Advanced Centre for Preclinical Toxicology Studies, ICMR-National Institute of Nutrition, Jamai-Osmania, Hyderabad 500007, India.
Department of Microbiology and Immunology, ICMR-National Institute of Nutrition, Jamai-Osmania, Hyderabad 500007, India.
Vaccine. 2021 Jan 29;39(5):853-863. doi: 10.1016/j.vaccine.2020.11.023. Epub 2020 Dec 31.
The human papilloma virus (HPV) type 16 and 18 causes nearly 70% of uterine cervical cancers. Oral administration of live Salmonella typhi Ty21a, expressing major capsid proteins (L1) of HPV 16 and 18 is a potential choice for immunization in adolescent girls under low resource settings. Present study aimed to assess the nonclinical safety of recombinant S. typhi expressing HPV 16 and 18 (rStHPV) proteins.
The acute toxicity of rStHPV was tested by intranasal single dose administration, of 10 and 50 folds higher than clinical prophylactic dose, in mice and rat followed by monitoring their survival for 14 days. Sub-chronic toxicity was evaluated in rats and rabbits with prophylactic and 5 times (average) to clinical prophylactic dosages on scheduled days (1st, 3rd & 5th day) through oral and intranasal routes. The immune/allergic response of rStHPV was assessed in mice through intranasal and intra-peritoneal routes. Experimental animals were daily monitored for live phase, and clinical chemistry, haematology, immunotoxicology, immunogenic response and histopathological examination of vital organs on 15th, 29th and 93rd days.
No abnormal changes were noticed in live phase activity, clinical chemistry and haematology profile. The gross necropsy, organ weights and histopathology were found to be normal. No immunotoxicity was recorded as evaluated by tier I tests. Allergic immune response, as evaluated with IgE levels was also negative irrespective of test routes. On the other hand, a significant (P < 0.01) increase of anti-HPV IgG levels was noted in mice exposed through intranasal route. Though the pre-terminal mortality was noted in mice (6-15%), rats (10%) and rabbits (15%), the autopsy revealed no signs of toxicity related to rStHPV, as the changes neither significant nor dose dependent; and even noted in vehicle control also.
The study results suggested 'no observable adverse effects' of rStHPV even at higher dosages (5, 10 & 50 folds) than intended clinical dose. A significant increase of anti-HPV specific IgG suggests the immunogenicity of vaccine. The innovative approach of current study is nonclinical toxicology evaluation of vaccine through intra-nasal route, an alternate route apart from stipulated regulatory guidelines.
人乳头瘤病毒（HPV）16 型和 18 型导致近 70%的宫颈癌。在资源匮乏的环境下，对青少年女孩进行口服活伤寒沙门氏菌 Ty21a（表达 HPV 16 和 18 的主要衣壳蛋白（L1））免疫接种是一种潜在的选择。本研究旨在评估表达 HPV 16 和 18 型（rStHPV）蛋白的重组伤寒沙门氏菌的非临床安全性。
通过鼻腔内单次给药，给予比临床预防剂量高 10 倍和 50 倍的 rStHPV，检测其急性毒性，然后监测小鼠和大鼠的存活情况 14 天。通过鼻腔内和口服途径，以预防剂量和临床预防剂量的 5 倍（平均）在预定天数（第 1、3 和 5 天）给予 rStHPV，在大鼠和兔子中评估亚慢性毒性。通过鼻腔内和腹腔内途径，在小鼠中评估 rStHPV 的免疫/过敏反应。每天监测实验动物的生存阶段以及临床化学、血液学、免疫毒性、免疫原性反应和第 15、29 和 93 天的重要器官的组织病理学检查。
未观察到生命阶段活动、临床化学和血液学参数的异常变化。大体解剖、器官重量和组织病理学检查均正常。通过一级测试评估未发现免疫毒性。无论测试途径如何，用 IgE 水平评估的过敏免疫反应也是阴性的。另一方面，鼻腔内暴露的小鼠的抗 HPV IgG 水平显著（P<0.01）增加。尽管在小鼠（6-15%）、大鼠（10%）和兔子（15%）中观察到终末期死亡率，但尸检未发现与 rStHPV 相关的毒性迹象，因为变化既不显著也不剂量依赖性；甚至在载体对照组中也有发现。
即使在比预期临床剂量高 5、10 和 50 倍的剂量下，研究结果也表明 rStHPV 没有“可观察到的不良影响”。抗 HPV 特异性 IgG 的显著增加表明疫苗具有免疫原性。本研究的创新方法是通过鼻腔内途径（除规定的监管指南外的另一种途径）进行疫苗的非临床毒理学评估。
