DEVELOPMENT OF A LEISHMANIA VACCINES

皮肤利什曼病每年仍影响约1000万人，尽管在控制病媒、消灭寄生虫和研制各种疫苗制剂方面做了许多努力。所有皮肤物种在人类自然感染后产生固体免疫。只有在皮肤利什曼病流行的地区，才尝试过用活寄生虫或利什曼化疫苗来预防该病。由于使用了活寄生虫，导致的病变常常伴有长期的溃疡和疤痕。使用灭活制剂的疫苗接种仅在少数人中显示出免疫原性，并且从未在大规模试验中显示出有效。最近对小鼠模型的观察表明，当将白细胞介素-12作为佐剂与利什曼原虫粗疫苗制剂一起使用时，可逆转易感BALB/c小鼠的免疫反应。与几家制药公司合作，我们正在开发一种用于人体临床试验的产品。虽然小鼠模型已经显示几种抗原与IL-12联合使用时是有效的，但迫切需要确认用细胞因子佐剂接种人的潜力，并确保粗制剂的安全性和免疫原性。我们已经用小鼠和恒河猴完成了一系列实验，以测试几种制剂的安全性、效力、功效和稳定性。疫苗抗原是在我们的实验室里从寄生虫培养物中提取出来的，这些培养物经过清洗，然后冷冻和解冻几次以破坏细胞。这些粗利什曼原虫制剂被证明，尽管高压灭菌，工作良好，高压灭菌后的制剂在37℃下保持稳定一个月。IND已提交I/II期临床试验，目前处于临床搁置状态。其他疫苗策略的临床前研究已经启动，包括DNA疫苗接种和使用CpG寡核苷酸作为佐剂。

Cutaneous leishmaniasis still affects about 10 million people a year, despite numerous attempts at vector control, parasite eradication, and creation of various vaccine formulations. Solid immunity develops after natural infection in humans with all cutaneous species. Vaccination against the disease with living parasites, or leishmanization, has only been tried in areas where cutaneous leishmaniasis is endemic. The lesion induced is often complicated by prolonged ulceration and scarring since live parasites are used. Vaccination with killed preparations has only been shown to be immunogenic in small numbers of people, and has never been shown to be effective in large trials. Recent observations using the mouse model have shown that Interleukin-12 can reverse the immune response of susceptible BALB/c mice when used as an adjuvant with a crude leishmania vaccine preparation. With the cooperation of several pharmaceutical companies, we are developing a product for use in human clinical trials. While the mouse model has shown several antigens to be efficacious when combined with IL-12, there is an urgent need to confirm the potential for vaccination in humans with the cytokine adjuvant, and to assure the community of the safety and immuno- genicity of a crude preparation. We have completed a series of experiments using mice and rhesus macaques to test the safety, potency, efficacy, and stability of several preparations. The vaccine antigen was made in our labs from cultures of parasites that are washed, then frozen and thawed several times to break the cells. These crude leishmania preps were shown to work well despite autoclaving, and the autoclaved preparation remains stable after one month at 37!C. An IND has been submitted for the Phase I/II clinical trial, which is currently on clinical hold. Preclinical studies for other vaccine strategies have been initiated including DNA vaccination and the use of CpG oligonucleotides as an adjuvant.