Recent Expansion of Toxoplasma through Enhanced Oral Transmission

• Published in: Science (American Association for the Advancement of Science) Vol. 299; no. 5605; pp. 414 - 416
• Main Authors: Su, C., Evans, D., Cole, R. H., Kissinger, J. C., Ajioka, J. W., Sibley, L. D.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 17-01-2003
• Subjects: Animals; Biological and medical sciences; Biological evolution; Cats; Cysts; DNA, Ribosomal - genetics; DNA, Ribosomal Spacer - genetics; Food Parasitology; Foodborne illnesses; Fundamental and applied biological sciences. Psychology; General aspects and techniques; Genes, Protozoan; Genetic crosses; Genetic mutation; Genetics of eukaryotes. Biological and molecular evolution; Infections; Intermediate hosts; Introns; Life Cycle Stages; Mice; Molecular Sequence Data; Mouth; Mutation; Parasitism; Phylogeny; Polymorphism, Genetic; Polymorphism, Single Nucleotide; Protozoa; Recombination, Genetic; Reproduction; Selection, Genetic; Taxa; Toxoplasma; Toxoplasma - genetics; Toxoplasma - pathogenicity; Toxoplasma - physiology; Toxoplasmosis - parasitology; Toxoplasmosis - transmission; Toxoplasmosis, Animal - parasitology; Toxoplasmosis, Animal - transmission; Virulence; Toxoplasma; Protozoa; Oral cavity; Host parasite relation; Apicomplexa; Genetic variability; Biological evolution; Infectivity; Parasitism; Polymorphism
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1078035

The global predominance of three clonal Toxoplasma gondii lineages suggests that they are endowed with an exceptional trait responsible for their current parasitism of nearly all warm-blooded vertebrates. Genetic polymorphism analyses indicate that these clonal lineages emerged within the last 10,000 years after a single genetic cross. Comparison with ancient strains (~1 million years) suggests that the success of the clonal lineages resulted from the concurrent acquisition of direct oral infectivity. This key adaptation circumvented sexual recombination, simultaneously promoting transmission through successive hosts, hence leading to clonal expansion. Thus, changes in complex life cycles can occur rapidly and can profoundly influence pathogenicity.