Outcome of within-host competition demonstrates that parasite virulence doesn't equal success in a myxozoan model system

Publication date: Available online 18 March 2019Source: International Journal for Parasitology: Parasites and WildlifeAuthor(s): C.N. Hurst, J.D. Alexander, B.P. Dolan, J. Luo, J.L. BartholomewAbstractWithin-host competition can affect outcomes of infections when parasites occupy the same niche. We investigated within-host competition and infection outcomes in Chinook salmon exposed to two genotypes of Ceratonova shasta (myxozoan parasite). We assessed i) virulence (host mortality, median days to death), ii) within-host competition (abundance in host), and iii) success (spore production, proportion of myxospore-producing hosts) following concurrent and sequential exposures to single or mixed-genotype treatments. In single treatments, genotype-I replicated faster, and caused higher and earlier host mortality (higher virulence) but genotype-II produced more myxospores (higher success). In mixed treatments, costs of competition were observed for both genotypes evidenced by reduced replication or myxospore production following concurrent exposures, but only the less-virulent genotype suffered costs of competition when hosts were exposed to genotypes sequentially. To understand potential host effects on competition outcomes, we characterized systemic (spleen) and local (intestine) cytokine and immunoglobulin expression in single and mixed infections. We observed delayed systemic and immunosuppressive responses to the virulent genotype (I), rapid, localized and non-suppressive resp...
Source: International Journal for Parasitology: Parasites and Wildlife - Category: Parasitology Source Type: research