Lactate dehydrogenase in Toxoplasma gondii controls virulence, bradyzoite differentiation, and chronic infection.
In the asexual stages, Toxoplasma gondii stage converts between acute phase rapidly replicating tachyzoites and chronic phase slowly dividing bradyzoites. Correspondingly, T. gondii differentially expresses two distinct genes and isoforms of the lactate dehydrogenase enzyme, expressing LDH1 exclusively in the tachyzoite stage and LDH2 preferentially in the bradyzoite stage. LDH catalyzes the interconversion of pyruvate and lactate in anaerobic growth conditions and is utilized for energy supply, however, the precise role of LDH1 and LDH2 in parasite biology in the asexual stages is still unclear. Here, we investigated the biological role of LDH1 and LDH2 in the asexual stages, and the vaccine strain potential of deletion mutants lacking LDH1, LDH2, or both genes (Δldh1, Δldh2 and Δldh1/2). Deletion of LDH1 reduced acute parasite virulence, impaired bradyzoite differentiation in vitro, and markedly reduced chronic stage cyst burdens in vivo. In contrast, deletion of LDH2 impaired chronic stage cyst burdens without affecting virulence or bradyzoite differentiation. Deletion of both LDH1 and LDH2 induced a more severe defect in chronic stage cyst burdens. These LDH mutant phenotypes were not associated with any growth defect. Vaccination of mice with a low dose of mutants deleted for LDH elicited effective protective immunity to lethal challenge infection, demonstrating the vaccine potential of LDH deletion mutants. These results suggest that lactate dehydrogenase in T. gondii controls virulence, bradyzoite differentiation, and chronic infection and reveals the potential of LDH mutants as vaccine strains.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.|Clinical laboratory diagnosis, Department of Animal medicine, Faculty of veterinary medicine, Assiut University, Assiut, Egypt.
Abdelbaset E
AE
Abdelbaset
Department of Microbiology & Immunology, The Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America.
Barbara A
BA
Fox
Clinical laboratory diagnosis, Department of Animal medicine, Faculty of veterinary medicine, Assiut University, Assiut, Egypt.
Mohamed H
MH
Karram
Clinical laboratory diagnosis, Department of Animal medicine, Faculty of veterinary medicine, Assiut University, Assiut, Egypt.
Mahmoud R
MR
Abd Ellah
Department of Microbiology & Immunology, The Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America.
David J
DJ
Bzik
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
Makoto
M
Igarashi
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D004926:Escherichia coli; D005260:Female; D055786:Gene Knockout Techniques; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D008807:Mice, Inbred BALB C; D009154:Mutation; D011897:Random Allocation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014122:Toxoplasma / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D014123:Toxoplasmosis / Q000201:enzymology*; D014611:Vaccination; D014774:Virulence
D007527:Isoenzymes; D011994:Recombinant Proteins; D007770:L-Lactate Dehydrogenase; C409676:lactate dehydrogenase 2; C409667:lactate dehydrogenase 1