Changing patterns of acute phase proteins and inflammatory mediators in experimental caprine coccidiosis

Abstract

This experiment was conducted to assess the changing patterns and relative values of acute phase proteins and inflammatory cytokines in experimental caprine coccidiosis. Eighteen newborn kids were allocated to 3 equal groups. Two groups, A and B, were inoculated with a single dose of 1×10(3) and1×10(5) sporulated oocysts of Eimeria arloingi, respectively. The third group, C, received distilled water as the control. Blood samples were collected from the jugular vein of each kid in both groups before inoculation and at days 7, 14, 21, 28, 35, and 42 post-inoculation (PI), and the levels of haptoglobin (Hp), serum amyloid A (SAA), TNF-α, and IFN-γ were measured. For histopathological examinations, 2 kids were selected from each group, euthanized, and necropsied on day 42 PI. Mean Hp concentrations in groups A and B (0.34 and 0.68 g/L) at day 7 PI were 3.2 and 6.3 times higher than the levels before inoculation. The mean SAA concentrations in groups A and B (25.6 and 83.5 µg/ml) at day 7 PI were 4.2 and 13.7 times higher than the levels before inoculation. The magnitude and duration of the Hp and SAA responses correlated well with the inoculation doses and the severity of the clinical signs and diarrhea in kids. These results were consistent with the histopathological features, which showed advanced widespread lesions in group B. In both groups, significant correlations were observed for TNF-α and IFN-γ with SAA and Hp, respectively. In conclusion, Hp and SAA can be useful non-specific diagnostic indicators in caprine coccidiosis.

Keywords: Eimeria arloingi; acute phase protein; caprine coccidiosis; interferon-γ; tumor necrosis factor-α.

Fig. 1

The daily oocyst outputs of groups A and B over the period of whole experiment

Fig. 2

The kinetics of acute phase proteins and inflammatory mediators following experimental infection of goats (kids) with E. arloingi. (A) Haptoglobin (Hp), (B) Serum amyloid A (SAA), (C) TNF-α, and (D) IFN-γ. Results are shown as mean±SEM. 0=before inoculation (♦, Group A; ▪, Group B; ▴, Group C).

Fig. 3

Jejunum of an infected kid (formalin-fixed). Thickening of the jejunal mucosa and the presence of scattered whitish pinhead size (1-2 mm in diameter) nodules (arrows) are seen.

Fig. 4

Jejunum of an infected kid. The endogenous stages of parasites (mature schizonts, microgametocytes, macrogametocytes, and immature oocysts) are observed in the epithelial cells of affected villi. H-E stained. Bar=50 µm.