Toxoplasma co-opts host cells it does not invade.
Like many intracellular microbes, the protozoan parasite Toxoplasma gondii injects effector proteins into cells it invades. One group of these effector proteins is injected from specialized organelles called the rhoptries, which have previously been described to discharge their contents only during successful invasion of a host cell. In this report, using several reporter systems, we show that in vitro the parasite injects rhoptry proteins into cells it does not productively invade and that the rhoptry effector proteins can manipulate the uninfected cell in a similar manner to infected cells. In addition, as one of the reporter systems uses a rhoptry:Cre recombinase fusion protein, we show that in Cre-reporter mice infected with an encysting Toxoplasma-Cre strain, uninfected-injected cells, which could be derived from aborted invasion or cell-intrinsic killing after invasion, are actually more common than infected-injected cells, especially in the mouse brain, where Toxoplasma encysts and persists. This phenomenon has important implications for how Toxoplasma globally affects its host and opens a new avenue for how other intracellular microbes may similarly manipulate the host environment at large.
Department of Medicine (Infectious Disease), Stanford University School of Medicine, Stanford, California, United States of America.
Anita A
AA
Koshy
Hans K
HK
Dietrich
David A
DA
Christian
Jason H
JH
Melehani
Anjali J
AJ
Shastri
Christopher A
CA
Hunter
John C
JC
Boothroyd
D000818:Animals; D002460:Cell Line; D005347:Fibroblasts / Q000469:parasitology*; D006790:Host-Parasite Interactions; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*; D050800:STAT6 Transcription Factor / Q000378:metabolism; D014122:Toxoplasma / Q000378:metabolism* / Q000472:pathogenicity*
D015800:Protozoan Proteins; D050800:STAT6 Transcription Factor; D011505:Protein-Tyrosine Kinases; C552524:Rop16 protein, Toxoplasma gondii