Rodent malaria parasites suffer from the presence of conspecific clones in three-clone Plasmodium chabaudi infections

J. C. DE ROODE a1c1, A. F. READ a1, B. H. K. CHAN a1 and M. J. MACKINNON a1
a1 Institute of Cell, Animal and Population Biology, University of Edinburgh, Ashworth Laboratories, King's Buildings, West Mains Road, Edinburgh EH9 3JT, Scotland, UK

Article author query
de roode j   [PubMed][Google Scholar] 
read a   [PubMed][Google Scholar] 
chan b   [PubMed][Google Scholar] 
mackinnon m   [PubMed][Google Scholar] 


We studied infection dynamics of Plasmodium chabaudi in mice infected with 3 genetically distinct clones – 1 less virulent than the other 2 – either on their own or in mixtures. During the acute phase of infection, total numbers of asexual parasites in mixed-clone infections were equal to those produced by the 3 clones alone, suggesting strong in-host competition among clones. During the chronic phase of the infection, mixed-clone infections produced more asexual parasites than single-clone infections, suggesting lower levels of competition than during the acute phase, and indicating that a genetically diverse infection is harder to control by the host immune system. Transmission potential over the whole course of infection was lower from mixed-clone infections than from the average of the 3 single-clone infections. These results suggest that in-host competition reduces both growth rate and probability of transmission for individual parasite clones.

(Received October 21 2002)
(Revised March 28 2003)
(Accepted May 31 2003)

Key Words: malaria; Plasmodium chabaudi; virulence; evolution; competition; mixed infections.

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