Proteomics of the Autographa californica Nucleopolyhedrovirus Budded Virions

Baculoviruses produce two progeny phenotypes during their replication cycles. The occlusion-derived virus (ODV) is responsible for initiating primary infection in the larval midgut, and the budded virus (BV) phenotype is responsible for the secondary infection. The proteomics of several baculovirus ODVs have been revealed, but so far, no extensive analysis of BV-associated proteins has been conducted. In this study, the protein composition of the BV of Autographa californica nucleopolyhedrovirus (AcMNPV), the type species of baculoviruses, was analyzed by various mass spectrometry (MS) techniques, including liquid chromatography-triple quadrupole linear ion trap (LC-Qtrap), liquid chromatography-quadrupole time of flight (LC-Q-TOF), and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF). SDS-PAGE and MALDI-TOF analyses showed that the three most abundant proteins of the AcMNPV BV were GP64, VP39, and P6.9. A total of 34 viral proteins associated with the AcMNPV BV were identified by the indicated methods. Thirteen of these proteins, PP31, AC58/59, AC66, IAP-2, AC73, AC74, AC114, AC124, chitinase, polyhedron envelope protein (PEP), AC132, ODV-E18, and ODV-E56, were identified for the first time to be BV-associated proteins. Western blot analyses showed that ODV-E18 and ODV-E25, which were previously thought to be ODV-specific proteins, were also present in the envelop fraction of BV. In addition, 11 cellular proteins were found to be associated with the AcMNPV BV by both LC-Qtrap and LC-Q-TOF analyses. Interestingly, seven of these proteins were also identified in other enveloped viruses, suggesting that many enveloped viruses may commonly utilize certain conserved cellular pathways.

杆状病毒在其复制周期中产生两种子代表型。包涵体衍生病毒（ODV）负责在幼虫中肠引发初次感染，而出芽病毒（BV）表型负责二次感染。几种杆状病毒ODV的蛋白质组学已被揭示，但到目前为止，尚未对BV相关蛋白进行广泛分析。在本研究中，通过多种质谱（MS）技术，包括液相色谱 - 三重四极杆线性离子阱（LC - Qtrap）、液相色谱 - 四极杆飞行时间（LC - Q - TOF）和基质辅助激光解吸电离 - 飞行时间（MALDI - TOF），对苜蓿银纹夜蛾核多角体病毒（AcMNPV，杆状病毒的模式种）的BV蛋白质组成进行了分析。SDS - PAGE和MALDI - TOF分析表明，AcMNPV BV中三种最丰富的蛋白质是GP64、VP39和P6.9。通过上述方法共鉴定出34种与AcMNPV BV相关的病毒蛋白。其中13种蛋白质，PP31、AC58/59、AC66、IAP - 2、AC73、AC74、AC114、AC124、几丁质酶、多角体包膜蛋白（PEP）、AC132、ODV - E18和ODV - E56，首次被鉴定为BV相关蛋白。蛋白质印迹分析表明，先前被认为是ODV特异性蛋白的ODV - E18和ODV - E25也存在于BV的包膜组分中。此外，通过LC - Qtrap和LC - Q - TOF分析发现11种细胞蛋白与AcMNPV BV相关。有趣的是，这些蛋白中的7种也在其他有包膜病毒中被鉴定出来，这表明许多有包膜病毒可能普遍利用某些保守的细胞途径。