Depicting "arms race" of Rhipicephalus microplus and its host on a single frame platform

Abstract

To improve our knowledge on host-parasite interaction, the study was undertaken on Rhipicephalus microplus infestation in cross breed cattle. This tick, being a voracious blood sucker, remains attached to the skin for prolonged period and inoculates saliva during blood feeding. Biomolecules present in the saliva have detrimental effects on host system. The present study deals with the effects of R. microplus in artificially infected nine months old cattle for a period of 21 days. There was physiological alteration during tick infestation in terms of body temperature, pulse, and respiration rate. There was drop in haemoglobin gram percentage, platelet count, total red and white blood cell count. Thrombocytopenia in infested animals was suggestive of iron deficient anaemia after artificial infestation. R. microplus infestation was found to induce stress in experimental animals. Our study on peripheral blood gene expression was suggestive of Th2 polarization since there was increased IL-4 response. Increased IL-6 response indicated skin damage due to R. microplus infestation and we further correlate eosinophilia with up-regulation of IL-6 and IL-8 responses. Increased IL-10 response and decreased IFN-γ response were suggestive of immunosuppressive and anti-inflammatory properties of tick saliva.

Keywords: Rhipicephalus microplus; Blood profile; Cytokines; Host-parasite interaction; Interleukin; Physiological parameters.

Fig. 1

Effect of tick infestation on erythrocytic parameters; (a) Hb concentration, (b) RBC concentration, (c) PCV, (d) MCV, (e) MCH, and (f) MCHC. Parameters were evaluated before the tick infestation (0-Day, 0D) and after infestation (1 day to 21 day). Values are presented as Mean ± SEM. Statistical significance was calculated by one-way ANOVA followed by Dunnett's post-test. Values with asterisk indicate significant difference as compared to control (0-Day value), *denotes p ≤ 0.05, **denotes p ≤ 0.01, ***denotes p ≤ 0.001, ****denotes p ≤ 0.0001. Hb indicates haemoglobin concentration, RBC indicates red blood cell concentration, PCV indicates packed cell volume, MCV indicates mean corpuscular volume, MCH indicates mean corpuscular haemoglobin, and MCHC indicates mean corpuscular haemoglobin concentration. R. microplus infestation induced a decrease in Hb, RBC, PCV, and MCHC values, an increase in MCV values, whereas MCH values were unchanged

Fig. 2

Effect of tick infestation on leukocytic parameters; (a) WBC concentration, (b) Basophil %, (c) Eosinophil %, (d) Monocyte %, (e) Neutrophil %, and (f) Lymphocyte %. Parameters were evaluated before the tick infestation (0-Day, 0D) and after infestation (1 day to 21 day). Values are presented as Mean ± SEM. Statistical significance was calculated by one-way ANOVA followed by Dunnett's post-test. Values with asterisk indicate significant difference as compared to control (0-Day value), *denotes p ≤ 0.05, **denotes p ≤ 0.01, ***denotes p ≤ 0.001, ****denotes p ≤ 0.0001. WBC indicates white blood cell concentration. R. microplus infestation induced a decrease in WBC, and Neutrophil %, and an increase in Eosinophil %, Basophil %, Monocyte % and Lymphocyte %

Fig. 3

Effect of tick infestation on platelet concentration. Concentration was evaluated before the tick infestation (0-Day, 0D) and after infestation (1 day to 21 day). Values are presented as Mean ± SEM. Statistical significance was calculated by one-way ANOVA followed by Dunnett's post-test. Values with asterisk indicate significant difference as compared to control (0-Day value), ****denotes p ≤ 0.0001. R. microplus infestation induced a decrease in platelet concentration

Fig. 4

Effect of tick infestation on antioxidant profiles and oxidative stress indicator. Parameters were evaluated before the tick infestation (0-Day, 0D) and after infestation (1 day to 21 day). Values are presented as Mean ± SEM. Statistical significance was calculated by one-way ANOVA followed by Dunnett's post-test. Values with asterisk indicate significant difference as compared to control (0-Day value), *denotes p ≤ 0.05, **denotes p ≤ 0.01, ***denotes p ≤ 0.001, ****denotes p ≤ 0.0001. MDA indicates malondialdehyde, TAA indicates Total antioxidant activity, GSH indicates glutathione-S-transferase and SOD indicates superoxide dismutase. R. microplus infestation induced a decrease in TAA, catalase, GSH, and SOD, and an increase in MDA

Fig. 5

Effect of tick infestation on relative expression of cytokine genes. Expression of (a) IL-1β, (b) IL-12, (c) IL-8, (d) IL-4, (e) IL-10, (f) FoxP3, (g) IL-6, (h) CD25, (i) IL-2, (j) CXCL10, (k) IFNγ, and (l) TNFα was studied. Expression was assessed before the tick infestation (0-Day) and after infestation (1 day to 21 day). 0-day expression was considered as control. Fold change in transcript upon tick-infestation is presented with respect to control. The values and error bars represent average and standard deviations of three independent sets of experiments. Statistical significance was calculated by one-way ANOVA followed by Dunnett's post-test. Values with asterisk indicate significant difference as compared to control (0-Day value), *denotes p ≤ 0.05, **denotes p ≤ 0.01, ***denotes p ≤ 0.001, ****denotes p ≤ 0.0001. IL-1β, IL-12, IL-8, IL-4, IL-10, FoxP3, IL-6, and CD25 were upregulated, IL-2 was unchanged, and the rest of the genes were downregulated