Plasma protein loss in lambs during a mixed infection of Trichostrongylus colubriformis and Teladorsagia circumcincta - a consequence of the immune response?
A.L. VAUGHAN, A.W. GREER, R.W. MCANULTY AND A.R. SYKES
Proceedings of the New Zealand Society of Animal Production 66: 83-87.
The effect of corticosteroid-induced immuno-suppression on the plasma protein loss of lambs infected with gastrointestinal nematode parasites was investigated. Eight parasite naïve lambs received either a mixed infection of Teladorsagia circumcincta and Trichostrongylus colubriformis (group IF) or received the same infection while concurrently immuno-suppressed with the corticosteroid methylprednisolone acetate (group IS). Concentrations of nematode eggs in the faeces of lambs increased to 1,500 epg in IF and 4,000 epg in IS by day 42, indicating successful immuno-suppression. Infection reduced plasma albumin concentration compared with pre-infection levels by 19% in IF animals (p<0.05), but only 7% (ns) in IS animals. Plasma loss (ml day-1) into the gastrointestinal tract was estimated during two seven day periods through the appearance of intravenously infused 51Cr in the faeces. Protein loss into the gastrointestinal tract (g d-1) was calculated by multiplying the plasma loss (ml d-1) by the total protein concentration in the plasma (g l-1). Plasma protein losses at day 35 were increased by 310% in IF and by 258% in IS relative to pre-infection levels, and were not affected by immuno-suppression (p>0.05). These results suggest the leakage of plasma proteins into the alimentary tract are a consequence of intestinal pathology caused by the parasite, rather than detrimental components of the immune reaction. It is hypothesised the ability of IS animals to maintain plasma albumin is the result of a greater ability to replace leaked proteins as a consequence of the net catabolic actions of corticosteroids.
Keywords: NZSAPAB; Nematoda; immuno-suppression; plasma protein; sheep.
Last Updated 2/07/2006