title: Mixed inoculations of a microsporidian parasite with horizontal and vertical infections.
abstract: Mixed infections, where more than one parasite genotype is present in a single host, have been suggested to be an important factor in host-parasite interactions. As the host represents a limited resource, co-infecting parasite genotypes are expected to be under resource competition. Competition will not only modify the survival of the co-infecting genotypes, but is also likely to affect total within-host parasite growth as well as host survival and reproduction. We measured parasite infectivity and spore production of seven isolates of Octosporea bayeri (Microsporidia) and their effect on the reproduction and longevity of its host Daphnia magna (Cladocera), after single- or double-isolate inoculations through vertical and horizontal transmission. Double-isolate inoculations increased parasite infectivity and total spore production in horizontal infections, but had no significant effect on host reproduction or longevity. The increase in spore production in double-isolate inoculations was not found when infections occurred vertically. Our results suggest that, depending on the way the infection was acquired, within-host reproduction can increase as a result of parasite genetic diversity, without necessarily affecting the host's fitness. Whether this challenges the current views of virulence evolution depends on the definitions used.
authors.affiliation: Département de Biologie, Unité d'Ecologie and Evolution, Université de Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland. dita.vizoso@uibk.ac.at
authors.forename: Dita B
authors.initials: DB
authors.lastname: Vizoso
authors.forename: Dieter
authors.initials: D
authors.lastname: Ebert
mesh_terms: D000818:Animals; D003621:Daphnia / Q000469:parasitology* / Q000502:physiology; D014644:Genetic Variation; D005838:Genotype; D006790:Host-Parasite Interactions; D016814:Microsporidia / Q000235:genetics / Q000472:pathogenicity*; D012098:Reproduction
references.citation: J Evol Biol. 2005 Jul;18(4):911-21
references.pmid: 16033563
references.citation: Evolution. 2002 Mar;56(3):518-26
references.pmid: 11989682
references.citation: Microbes Infect. 2001 Apr;3(5):381-8
references.pmid: 11369275
references.citation: Evolution. 2003 Jul;57(7):1543-51
references.pmid: 12940359
references.citation: Proc Biol Sci. 2002 Jul 7;269(1498):1317-23
references.pmid: 12079653
references.citation: J Invertebr Pathol. 2002 Oct;81(2):103-13
references.pmid: 12445794
references.citation: Trends Microbiol. 2002 Sep;10(9):401-5
references.pmid: 12217504
references.citation: Parasitology. 1997 Sep;115 ( Pt 3):317-24
references.pmid: 9300470
references.citation: Q Rev Biol. 1996 Mar;71(1):37-78
references.pmid: 8919665
references.citation: J Theor Biol. 1989 Jan 23;136(2):199-207
references.pmid: 2779267
references.citation: J Theor Biol. 1983 Feb 7;100(3):411-26
references.pmid: 6834864
references.citation: Science. 1994 Aug 19;265(5175):1084-6
references.pmid: 17832903
references.citation: Proc Biol Sci. 2003 Jan 22;270(1511):189-93
references.pmid: 12590759
references.citation: Proc Natl Acad Sci U S A. 1996 Feb 6;93(3):985-9
references.pmid: 8577773
references.citation: Parasitol Today. 1999 Dec;15(12):474-5
references.pmid: 10557145
references.citation: Evolution. 2001 May;55(5):1056-62
references.pmid: 11430642
references.citation: Proc Natl Acad Sci U S A. 1994 May 24;91(11):4821-4
references.pmid: 8197141
references.citation: Evolution. 1991 Jun;45(4):875-882
references.pmid: 28564051
references.citation: Parasitology. 2002 Jan;124(Pt 1):31-8
references.pmid: 11811801
references.citation: Nature. 1999 Apr 1;398(6726):441-3
references.pmid: 10201376
references.citation: Oecologia. 2000 Feb;122(2):200-209
references.pmid: 28308373
references.citation: Proc Biol Sci. 1997 Jul 22;264(1384):985-91
references.pmid: 9263465
references.citation: Am Nat. 2004 Apr;163(4):E40-63
references.pmid: 15122509
references.citation: Evolution. 1994 Oct;48(5):1423-1437
references.pmid: 28568406
references.citation: Parasitology. 2005 May;130(Pt 5):501-9
references.pmid: 15991493
references.citation: Proc Biol Sci. 1995 Aug 22;261(1361):209-15
references.pmid: 7568274
references.citation: Proc Biol Sci. 1992 Dec 22;250(1329):249-56
references.pmid: 1362993
references.citation: Parasitology. 2004 Jan;128(Pt 1):31-8
references.pmid: 15002901
references.citation: Evolution. 1991 Jun;45(4):1036-1046
references.pmid: 28564047
references.citation: Proc Biol Sci. 1992 Dec 22;250(1329):195-7
references.pmid: 1362989
references.citation: Proc Biol Sci. 2002 Feb 22;269(1489):397-402
references.pmid: 11886628
references.citation: Proc Biol Sci. 1997 Jun 22;264(1383):927-35
references.pmid: 9225482
references.citation: Trends Microbiol. 1994 Mar;2(3):73-6
references.pmid: 8156274
references.citation: Science. 1993 Mar 5;259(5100):1442-5
references.pmid: 17801279
references.citation: Science. 2002 Jan 18;295(5554):485-8
references.pmid: 11799241
references.citation: Science. 2001 May 11;292(5519):1099-102
references.pmid: 11352063