Zhang Jian-Zhi, Hao Jun-Fang, Walker David H, Yu Xue-Jie
Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
Vaccine. 2006 Mar 20;24(13):2317-23. doi: 10.1016/j.vaccine.2005.11.044. Epub 2005 Dec 5.
Rickettsia prowazekii Madrid E (E) strain is an effective vaccine, but can revert to virulent status when passaged in animals. The aim of this study is to identify the reverse mutation that may determine the virulence of R. prowazekii by comparing the genetic structures of E strain and its virulent revertant Evir strain. We determined that the gene (Rp028/Rp027) encoding the methyltransferase was mutated by frameshift in avirulent E strain but not in virulent revertant Evir strain and wild type virulent Breinl strain. We conclude that the mutation in the E strain gene reverts to wild type in the virulent revertant Evir strain. Whether the mutation plays an essential role in the attenuation of E strain needs to be further investigated.
普氏立克次体马德里E（E）株是一种有效的疫苗，但在动物体内传代时可恢复为有毒状态。本研究的目的是通过比较E株及其有毒回复株Evir株的遗传结构，确定可能决定普氏立克次体毒力的反向突变。我们确定，编码甲基转移酶的基因（Rp028/Rp027）在无毒E株中因移码而发生突变，但在有毒回复株Evir株和野生型有毒布雷因尔株中未发生突变。我们得出结论，E株基因中的突变在有毒回复株Evir株中恢复为野生型。该突变是否在E株的减毒中起关键作用有待进一步研究。
