spraying of insecticides in the reserve is recommended. In addition, chemotherapeutic and chemoprophylaxis should be systematically used to fight the problem of trypanosomosis in the KGR towards improved livestock production.

Studies on effects of lactose on experimental Trypanosoma vivax infection in Zebu cattle. 2. Packed cell volume.

The ability of intravenously administered lactose in normal saline to prevent a decline in packed cell volume (PCV) during experimental trypanosomosis was studied in Zebu cattle. During the lactose infusion period, the PCV was stable up to Day 5 post-infection (p.i.) in a lactose-infused group, compared to that in an uninfused group in which the PCV dropped significantly (P < 0.05) as shown by the values of cumulative percentage change. Furthermore the mean rate of change in PCV was significantly (P < 0.05) higher in the uninfused group relative to the lactose-infused group during the same period. While the PCV fell markedly in the lactose-infused group a day after lactose infusion was stopped (Day 13 p.i.), subsequent PCV values were significantly (P < 0.05) higher compared to those in the uninfused group, up to the end of experiment on Day 17 p.i. However the mean rates of change in PCV did not vary significantly (P > 0.05) between the groups during the period in which lactose infusion was stopped. The mean levels of parasitaemic waves and parasitaemia were higher, more prolonged and more frequent in the lactose-infused group. It was inferred that the lactose was able to prevent an early onset of anaemia in the Trypanosoma vivax-infected Zebu cattle.

Studies on effects of lactose on experimental Trypanosoma vivax infection in Zebu cattle. 1. Plasma kinetics of intravenously administered lactose at onset of infection and pathology.

Lactose in normal saline was administered intravenously to a group of Zebu cattle infected with Trypanosoma vivax to determine the blood plasma kinetics at onset of an experimental infection and its ability to protect tissues against damage as part of preliminary studies to determine its suitability for use in the treatment of trypanosomosis. Significantly (P < 0.01) higher lactose concentrations were observed in the T. vivax-infected bulls at 30 min and 1 h (P < 0.05) post-infection (p.i.) and by 4 h p.i. the plasma lactose remained above the level prior to infusion, after which it fell slightly below the pre-infusion level in the uninfected group. Calculated pharmacokinetic parameters revealed delayed excretion of lactose in the T. vivax-infected group soon after infection. The total body clearance (Cl(B)) was significantly (P < 0.05) reduced. The biological half-life (t1/2), elimination rate constant (k(el)) and apparent volume of distribution (V(d)) were relatively decreased (P > 0.05) as a result of the T. vivax infection. Retention of lactose in the plasma was attributed to decreased plasma clearance. It is suggested that the presence of trypanosomes in circulation rather than organic lesions could have been responsible for the delay observed in the excretion of lactose. At 12 weeks p.i., when the experiment was terminated, the group infected and given lactose infusion (despite higher parasitaemia) had no gross or histopathological lesions in the brain, spleen, lymph nodes, heart, kidneys, liver and testes. However, the group infected but not infused with lactose were emaciated, had pale mucosae, watery blood, general muscular atrophy, serous atrophy of coronary fat and other adipose tissue, hepatomegaly, splenomegaly, swollen and oedematous lymph nodes, all of which are suggestive of trypanosomosis. Histopathological lesions included narrowing of Bowman's space and hypercellularity of glomerular tufts in the kidneys with the mean glomerular tuft nuclear indices (GTNs) in the group significantly higher (P < 0.01) than the mean GTNs of the lactose-infused and control bulls. Degenerative changes occurred in the myocardium, spleen, testes and epididymides. The tesicular and epididymal lesions are indicative of male reproductive dysfunction.

Sequential testicular and epididymal damage in Zebu bulls experimentally infected with Trypanosoma vivax.

