HIV-1 V2区突变对CD4结合位点中和抗体识别的影响

目的 探讨HIV-1病毒包膜蛋白gp120的V2区突变对其他结构域的中和抗体识别的影响。 方法 使用假病毒构建系统包装野生型和V2区突变型的HIV-1假病毒,分别测试抗CD4结合位点中和抗体和CD4诱导的中和抗体对两种病毒的中和作用。使用双抗体夹心ELISA法测试CD4结合位点中和抗体和CD4诱导的中和抗体对gp120野生型和突变型蛋白的亲合力。结果 CD4结合位点中和抗体和CD4诱导的中和抗体均无法中和野生株JR-FL WT假病毒,但2种中和抗体对V2突变株的中和活性显著提高,在低浓度下即可中和该病毒。野生株和突变株gp120单体与抗CD4结合位点中和抗体的结合力无明显差异,而gp120单体与CD4诱导的中和抗体的结合实验ELISA曲线却明显分离,CD4诱导的中和抗体与突变型JR-FL L175P gp120的结合强度均明显高于它们与野生型JR-FL WT gp120的结合强度。结论 HIV-1 V2区突变可影响中和抗体的抗病毒效果。     

Use of Protease Inhibitors to Improve Calcitonin Absorption from the Small and Large Intestine in Rats

The objective of this study was to examine the effects of protease inhibitors on the absorption of calcitonin from different regions of the intestine in rats. The absorption experiments were investigated by in-situ use of closed intestinal loops in rats and stability of calcitonin was examined in mucosal homogenates and intestinal fluids. The intestinal absorption of calcitonin was evaluated by measurement of its hypocalcaemic effect. No substantial hypocalcaemic response was observed when calcitonin was administered into the jejunum or colon. A slight hypocalcaemic effect was observed after administration of calcitonin into the ileum. Of the co-administered protease inhibitors, bacitracin (20 mM) strongly promoted calcitonin absorption from the jejunum, ileum and colon. A significant hypocalcaemic effect was also obtained after intestinal administration of calcitonin with soybean trypsin inhibitor (10mgmL^?1), camostat mesylate (20mM) or aprotinin (2mgmL^?1). In the stability experiment, bacitracin reduced the degradation of calcitonin in the different intestinal homogenates. Soybean trypsin inhibitor significantly reduced the degradation of calcitonin in the fluids of the small intestine. We also examined the different endopeptidases in gut luminal fluids and the different exopeptidases in gut mucosal homogenates of rats. The ranking order for the total endopeptidase activity of the intestinal fluids was jejunum > ileum > colon. That for total exopeptidase activity of the intestinal mucosa was jejunum > ileum > colon. These results suggest that endo- and exopeptidases might be responsible for the hydrolysis of calcitonin and that protease inhibitors might usefully improve absorption of calcitonin to the systemic circulation from the large intestine.