Abstract:  Objective  To observe the proteome changes in the hippocampus tissue of rats with chronic Toxoplasma gondii infection.  Methods  Six male SD rats were randomly divided into control group and infection group. Each rat in infection group was intraperitoneally injected with 4×107 purified T. gondii tachyzoites. Rats in the control group received equivalent volumes of sterile normal saline. At the fifth day post-infection, blood samples were taken from the lateral tail vein and Giemsa staining of blood cells was performed to find Toxoplasma gondii. Rats were dissected at the 10th week post-infection, total protein in the hippocampus was separated by using two-dimensional gel electrophoresis（2-DE）. After Coomassie blue staining, the Image Analysis software was used to select and separate proteins on the gel. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry（MALDI-TOF-MS） was used for peptide mass fingerprint （PMF）. Proteins were identified by using Mascot software to search the MSDB and SwissProt databases.  Results  Microscopy examination of blood smears confirmed that the rats in infection group were all infected by T. gondii. The number of protein spots of rats from infection group and control group was 311±19 and 327±13, respectively. Compared with the control group, 5 protein spots disappeared, 4 protein spots were up-regulated and 7 were down-regulated in the infection group. The 9 differentially expressed protein spots were identified by MALDL-TOF-MS: phosphoglycerate kinase 1, similar to alpha-enolase, glutamine synthetase, creatine kinase, creatine kinase B-type, ATP synthase, aconitase 2, mitochondrial precursor, actin and an unnamed protein. The first three proteins were up-regulated and the other five proteins were down-regulated in infection group. 　Conclusion  Nine differential expression proteins are found from the hippocampus tissue in rats chronically infected with T. gondii and normal SD rats.

Key words: Toxoplasma gondii, Rat, Hippocampus, Proteomics