Six Zebu bulls aged between 31 and 34 months exhibiting good libido were used to study sequential testicular and epididymal damage in Trypanosoma vivax infection. Three bulls were infected with T. vivax, while the other three served as controls. All infected bulls became parasitaemic by day 5 post-infection and developed clinical trypanosomosis with rapidly developing anaemia. Representative bulls, one from each of the infected and control groups, were sacrificed on days 14, 28 and 56 post-infection. Testes and epididymides from these animals were studied histopathologically after processing and staining with haematoxylin and eosin (H and E). Testicular degeneration developed in all the infected bulls characterized by depletion of spermatogenic cells and destruction of interstitial tissue. The most severe testicular degeneration occurred in the bull that was sacrificed 56 days post-infection. Epididymal sperm reserves were 36%, 4% and 0%, respectively, in infected bulls that were sacrificed on days 14, 28 and 56 post-infection. The 0% epididymal sperm reserve may suggest complete cessation of spermatogenesis. It was concluded from this study that T. vivax infection of Zebu bulls could cause severe testicular and epididymal damage that may result in infertility or even sterility of the affected animals at early infection stages not previously thought.

Haemagglutination inhibition antibodies, rectal temperature and total protein of chickens infected with a local Nigerian isolate of velogenic Newcastle disease virus.

Changes in values of haemagglutination inhibition (HI) antibody titre, rectal temperature (RT) and total protein (TP) were determined for Shaver Brown chickens infected with Newcastle disease virus (NDV) Kudu 113. The infected chickens came down with Newcastle disease by day 3 post infection (PI). The major clinical signs were depression, greenish diarrhoea, paralysis of legs and wings, opisthotonus and torticolis. Mortality and morbidity were 52% and 1000%, respectively. There were haemorrhagic lesions in the wall of the intestine, proventricular mucosa and caecal tonsils. There were necrosis and mononuclear cell infiltration of the liver, kidney and spleen. There was a significant increase in daily mean HI antibody titres from days 3 to 9 PI. Similarly, significant rise in daily mean RTs were noticed in the infected chickens from days 1 to 13 PI. On the other hand, there was a decrease in daily mean TP concentrations of infected chickens, beginning from day 3 PI, and the lowest concentration of 2.60 +/- 0.15 g/dl was obtained by days 7 and 11 PI. The values of HI, RT and TP for the control chickens were relatively constant during the experiment. The correlation coefficient (r) between HI and RT was positive and highly significant (r = 0.725, p<0.001), while the relationship between HI and TP was negative but highly significant (r = -0.712, p<0.001). It was concluded that NDV Kudu 113 induced increases in values of HI and RT, which occurred concurrently with a decrease in TP concentrations of infected chickens.

Depleted serum haptoglobin in acute bovine trypanosomiasis.

Haemoglobin-binding protein (Haptoglobin, Hp) was assayed in the sera of control and zebu calves with acute T. vivax infection. Hp in control Zebu calves ranged between 123.5 and 236.5 mg dl-1 while Hp in the infected calves was too low to measure or absent. It was suggested that absence of Hp in the infected calves may be as a result of gradual intravascular haemolysis and removal of the Hp-Hb complex by the reticuloendothelial system.

Studies of experimental infection and cross-immunity between stocks of Cowdria ruminantium in Sokoto red goats.

The course of experimental infection and cross-immunity tests between stocks of Cowdria ruminantium were investigated using eight infected and four uninfected control Sokoto red goats. All eight infected goats reacted to the primary infection. The incubation period varied between 8 and 23 days. During the febrile reaction, the highest rectal temperature recorded was 40 degrees C and the lowest was 39.7 degrees C, compared with a range of 38.6 +/- 0.15 to 38.1 +/- 0.19 in control goats. Following the primary infection, each of the animals was treated with long-acting Tetracycline (Terramycin, Pfizer) at a dose of 20 mg kg-1 body weight to control the resulting temperature reaction. They were reinfected with the homologous stock 3 weeks after treatment to demonstrate whether they had become immune. The homologous challenge did not give any temperature reaction during 3 weeks of monitoring. They were then challenged with the heterologous C. ruminantium stock. This did not result in a febrile reaction during 3 weeks of monitoring. The observed cross-protection indicates antigenic similarity between the two stocks.

