The haematological, proinflammatory cytokines and IgG changes during an ovine experimental theileriosis

Abstract

Malignant ovine theileriosis is caused by Theileria lestoquardi , which is highly pathogenic in sheep. Theileriosis involves different organs in ruminants. Little is known about the role of proinflammatory cytokines in the pathogenesis of T. lestoquardi infection. The aim of this study was to measure concentration changes of proinflammatory cytokines and immunoglobulin G (IgG) during an ovine experimental theileriosis and correlate it with clinical and haematological parameters. During an experimental study, seven healthy Baluchi sheep (four females and three males) about 6–8 months old were infected with T. lestoquardi by feeding of infected unfed ticks on the sheep’s ears. The infected sheep were clinically examined during the study and blood samples were collected on days 0, 2, 5, 7, 10, 12, 14, 17 and 21. The haematological parameters were analysed by an automatic veterinary haematology cell counter and the inflammatory cytokines interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and IgG were measured by enzyme-linked immunosorbent assay. All infected sheep had temperatures above 40 °C on days 3–4 post infection (PI). The maximum temperature was noted on day 7, and it remained high until day 21. The parasitaemia of T. lestoquardi infection increased from 0.01% (day 7 PI) to 3.3% (day 21 PI). The mean white blood cell (WBC), red blood cell (RBC), lymphocyte, neutrophil and platelet values slightly increased on day 2 PI and decreased by day 17 and day 21 PI. The percentage parasitaemia and fever had a negative correlation with the numbers of WBCs, RBCs, lymphocytes, neutrophils and platelets. The serum concentration of IL-6, TNF-α and IFN-γ cytokines increased and peaked on day 12 and thereafter decreased to levels lower than 0. Out of all tested cytokines, the concentration of IL-6 was significantly higher, as early as day 2 PI. No significant changes were observed for the IgG levels during the course of disease. A significant and strong correlation was observed between IL-6, TNF-α and IFN-γ values and a moderate correlation between IL-6 and the numbers of lymphocytes in the present study. A strong correlation was determined between the percentage parasitaemia and haematological parameters in T. lestoquardi -infected sheep. In addition, preliminary results indicate that the measurement of the serum concentrations of IL-6 in combination with haematological parameters could be considered a good marker to estimate the pathogenicity of T. lestoquardi strain.

Role of cytokines in the clinical manifestation of exophthalmia in newborn calves with tropical theileriosis

“…Our findings are in agreement with the recent observations of elevated serum concentration of IL‐6, TNF‐α and IFN‐γ cytokines in experimental ovine theileriosis 13 . Interferon‐γ mainly produced from T annulata stimulated T cells and not from infected cells.…”

Ovine Theileriosis: Clinical, Pathological and Molecular Investigations

“…A permanent tick blood sucking causing chronic blood loss (Minnat and Abdulwadood, 2012). These results agreed with the results recorded by Al-Fetly (2012), Razavi et al (2015) and Sohail et al (2018).…”

“…Moreover, Weiss and Wardrop (2010) reported that the eosinopenia and pancytopenia in Theileria infected animals may be due to parasitic toxins or different causes of necrosis, fibrosis, or suppression in bone marrow. These results were in agreement with Çöl and Uslu, (2006), Yaghfoori et al (2017), Minnat and Abdulwadood (2012) and Khan et al (2017) while leukocytosis in Theileria infected sheep were demonstrated in some studies that results due to stage of infection and proliferation of lymphocytes in the lymphoid organs as a defensive response to parasitic infection (Al-Fetly, 2012;Sohail et al, 2018;Razmi et al, 2019).…”

“…Results of erythrogram revealed significant macrocytic hypochromic anemia in the infected groups compared with Theileria negative group. The hemolytic anemia occurs due to presence of parasites inside the RBCs causes hemolysis result from erythrocytic fragility (Mahmoud et al, 2019) and stimulation of erythrophagocytosis in reticuloendothelial system (Razmi et al, 2019). A permanent tick blood sucking causing chronic blood loss (Minnat and Abdulwadood, 2012).…”

“…The leukogram of infected groups showed significant leukopenia due to neutropenia, lymphopenia, monocytopenia and eosinopenia, compared with the Theileria negative group. This leukopenia may be explained as a results of destruction of infected lymphocytes due to presence of schizogony of parasite inside them (Mahmoud et al, 2019) while the decrease of other cells may be due to the suppression of bone marrow and leukopoiesis as a result of parasitic products and increase TNF-α production (Razmi et al, 2019). Moreover, Weiss and Wardrop (2010) reported that the eosinopenia and pancytopenia in Theileria infected animals may be due to parasitic toxins or different causes of necrosis, fibrosis, or suppression in bone marrow.…”