The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells.
Insect transmission is an essential process of infection for numerous plant and animal viruses. How an insect-transmissible plant virus enters an insect cell to initiate the infection cycle is poorly understood, especially for nonenveloped plant and animal viruses. The capsid protein P2 of rice dwarf virus (RDV), which is nonenveloped, is necessary for insect transmission. Here, we present evidence that P2 shares structural features with membrane-fusogenic proteins encoded by enveloped animal viruses. When RDV P2 was ectopically expressed and displayed on the surface of insect Spodoptera frugiperda cells, it induced membrane fusion characterized by syncytium formation at low pH. Mutational analyses identified the N-terminal and a heptad repeat as being critical for the membrane fusion-inducing activity. These results are corroborated with results from RDV-infected cells of the insect vector leafhopper. We propose that the RDV P2-induced membrane fusion plays a critical role in viral entry into insect cells. Our report that a plant viral protein can induce membrane fusion has broad significance in studying the mechanisms of virus entry into insect cells and insect transmission of nonenveloped plant and animal viruses.
The National Laboratory of Protein Engineering and Plant Genetic Engineering, Peking-Yale Joint Center for Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China.
Feng
F
Zhou
Yingying
Y
Pu
Taiyun
T
Wei
Taiyuan
T
Wei
Huijun
H
Liu
Wulan
W
Deng
Chunhong
C
Wei
Biao
B
Ding
Toshihiro
T
Omura
Yi
Y
Li
D000595:Amino Acid Sequence; D000818:Animals; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012087:Reoviridae / Q000502:physiology*; D018411:Spodoptera / Q000821:virology*; D014760:Viral Fusion Proteins / Q000737:chemistry; D053586:Virus Internalization
D036022:Capsid Proteins; D014760:Viral Fusion Proteins; C108379:protein P2, rice dwarf phytoreovirus