Studies of infectivity and pathogenicity of an isolate of Trypanosoma evansi in Yankasa sheep.

The course of experimental infection and pathogenicity of an isolate of Trypanosoma evansi were investigated using eight infected and six uninfected control Yankasa sheep. The sheep were each infected intravenously via the jugular vein with approximately 2.0 x 10(6) T. evansi parasites. The effects of the parasite on body temperature, packed cell volume (PCV), haemoglobin, erythrocytes, total protein, were monitored three times a week for approximately 9 weeks. Body weights were determined once every week for the duration of the experiment. The results showed that all the infected sheep were positive for the parasite. The prepatent period varied between 3 and 6 days. T. evansi produced parasitaemic waves at an average of 8.3 days interval. Two distinct forms of the disease were produced namely, acute (4-14 days postinfection), and chronic (43-59 days postinfection). Anaemia was a distinct feature of the disease. While the mean rectal temperatures were significantly elevated (P < 0.05), the mean values of the haematological parameters of the infected sheep dropped significantly (P < 0.05) compared to the preinfection levels. Observed clinical signs included pale mucous membrane, epiphora, loss of appetite, emaciation, dullness and rough hair coat together with fluctuating pyrexia which in most cases coincided with rise in parasitaemia. It is suggested that the isolate of T. evansi is pathogenic for Yankasa sheep.

Increased susceptibility of erythrocytes to in vitro peroxidation in acute Trypanosoma brucei infection of mice.

Trypanosoma brucei, Wamba strain, produced an acute infection in mice, and mortality was observed 2 days after the onset of parasitaemia which occurred 3-5 days postinfection. Anaemia was observed in the tail blood of the survivors. When washed erythrocytes from the heart blood were incubated in physiological saline containing 1.5% hydrogen peroxide, the erythrocytes of the infected mice produced significantly greater amounts of by-products of lipid peroxidation (measured as thiobarbituric acid reactive substances) than the erythrocytes of the control mice. This observation suggested that the infected mice may have a reduced ability in the prevention of free radical mediated lipid peroxidation in the erythrocyte membrane. It is concluded that peroxidative injury to the erythrocytes may contribute to the pathogenesis of anaemia in trypanosomosis.

Effect of acute Trypanosoma vivax infection on cattle erythrocyte glutathione and susceptibility to in vitro peroxidation.

During acute Trypanosoma vivax infection of calves, produced by intravenous inoculation, the mean packed cell volume and red blood cell counts of the infected animals decreased significantly (P < 0.05) between Days 6 and 13 post-infection (pi). The moderately severe normocytic anaemia started to develop during the first wave of parasitaemia which occurred from Day 2 pi and peaked between Days 4 and 5 pi. The mean erythrocyte glutathione (GSH) concentration of the infected calves decreased significantly (P < 0.05) from 58.4 +/- 11.4 mg 100ml-1 red blood cells (RBC) on Day 0 pi to 44.5 +/- 12.8 mg 100ml-1 RBC on Day 5 pi. As the GSH values recovered on Day 6 pi and increased thereafter, another slight decrease (P > 0.05) in GSH concentration occurred on Day 12 pi at the second peak of parasitaemia followed by a significant (P < 0.05) increase to 79.1 +/- 14.6 mg 100ml-1 RBC on Day 13 pi. In the uninfected calves, the mean GSH values ranged from 47.7 +/- 7.0 to 60.8 +/- 6.8 mg 100ml-1 RBC. When washed, erythrocytes of the infected and uninfected calves were separately challenged with hydrogen peroxide. They produced comparable amounts of thiobarbituric acid reactive substances as a measure of by-products of lipid peroxidation. This suggested that the ability of the erythrocytes to prevent peroxidative injury was not reduced, because GSH regeneration was probably enhanced and the antioxidant capacity of the erythrocytes was maintained.

