Serum Total and Lipid-Bound Sialic Acid Concentrations in Sheep with Natural Babesiosis

Deger Y., H. Mert, S. Dede, F. Yur, N. Mert: Serum Total and Lipid-Bound Sialic Acid Concentrations in Sheep with Natural Babesiosis. Acta Vet. Brno 2007, 76: 379-382. The aim of this study was to determine the serum concentrations of total and lipid-bound sialic acid in sheep naturally infected with Babesia ovis before and after treatment. Thirty diseased sheep and ten control animals were used. Babesia infection was confi rmed with Giemsa’s staining of blood smears. Compared to the control animals (1.351 ± 0.100 mmol l-1; 0.385 ± 0.001 mmol l-1), a marked increase of serum total and lipid bound sialic acid concentrations (1.929 ± 0.101 mmol l-1; 0.479 ± 0.004 mmol l-1, respectively) was obtained in infected sheep (p < 0.05). One week after treatment, serum total and lipid bound sialic acid concentrations signifi cantly decreased (1.554 ± 0.005 mmol l-1; 0.411 ± 0.02 mmol l-1, respectively) (p < 0.05). Despite this decline, total and lipid bound sialic acid concentrations of treated animals were still signifi cantly increased in sera compared to the control animals (p < 0.05). When the infected animals were treated with an antiparasitic drug (diminazene aceturate), the serum total and lipid bound sialic acid levels had a tendency to decrease to the normal ranges. It can be concluded that Babesia ovis infection induced marked and persistent elevations of serum total and lipid-bound sialic acid concentrations, suggesting that these indicators would indirectly promote the invasion and presence of the parasite in the host. Sheep, Babesia ovis, sialic acids Sialic acids are nine-carbon monosaccharides that link to the terminal galactose, Nacetylgalactosamine, or to other sialic acids in carbohydrate chains of glycoproteins or glycolipids (Corfield and Schauer 1982). Sialic acids usually occupy exposed terminal positions on the oligosaccharide chains of glycoconjugates and frequently serve as ligands for receptors such as selectins and siglecs, which mediate a variety of cell-cell adhesion processes in the infl ammation and in the immune response (Kelm and Schauer 1997; Malykhy et al. 2001). Babesia species are protozoan parasites that develop in the erythrocytes of vertebrate hosts and are transmitted transovarially and transstadially by ixodid ticks (Urquhart et al. 1996; Friedhoff 1988). The severity of the disease caused by these parasites, namely babesiosis, is related to the vertebrate host and protozoan species (Urquhart et al. 1996). Ovine babesiosis is the most important haemoparasitic tick-borne disease of small ruminants caused by Babesia ovis, Babesia motasi and Babesia crassa. These parasites are widespread in tropical and subtropical areas of the world (Uilenberg 2001). Babesia ovis is highly pathogenic especially in sheep, and causes severe infections that are charecterised by fever, anaemia, icterus and haemoglobinuria (Almeria et al. 2001). Sialic acids are present in normal human and animal serum. It has been demonstrated that sialic acid concentrations are elevated in patients suffering from various diseases (Schutter et al. 1992; Wongkham et al. 2003). However, the effect of Babesia ovis infection on serum total and lipid-bound sialic acid content in sheep has not been reported previously. ACTA VET. BRNO 2007, 76: 379-382; doi:10.2754/avb200776030379 Address for correspondence: Dr. Yeter Değer Department of Biochemistry, Faculty of Veterinary Medicine, Yuzuncu Yıl University Van 65080, Turkey Tel: +90 432 225 1128 Fax: +90 432 225 1127 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm Therefore, the aim of the present study was to examine if there is any relationship between babesiosis and the serum total and lipid-bound sialic acid concentrations. Materials and Methods Forty Akkaraman sheep with a body mass of 25 30, at the age of 4 5 years and localized in different regions of Van between June and August of 2005 were used as subjects for this study. Thirty sheep were infected naturally with Babesia ovis and ten control animals were clinically healthy. All the cattle included in this study submitted to clinical and parasitological examinations. Treatment of thirty infected animals was conducted with diminazene aceturate (Berenil®) 7% solution) once at a dose of 3.5 mg/kg, intramuscularly. Blood samples of all animals were taken into plain and EDTA containing vacutainer tubes from the jugular vein. Samples were fi rstly taken at the onset of the disease during the disease season of babesiosis (June August), then one week following the treatment of the diseased animal. At this time, the treated animals did not show any clinical signs of babesiosis. Serum samples were obtained after centrifugation at 1700 g for 15 minutes at room temperature, aliquoted and stored at -20 °C until used. Serum total sialic acid concentration was determined by a method previously described by Sydow (1988). Lipid bound sialic acid concentration was determined by the method described by Katopodis et al. (1982). The amount of total and lipid bound sialic acid were determined by use of a standard curve developed from a standard sample of n-acetyl neuraminic acid. EDTA-blood was used to prepare thin blood smears. Blood smears were fi xed in methanol, stained with Giemsa and examined for the presence of blood protozoa. The results were expressed as means ± standard deviation. Duncan’s test was used for statistical analysis, setting p < 0.05 to establish statistically signifi cant differences.