Nitric oxide stimulates early egress of Toxoplasma gondii tachyzoites from Human foreskin fibroblast cells.
BACKGROUND
Egress is a vital step in the life cycle of Toxoplasma gondii which attracts attentions of many groups. Previous studies have shown that exogenous nitric oxide (NO) stimulates the early egress of T. gondii from infected peritoneal macrophages, a kind of immune cells. However, because Toxoplasma forms cysts in brain and muscle tissues, the development of autonomous immunity in non-immune cells is vital for limiting parasite burden and cyst formation. Therefore, we attempted to investigate whether exogenous NO could induce the early egress of T. gondii from infected non-immune cells.


METHODS
T. gondii tachyzoites were cultured in human foreskin fibroblast (HFF) cells and were then treated with NO released by sodium nitroferricyanide (III) dihydrate (SNP). The egressed parasites were analysed by flow cytometry.


RESULTS
The results showed that NO induced the early egress of parasites from HFF cells before completing their intracellular life cycles. We also found that the occurrence of egress was dependent on intracellular calcium (Ca(2+)) levels and the mobility of the parasite. Compared with freshly isolated tachyzoites, the developmental ability and virulence of egressed tachyzoites presented no difference.


CONCLUSIONS
Taken together, our findings demonstrate a novel assay for the analysis of egress signalling mechanisms and an avenue of parasite clearance by hosts of T. gondii.
State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China. yanxinlei1987620@foxmail.com.|National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China. yanxinlei1987620@foxmail.com.
Xinlei
X
Yan
State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China. jiyongsheng@cau.edu.cn.|National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China. jiyongsheng@cau.edu.cn.
Yongsheng
Y
Ji
State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China. jiaotouliao1981@163.com.|National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China. jiaotouliao1981@163.com.|Key Laboratory of Zoonosis of Ministry of Agriculture & College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China. jiaotouliao1981@163.com.
Xianyong
X
Liu
State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China. suoxun@cau.edu.cn.|National Animal Protozoa Laboratory & College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China. suoxun@cau.edu.cn.|Key Laboratory of Zoonosis of Ministry of Agriculture & College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China. suoxun@cau.edu.cn.
Xun
X
Suo
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D020013:Calcium Signaling; D002478:Cells, Cultured; D005347:Fibroblasts / Q000469:parasitology*; D052816:Foreskin / Q000166:cytology*; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000494:pharmacology*; D009599:Nitroprusside / Q000737:chemistry / Q000494:pharmacology; D030781:Organisms, Genetically Modified; D013047:Specific Pathogen-Free Organisms; D014122:Toxoplasma / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology; D014774:Virulence
D001426:Bacterial Proteins; D008164:Luminescent Proteins; C054562:yellow fluorescent protein, Bacteria; D009599:Nitroprusside; D009569:Nitric Oxide