[Cloning and expression of actin gene of Toxoplasma gondii].

OBJECTIVE: To clone and express the actin gene of Toxoplasma gondii, and analyze the immunoreactivity of the recombinant protein. METHODS: Total RNA was extracted from tachyzoites of RH strain of T. gondii. The open reading frame of TgACT gene was amplified with a pair of specific primers which were designed according to the coding sequence of TgACT gene (Accession No. XM_002369622.1). The RT-PCR product was cloned into the prokaryotic expression pET-30a (+) vector. The recombinant pET30a-TgACT plasmid was transformed into E. coli DH5alpha. The positive clones were selected through the colony-PCR and confirmed by the double restrict enzyme digestion and sequencing. The correct pET30a-TgACT plasmid was transformed into E. coli BL21(DE3) and induced by IPTG. The expressed proteins were analyzed by SDS-PAGE. Western blotting assay was performed with anti-poly-histidine tag (anti-His) antibody or rabbit anti-T. gondii serum. RESULTS: The product of RT-PCR was with 1 100 bp. The recombinant plasmid pET30a-TgACT was confirmed by colony-PCR, double restriction enzyme digestion and sequencing. SDS-PAGE results showed that the target protein was expressed in E. coli BL21(DE3) in the form of inclusion bodies with a rough molecular weight of 49 000. The purified soluble protein was obtained by using denaturation, renaturation and purification. Western blotting revealed that rTgACT can be recognized by anti-His antibody and rabbit anti-T. gondii serum. CONCLUSION: The recombinant plasmid pET30a-TgACT has been successfully constructed, and the recombinant protein TgACT is produced in E. coli and maintains specific immunoreactivity.

Influence of arm position change from adduction to abduction on intracavitary electrocardiogram.

PURPOSE: The aim of this study is to evaluate the influence of arm movements from adduction to abduction on intracavitary electrocardiogram and the position of a catheter tip. METHODS: Overall, 192 peripherally inserted central catheter lines were placed under intracavitary electrocardiogram guidance and 188 of them were enrolled in the study. The catheter was first placed at a time point corresponding to the peak P wave with the arm in adduction. The arm was then abducted to 90° without changing catheter insertion length. During the procedure, basal electrocardiogram, intracavitary electrocardiogram, and radiographs with the arm in adduction and abduction were recorded. Amplitude wave changes and catheter movements were measured on electrocardiogram records and radiographs, respectively. RESULTS: In 188 cases, the P wave displayed typical changes, and 97.8% (184/188) catheters were successfully placed correctly. At the peak P wave, the amplitude of the peak P wave was 8.64 times greater than that of the basal P wave, and the P/R ratio was 0.61. When the arm was abducted to 90°, the amplitude of the P wave dropped to 57% of its peak, P/R decreased from 0.61 to 0.34, and the catheter tip moved cephalad 1.00 and 0.77 vertebral body units in male and female patients, respectively. CONCLUSION: Peripherally inserted central catheter moves toward the heart when the arm position changes from abduction to adduction. Peripherally inserted central catheter tip placement at the peak P wave with patient's arm in adduction is accurate and can prevent the catheter from advancing too low. R wave can function as a reference for observing P wave changes during peripherally inserted central catheter placement.

Intranasal immunisation with recombinant Toxoplasma gondii actin partly protects mice against toxoplasmosis.

Toxoplasma gondii is a ubiquitous protozoan intracellular parasite, the causative agent of toxoplasmosis, and a worldwide zoonosis for which an effective vaccine is needed. Actin is a highly conserved microfilament protein that plays an important role in the invasion of host cells by T. gondii. This study investigated the immune responses elicited by BALB/c mice after nasal immunisation with a recombinant T. gondii actin (rTgACT) and the subsequent protection against chronic and lethal T. gondii infections. We evaluated the systemic response by proliferation, cytokine and antibody measurements, and we assessed the mucosal response by examining the levels of TgACT-specific secretory IgA (SIgA) in nasal, vaginal and intestinal washes. Parasite load was assessed in the liver and brain, and the survival of mice challenged with a virulent strain was determined. The results showed that the mice immunised with rTgACT developed high levels of specific anti-rTgACT IgG titres and a mixed IgG1/IgG2a response with a predominance of IgG2a. The systemic immune response was associated with increased production of Th1 (IFN-γ and IL-2), Th2 (IL-4) and Treg (IL-10) cytokines, indicating that not only Th1-type response was induced, but also Th2- and Treg-types responses were induced, and the splenocyte stimulation index (SI) was increased in the mice immunised with rTgACT. Nasal immunisation with rTgACT led to strong mucosal immune responses, as seen by the increased secretion of SIgA in nasal, vaginal and intestinal washes. The vaccinated mice displayed significant protection against lethal infection with the virulent RH strain (survival increased by 50%), while the mice chronically infected with RH exhibited lower liver and brain parasite loads (60.05% and 49.75%, respectively) than the controls. Our data demonstrate, for the first time, that actin triggers a strong systemic and mucosal response against T. gondii. Therefore, actin may be a promising vaccine candidate against toxoplasmosis.