Heisey G B, Shirai A, Groves M G
Jpn J Med Sci Biol. 1982 Oct-Dec;35(5-6):235-8. doi: 10.7883/yoken1952.35.235.
The effect of age on the susceptibility of ICR mice to lethal intraperitoneal (ip), Rickettsia tsutsugamushi infections was tested with five virulent strains--Karp, Kato, Gilliam, TA763, and TH1817--and three strains of reduced virulence--TA678, TA686, and TA716. Susceptibility differences were noted only in the ICR mice inoculated with two of the strains of reduced virulence, TA716 and TA678. With both strains, mice in the 12-weeks and younger age groups had lower death rates than did mice in the 21-weeks and older age groups. Also, CBA/CaJ mice of varying ages were inoculated intravenously with large doses of the Gilliam strain to determine the effect of age on susceptibility to acute death syndrome (ADS). A progressive increase in ADS resistance was seen in the 4-, 8-, 12-, and 16-week-old age groups. This study indicates that the age of mice used to test the virulence of R. tsutsugamushi strains may be an important consideration, especially when testing the ip lethality of strains of reduced virulence.
用五种强毒株（卡尔普、加藤、吉列姆、TA763和TH1817）和三种弱毒株（TA678、TA686和TA716）测试了年龄对ICR小鼠经腹腔注射致死性恙虫病东方体感染易感性的影响。仅在接种了两种弱毒株TA716和TA678的ICR小鼠中观察到易感性差异。对于这两种毒株，12周龄及以下年龄组的小鼠死亡率低于21周龄及以上年龄组的小鼠。此外，给不同年龄的CBA/CaJ小鼠静脉注射大剂量的吉列姆毒株，以确定年龄对急性死亡综合征（ADS）易感性的影响。在4周、8周、12周和16周龄的年龄组中，观察到对ADS的抵抗力逐渐增强。这项研究表明，用于测试恙虫病东方体毒株毒力的小鼠年龄可能是一个重要的考虑因素，尤其是在测试弱毒株的腹腔注射致死率时。
