Within-host competitive interactions as a mechanism for the maintenance of parasite diversity

• Published in: Philosophical transactions of the Royal Society of London. Series B. Biological sciences Vol. 370; no. 1675; p. 20140301
• Main Author: Bashey, Farrah
• Format: Journal Article
• Language: English
• Published: England The Royal Society 19.08.2015
• Subjects: Animals; Bacteriocins; Coexistence; Genetic Variation; G×g Interactions; Host-Parasite Interactions - genetics; Humans; Models, Biological; Parasite Diversity; Parasites - genetics; Parasites - pathogenicity; Parasitic Diseases - genetics; Parasitic Diseases - parasitology; Public Goods; Review; Within-Host Competition; bacteriocins; parasite diversity; within-host competition; coexistence; public goods; G×G interactions
• ISSN: 0962-8436; 1471-2970
• DOI: 10.1098/rstb.2014.0301

Variation among parasite strains can affect the progression of disease or the effectiveness of treatment. What maintains parasite diversity? Here I argue that competition among parasites within the host is a major cause of variation among parasites. The competitive environment within the host can vary depending on the parasite genotypes present. For example, parasite strategies that target specific competitors, such as bacteriocins, are dependent on the presence and susceptibility of those competitors for success. Accordingly, which parasite traits are favoured by within-host selection can vary from host to host. Given the fluctuating fitness landscape across hosts, genotype by genotype (G×G) interactions among parasites should be prevalent. Moreover, selection should vary in a frequency-dependent manner, as attacking genotypes select for resistance and genotypes producing public goods select for cheaters. I review competitive coexistence theory with regard to parasites and highlight a few key examples where within-host competition promotes diversity. Finally, I discuss how within-host competition affects host health and our ability to successfully treat infectious diseases.