Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521, USA.
Center for Infectious Disease and Vector Research, University of California, Riverside, CA 92521, USA.
J Gen Virol. 2021 Sep;102(9). doi: 10.1099/jgv.0.001652.
Transmission of the crinivirus, lettuce infectious yellows virus (LIYV), is determined by a minor coat protein (CPm)-mediated virion retention mechanism located in the foregut of its whitefly vector. To better understand the functions of LIYV CPm, chimeric CPm mutants engineered with different lengths of the LIYV CPm amino acid sequence and that of the crinivirus, lettuce chlorosis virus (LCV), were constructed based on bioinformatics and sequence alignment data. The 485 amino acid-long chimeric CPm of LIYV mutant, CPmP-1, contains 60 % (from position 3 to 294) of LCV CPm amino acids. The chimeric CPm of mutants CPmP-2, CPmP-3 and CPmP-4 contains 46 (position 3 to 208), 51 (position 3 to 238) and 41 % (position 261 to 442) of LCV CPm amino acids, respectively. All four mutants moved systemically, expressed the chimeric CPm and formed virus particles. However, following acquisition feeding of the virus preparations, only CPmP-1 was retained in the foreguts of a significant number of vectors and transmitted. In immuno-gold labelling transmission electron microscopy (IGL-TEM) analysis, CPmP-1 particles were distinctly labelled by antibodies directed against the LCV but not LIYV CPm. In contrast, CPmP-4 particles were not labelled by antibodies directed against the LCV or LIYV CPm, while CPmP-2 and -3 particles were weakly labelled by anti-LIYV CPm but not anti-LCV CPm antibodies. The unique antibody recognition and binding pattern of CPmP-1 was also displayed in the foreguts of whitefly vectors that fed on CPmP-1 virions. These results are consistent with the hypothesis that the chimeric CPm of CPmP-1 is incorporated into functional virions, with the LCV CPm region being potentially exposed on the surface and accessible to anti-LCV CPm antibodies.
菜明黄花叶病毒（LIYV）通过一种由次要外壳蛋白（CPm）介导的病毒粒子保留机制在其粉虱载体的前肠中进行传播。为了更好地理解 LIYV CPm 的功能，根据生物信息学和序列比对数据，构建了带有不同长度的 LIYV CPm 氨基酸序列和藜科病毒，即生菜褪绿病毒（LCV）氨基酸序列的嵌合 CPm 突变体。LIYV 突变体 CPmP-1 的 485 个氨基酸长的嵌合 CPm 含有 60%（从位置 3 到 294）的 LCV CPm 氨基酸。突变体 CPmP-2、CPmP-3 和 CPmP-4 的嵌合 CPm 分别含有 46（位置 3 到 208）、51（位置 3 到 238）和 41%（位置 261 到 442）的 LCV CPm 氨基酸。所有四个突变体都能系统地移动、表达嵌合 CPm 并形成病毒颗粒。然而，在用病毒制剂进行取食后，只有 CPmP-1 在前肠中大量被保留下来并进行传播。在免疫金标记透射电子显微镜（IGL-TEM）分析中，CPmP-1 颗粒被针对 LCV 的抗体明显标记，但不被针对 LIYV CPm 的抗体标记。相比之下，CPmP-4 颗粒不被针对 LCV 或 LIYV CPm 的抗体标记，而 CPmP-2 和 CPmP-3 颗粒被针对 LIYV CPm 的抗体弱标记，但不被针对 LCV CPm 的抗体标记。CPmP-1 在取食 CPmP-1 病毒粒子的粉虱载体的前肠中也表现出独特的抗体识别和结合模式。这些结果与嵌合 CPmP-1 的 CPm 被整合到功能性病毒粒子中的假设一致，其中 LCV CPm 区域可能暴露在表面并可被针对 LCV CPm 的抗体识别。
