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Eimeria acervulina infection elevates plasma and muscle 3-methylhistidine levels in chickens
1Parasite Biology and Epidemiology Laboratory, Livestock and Poultry Sciences Institute, United States Department of Agriculture, Beltsville Agricultural Research Center, Maryland 20750, USA.
Abstract:
To assess muscle breakdown during avian coccidiosis, the level of the nonmetabolizable amino acid 3-methylhistidine (3MH) was determined in muscle, plasma and excreta from chickens infected with Eimeria acervulina. The changes in 3MH levels during infection were assessed at 1-29 days postinoculation (DPI) in animals given 5 x 10(5) oocysts per bird. The effect of levels of parasitism were evaluated at 8 DPI in birds receiving 5 x 10(3), 5 x 10(4), 5 x 10(5) or 1 x 10(6) oocysts each. The 3MH levels of plasma, muscle, and excreta samples were determined by high-pressure liquid chromatography after derivatization with fluorescamine. Weight gains, breast muscle weight, eviscerated weight, plasma carotenoid levels, dry weight of muscle, and gross lesion scores were also determined. Infected birds had significantly elevated plasma and muscle 3MH at 4 and 8 DPI following a single dose of E. acervulina. The increase in 3MH levels had an inverse relationship with the time course of weight gain and plasma carotenoid levels. Plasma and muscle 3MH levels returned to control values by 15 DPI and remained unchanged from control values through the remainder of the experiment (29 DPI). Breast weight was decreased in infected birds, but the ratio of breast weight to eviscerated body weight was unchanged. Excretion of 3MH decreased relative to controls at 4 and 8 DPI and returned to control levels on 15 DPI. The plasma and muscle levels of 3MH were related to severity of infection; however, levels of excreted 3MH were not. The results suggested that muscle breakdown, as assessed by plasma and muscle levels of 3MH, increased during the acute stage of E. acervulina infection. The underlying causes for this muscle breakdown was unclear but could involve a physiological response to anorexia and decreased food intake during the acute phase of infection. Levels of excreted 3MH did not increase during infection and this may be the result of decreased excreta output during infection. Plasma and muscle levels of 3MH were correlated with severity of E. acervulina infections but may not be as sensitive an indicator of infection as plasma carotenoid levels or other physiological parameters.
Insights
Avian coccidiosis from Eimeria acervulina increases muscle breakdown, indicated by elevated 3-methylhistidine (3MH) in chicken plasma and muscle during acute infection. These levels normalize by 15 days post-inoculation.
Area of Science:
- Veterinary Parasitology
- Animal Science
- Biochemistry
Background:
- Avian coccidiosis, caused by Eimeria species, significantly impacts poultry health and economics.
- Muscle breakdown is a potential consequence of parasitic infections, but direct biochemical markers are needed.
- 3-methylhistidine (3MH) is a non-metabolizable amino acid indicative of skeletal muscle protein degradation.
Purpose of the Study:
- To quantify muscle breakdown during Eimeria acervulina infection in chickens using 3MH levels.
- To correlate 3MH levels with infection severity, weight gain, and other physiological parameters.
- To assess the temporal dynamics of muscle breakdown markers throughout the infection course.
Main Methods:
- Chickens were infected with varying doses of Eimeria acervulina oocysts.
- Muscle, plasma, and excreta samples were analyzed for 3MH using high-pressure liquid chromatography.
- Measurements included weight gains, muscle weights, plasma carotenoids, and lesion scores.
Main Results:
- Plasma and muscle 3MH levels significantly increased at 4 and 8 days post-inoculation (DPI) in infected chickens.
- Elevated 3MH showed an inverse relationship with weight gain and plasma carotenoid levels.
- 3MH levels returned to baseline by 15 DPI, while excreted 3MH decreased during acute infection.
Conclusions:
- Eimeria acervulina infection induces muscle breakdown during its acute phase, as evidenced by increased plasma and muscle 3MH.
- The observed muscle breakdown may be linked to anorexia and reduced feed intake.
- Plasma and muscle 3MH levels correlate with infection severity but may be less sensitive than other physiological indicators like plasma carotenoids.