Department of Microbiology and Molecular Biology, Brigham Young University, WIDB 893, Provo, UT 84602, USA.
J Med Entomol. 2012 Mar;49(2):364-70. doi: 10.1603/me11172.
Fleas are vectors for a number of pathogens including Yersinia pestis, yet factors that govern interactions between fleas and Y. pestis are not well understood. Examining gene expression changes in infected fleas could reveal pathways that affect Y. pestis survival in fleas and subsequent transmission. We used suppression subtractive hybridization to identify genes that are induced in Xenopsylla cheopis (Rothschild) (Siphonaptera: Pulicidae) in response to oral or hemocoel infection with Y. pestis. Overall, the transcriptional changes we detected were very limited. We identified several genes that are likely involved in the production or removal of reactive oxygen species (ROS). Midgut ROS levels were higher in infected fleas and antioxidant treatment before infection reduced ROS levels and resulted in higher bacterial loads. An ROS-sensitive mutant strain of Y. pestis lacking the OxyR transcriptional regulator showed reduced growth early after infection. Our results indicate that ROS may limit Y. pestis early colonization of fleas and that bacterial strategies to overcome ROS may enhance transmission.
跳蚤是多种病原体的传播媒介，包括鼠疫耶尔森菌，但控制跳蚤与鼠疫耶尔森菌相互作用的因素还不太清楚。研究感染跳蚤的基因表达变化可以揭示影响鼠疫耶尔森菌在跳蚤中存活和随后传播的途径。我们使用抑制性消减杂交来鉴定感染鼠疫耶尔森菌的印鼠客蚤（罗氏）（蚤目：蚤科）中受诱导的基因。总的来说，我们检测到的转录变化非常有限。我们鉴定了几个可能参与活性氧（ROS）产生或清除的基因。感染跳蚤的中肠 ROS 水平较高，感染前的抗氧化处理降低了 ROS 水平，并导致更高的细菌载量。缺乏转录调节因子 OxyR 的 ROS 敏感突变株在感染后早期生长缓慢。我们的结果表明，ROS 可能限制鼠疫耶尔森菌早期在跳蚤中的定植，而细菌克服 ROS 的策略可能会增强传播。