Effects of acute bovine trypanosomosis (Trypanosoma vivax) on plasma kinetics of intravenously administered lactose.

Four calves infected with Trypanosoma vivax and four uninfected control calves were each injected intravenously with repeated doses of 0.5 g lactose kg-1 body weight, thrice daily at intervals of 4 h. Plasma samples were collected at specified time intervals and analysed for lactose. Pharmacokinetic parameters were calculated from the data. T. vivax infection delayed excretion of lactose from the body, thus leading to significantly (P < 0.001) increased biological half life (t1/2) and a significantly (P < 0.001) reduced elimination rate constant for lactose in the body. The apparent volume of distribution and total clearance of lactose were not affected by the infection. T. vivax infection also appeared to cause accumulation of lactose in the plasma after repeated intravenous administration.

Trypanosoma vivax, stock V953: inhibitory effect of type A influenza virus anti-HAV8 serum on in vitro neuraminidase (sialidase) activity.

Trypanosoma vivax stock V953 lysates were observed to produce neuraminidase (sialidase EC 3.2.1.18) in vitro, which cleaved neuraminic (sialic) acid from the substrate fetuin. The neuraminidase activity was proportional to the number of trypanosomes in the lysates, with 0.44, 0.88, and 1.75 X 10(6) trypanosomes producing 1.4 +/- 0.06, 3.1 +/- 0.1, and 6.7 +/- 0.1 micrograms of sialic acid liberated, respectively. Equal numbers of unlysed and lysed trypanosomes produced approximately the same amount of the enzyme. Trypanosome eluates stored at room temperature appeared to have lost neuraminidase activities within 4 days. An inhibition test for identifying the neuraminidase antigen on influenza viruses was performed in vitro on the T. vivax lysates. The inhibition test, using Type A influenza virus anti-HAV8 serum, showed a highly significant (P less than 0.0001) reduction in neuraminidase activities. The effect of equal amounts of influenza antiserum on serially diluted trypanosome lysates showed that 1 ml of influenza anti-HAV8 serum would inhibit a mean of 6.74 +/- 0.18 micrograms of T. vivax stock V953 neuraminidase activity.

Leukocyte response in experimental Trypanosoma vivax infection in cattle.

Eight Zebu cattle were infected with Trypanosoma vivax stock Y58, while 8 served as uninfected controls. The infected animals developed early leukopenia due to concomitant lymphopenia and neutropenia. It is suggested that an increase in trypanosomal antigens and neuraminidase in the infected cattle at this time may have an effect on peripheral leukocytes.

In vitro magnesium- and calcium-induced sialidase activity in caprine intestinal mucosa cells.

Sialidase activity identical to 0.0196 mg per ml of liberated sialic acids (2.11 Units) was detected in small intestinal contents of goats. Mg++ and Ca++ induced in vitro detection in mucosa cells of both small and large intestines. Magnesium alone induced sialidase activities identical to 0.0128 mg per ml of liberated sialic acids (1.38 Units) and 0.0166 mg per ml (1.79 Units) in small and large intestinal mucosal cells, respectively. Mg++ and Ca++ together induced higher sialidase activities identical to 0.0191 mg per ml (2.06 Units) and 0.0194 mg per ml (2.09 Units) in small and large intestinal mucosal cells, respectively. The enzyme activity was slightly higher in large than in small intestinal mucosal cells. The results are discussed in relation to control of African animal trypanosomiasis.

Erythrocyte sialic acid in human sickle-cell disease.

