The novel self-amplifying mRNA (SAM) technology for vaccines consists of an engineered replication-deficient alphavirus genome encoding an RNA-dependent RNA polymerase and the gene of the target antigen. To validate the concept, the rabies glycoprotein G was chosen as antigen. The delivery system for this vaccine was a cationic nanoemulsion. To characterize the local tolerance, potential systemic toxicity and biodistribution of this vaccine, two nonclinical studies were performed. In the repeated dose toxicity study, the SAM vaccine was administered intramuscularly to rats on four occasions at two-week intervals followed by a four-week recovery period. SAM-related changes consisted of a transient increase in neutrophil count, alpha-2-macroglobulin and fibrinogen levels. Transient aspartate aminotransferase and alanine aminotransferase increases were also noted in females only. At necropsy, observations related to the elicited inflammatory reaction, such as enlargement of the draining lymph nodes were observed that were almost fully reversible by the end of the recovery period. In the biodistribution study, rats received a single intramuscular injection of SAM vaccine and then were followed until Day 60. Rabies RNA was found at the injection sites and in the draining lymph nodes one day after administration, then generally decreased in these tissues but remained detectable up to Day 60. Rabies RNA was also transiently found in blood, lungs, spleen and liver. No microscopic changes in the brain and spinal cord were recorded. In conclusion, these results showed that the rabies SAM vaccine was well-tolerated by the animals and supported the clinical development program.

中文翻译：

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新型狂犬病自扩增mRNA疫苗的重复给药和生物分布的非临床安全性评估。

用于疫苗的新型自扩增mRNA（SAM）技术由工程改造的复制缺陷型甲病毒基因组组成，该基因组编码RNA依赖性RNA聚合酶和靶抗原的基因。为了验证这一概念，选择了狂犬病糖蛋白G作为抗原。该疫苗的递送系统是阳离子纳米乳剂。为了表征该疫苗的局部耐受性，潜在的全身毒性和生物分布，进行了两项非临床研究。在重复剂量毒性研究中，SAM疫苗以四次两次以肌肉注射的方式给予大鼠，间隔为两周，随后为四周的恢复期。SAM相关的变化包括中性粒细胞计数，α-2-巨球蛋白和纤维蛋白原水平的短暂增加。暂时性天冬氨酸转氨酶和丙氨酸转氨酶的增加也仅在女性中发现。尸检时，观察到与引起的炎症反应有关的观察结果，如引流淋巴结肿大，到恢复期结束时几乎完全可逆。在生物分布研究中，大鼠接受了一次肌肉注射SAM疫苗，然后随访至第60天。给药后一天，在注射部位和引流淋巴结中发现狂犬病RNA，然后在这些组织中普遍下降，但仍可检测到直到第60天。狂犬病RNA还在血液，肺，脾脏和肝脏中短暂发现。没有记录到大脑和脊髓的微观变化。结论，