Cellular Inflammatory Response of Rainbow Trout to the Protozoan Parasite that Causes Proliferative Kidney Disease

Elizabeth MacConnell, Charlie E. Smith, Ronald Hedrick, C. A. Speer

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The cellular inflammatory response of rainbow trout Oncorhynchus mykiss (formerly Salmo gairdneri) to the myxozoan parasite PKX that causes proliferative kidney disease was investigated. The response was studied from 3 to 20 weeks after the fish were injected with infected kidney homogenate. Kidney samples were examined by light and electron microscopy. In contrast to most myxosporeans, PKX provoked a severe host response. Parasites were found in peritubular capillaries and sinusoids 3 weeks postinjection. The initial response to PKX was hemopoietic hyperplasia followed by a marked granulomatous nephritis that was resolved by termination of the study at 20 weeks postinjection. The macrophage was the predominant cell type involved in the inflammatory response to PKX. We presume that the macrophage effectively interrupts the development of PKX and eliminates the parasite from the host.

Original languageEnglish (US)
Pages (from-to)108-118
Number of pages11
JournalJournal of Aquatic Animal Health
Issue number2
StatePublished - Jan 1 1989


ASJC Scopus subject areas

  • Aquatic Science

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