Membrane-bound erythrocyte surface sialic acid concentrations in sickle-cell human patients (SS) and in control patients with sickle-cell trait (AS) and normal genes (AA) were assayed. The erythrocyte sialic acid concentration was significantly (P less than 0.001) higher in sickle-cell patients than in non-sicklers and although the concentration was higher in AS than AA individuals the difference was not significant (P greater than 0.05). The anaemic state of the SS patients was shown by a significantly (P less than 0.001) lower PCV than in non-sicklers. This finding is discussed in relation to membrane toughness and subsequent membrane loss leading to irreversible sickling of red cells in the deoxygenated state.

Erythrocyte surface sialic acid in Ndama and Zebu cattle.

Erythrocyte surface sialic acid concentrations were measured in the trypano-tolerant Ndama and trypano-susceptible Zebu breeds of cattle. All animals were uninfected and had no records of previous exposure to infection by African pathogenic trypanosomes. Ndama adults had significantly (P less than 0.001) higher erythrocyte surface sialic acid concentrations than Ndama calves. Ndama adults and calves had significantly (P less than 0.001) higher erythrocyte surface sialic acid concentrations than Zebu adults. There were no significant differences between the packed cell volume (PCV), haemoglobin (Hb) concentrations and total leukocyte counts (WBC) of these breeds. The finding of much higher erythrocyte surface sialic acid concentrations (about 7-fold) in the Ndama than in the Zebu is discussed in relation to the induction of anaemia by trypanosome sialidase in both breeds and to how a relative trypano-tolerance may occur in the Ndama.

Modulation of the calcium pump of the kidney and testes of rats infected with Trypanosoma congolense.

The activity of the CaMgATPase (Ca-pump) of the kidney and testes of Wistar rats infected with Trypanosoma congolense was studied during the course of infection. The activity of the enzyme in both organs was found to decrease with increase in parasitaemia. The transition temperature (Tc) decreased and activation energy (Ea) of the enzyme increased with increase in parasitaemia. The relevance of the Ca-pump in the pathogenesis of trypanosomiasis is discussed.

Biochemical differences (O-acetyl and glycolyl groups) in erythrocyte surface sialic acids of trypanotolerant N'dama and trypanosusceptible Zebu cattle.

Differences in the distribution and concentration of O-acetyl and glycolyl groups in erythrocyte sialic acids of trypanotolerant N'dama and trypanosusceptible Zebu cattle were investigated. Erythrocyte surface sialic acid concentrations were 25.4 +/- 5.5 mg per dl and 5.9 +/- 0.97 mg per dl in N'dama and Zebu animals, respectively. In N'damas, O-acetyl and glycolyl groups were present in concentrations of 16.4 +/- 4.3 mg per dl and 12.8 +/- 2.9 mg per dl, respectively, whereas the corresponding values in Zebus were 2.8 +/- 5.0 mg per dl and 7.6 +/- 1.7 mg per dl, respectively. The differences between N'dama and Zebu cattle in surface sialic acids and in O-acetyl and glycolyl groups were significant (P < 0.01 to < 0.001). N'dama erythrocyte sialic acids had more O-acetyl than glycolyl groups while those of Zebus had less O-acetyl than glycolyl groups. These findings may be relevant to the trypanotolerance of N'dama cattle.

Electrophoresis of bovine erythrocyte sialic acids: existence of additional band in trypanotolerant Ndama cattle.

Mild acid-hydrolysis of erythrocyte surface sialic acids of the trypanotolerant Ndama and the trypanosusceptible White/Fulani Zebu breeds of cattle was performed. The cleaved sialic acids from the two breeds of cattle were simultaneously subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE), along with commercial standard N-acetylneuraminic acid (MW 309.28), blank gel and plasma proteins. The cleaved sialic acids migrated in the globulin fractions, as shown by the plasma protein electrophoresis. While the Ndama and the Zebu erythrocytes had one migrating band each of which coincided with the standard N-acetylneuraminic acid, the Ndama had another trailing band of sialic acid, of an estimated molecular weight of 30 kDa, which may account for the higher erythrocyte sialic acid concentrations of the Ndama. This additional band was absent in the Zebu. All these bands were readily reproducible.