Tsai C W, McGraw E A, Ammar E-D, Dietzgen R G, Hogenhout S A
Department of Entomology, The Ohio State University-OARDC, Wooster, Ohio 44691, USA.
Appl Environ Microbiol. 2008 May;74(10):3251-6. doi: 10.1128/AEM.02248-07. Epub 2008 Mar 31.
Rhabdoviruses are important pathogens of humans, livestock, and plants that are often vectored by insects. Rhabdovirus particles have a characteristic bullet shape with a lipid envelope and surface-exposed transmembrane glycoproteins. Sigma virus (SIGMAV) is a member of the Rhabdoviridae and is a naturally occurring disease agent of Drosophila melanogaster. The infection is maintained in Drosophila populations through vertical transmission via germ cells. We report here the nature of the Drosophila innate immune response to SIGMAV infection as revealed by quantitative reverse transcription-PCR analysis of differentially expressed genes identified by microarray analysis. We have also compared and contrasted the immune response of the host with respect to two nonenveloped viruses, Drosophila C virus (DCV) and Drosophila X virus (DXV). We determined that SIGMAV infection upregulates expression of the peptidoglycan receptor protein genes PGRP-SB1 and PGRP-SD and the antimicrobial peptide (AMP) genes Diptericin-A, Attacin-A, Attacin-B, Cecropin-A1, and Drosocin. SIGMAV infection did not induce PGRP-SA and the AMP genes Drosomycin-B, Metchnikowin, and Defensin that are upregulated in DCV and/or DXV infections. Expression levels of the Toll and Imd signaling cascade genes are not significantly altered by SIGMAV infection. These results highlight shared and unique aspects of the Drosophila immune response to the three viruses and may shed light on the nature of the interaction with the host and the evolution of these associations.
弹状病毒是人类、家畜和植物的重要病原体，常通过昆虫传播。弹状病毒颗粒具有特征性的子弹形状，带有脂质包膜和表面暴露的跨膜糖蛋白。西格玛病毒（SIGMAV）是弹状病毒科的成员，是黑腹果蝇的一种自然发生的病原体。该感染通过生殖细胞的垂直传播在果蝇种群中得以维持。我们在此报告通过对微阵列分析鉴定出的差异表达基因进行定量逆转录 - PCR分析所揭示的果蝇对SIGMAV感染的先天免疫反应的性质。我们还比较和对比了宿主对两种无包膜病毒，即果蝇C病毒（DCV）和果蝇X病毒（DXV）的免疫反应。我们确定SIGMAV感染上调了肽聚糖受体蛋白基因PGRP - SB1和PGRP - SD以及抗菌肽（AMP）基因双翅菌素 - A、攻击素 - A、攻击素 - B、天蚕素 - A1和果蝇抗菌肽的表达。SIGMAV感染并未诱导在DCV和/或DXV感染中上调的PGRP - SA以及AMP基因果蝇霉素 - B、梅契尼科夫菌素和防御素。SIGMAV感染对Toll和Imd信号级联基因的表达水平没有显著影响。这些结果突出了果蝇对这三种病毒免疫反应的共同和独特方面，并可能有助于揭示与宿主相互作用的性质以及这些关联的进化。
