Lietze Verena-U, Sims Kelly R, Salem Tamer Z, Geden Christopher J, Boucias Drion G
Entomology and Nematology Department, University of Florida, 970 Natural Area Drive, Gainesville, FL 32611, USA.
J Invertebr Pathol. 2009 Apr;101(1):49-55. doi: 10.1016/j.jip.2009.02.007. Epub 2009 Feb 28.
The MdSGHV is a double-stranded DNA virus that replicates in the salivary glands of infected adult house flies. Transmission of this non-occluded, enveloped virus is believed to be mediated orally via deposition and consumption of oral secretions composed of salivary gland secretions and crop contents. In this study, transmission electron micrographs of crops from infected flies showed numerous enveloped virions in the crop lumen adjacent to the cuticular intima, as well as on the hemocoel side in close vicinity to muscle cells. Oral treatments of newly emerged flies with viremic salivary gland homogenates, crop homogenates, or gradient-purified virus resulted in an average 44% infection. Virus released via oral secretion was infectious when ingested by newly emerged adult flies, resulting in an average 66% infection. Using quantitative real-time PCR, MdSGHV DNA was quantified in oral secretions and excreta obtained from viremic flies. Between 2 and 4 days post-infection (dpi), viral copy numbers in oral secretions increased exponentially and from 5 to 21 dpi each infected fly released an average 10(6) MdSGHV copies per feeding event. Excreta samples collected overnight from individual infected flies at 5 dpi contained an average 6.5 x 10(5) viral copies. Low but detectable infection rates were produced when newly emerged flies were challenged with excreta samples. In summary, evaluation of the quantity and infectivity of MdSGHV released by individual infected house flies clearly showed that deposition of oral secretions and excreta onto a shared food substrate is the main route of natural MdSGHV transmission among adult house flies.
MdSGHV是一种双链DNA病毒，在受感染的成年家蝇唾液腺中复制。这种无包涵体的包膜病毒据信通过由唾液腺分泌物和嗉囊内容物组成的口腔分泌物的沉积和摄取而经口传播。在本研究中，受感染家蝇嗉囊的透射电子显微镜图像显示，在靠近角质内膜的嗉囊腔内以及靠近肌肉细胞的血腔侧有大量包膜病毒粒子。用含病毒的唾液腺匀浆、嗉囊匀浆或梯度纯化病毒对新羽化的家蝇进行口服处理，平均感染率为44%。经口分泌释放的病毒被新羽化的成年家蝇摄取时具有传染性，平均感染率为66%。使用定量实时PCR对从感染病毒的家蝇获得的口腔分泌物和排泄物中的MdSGHV DNA进行定量。感染后2至4天（dpi），口腔分泌物中的病毒拷贝数呈指数增加，从5至21 dpi，每只受感染的家蝇每次进食事件平均释放10(6)个MdSGHV拷贝。在5 dpi时，从个体受感染家蝇过夜收集的排泄物样本平均含有6.5×10(5)个病毒拷贝。用排泄物样本挑战新羽化的家蝇时产生了低但可检测到的感染率。总之，对单个受感染家蝇释放的MdSGHV的数量和传染性的评估清楚地表明，口腔分泌物和排泄物在共享食物基质上的沉积是成年家蝇之间MdSGHV自然传播的主要途径。
