Autographa californica multiple nucleopolyhedrovirus ODV-E56 is a per os infectivity factor, but is not essential for binding and fusion of occlusion-derived virus to the host midgut.
The Autographa californica multiple nucleopolyhedrovirus (AcMNPV) occlusion-derived virus (ODV) envelope protein ODV-E56 is essential for oral infection of larvae of Heliothis virescens. Bioassays with recombinant clones of AcMNPV lacking a functional odv-e56 gene showed that ODV-E56 was required for infectivity of both polyhedra and to a lesser extent, purified ODV. However, binding and fusion assays showed that ODV lacking ODV-E56 bound and fused to midgut cells at levels similar to ODV of wild-type virus. Fluorescence microscopy of midguts from larvae inoculated with ODV-E56-positive and -negative viruses that express GFP indicated that ODV-E56 was required for infection of the midgut epithelium. Purified ODV-E56 bound to several proteins in midgut-derived brush border membrane vesicles, but failed to rescue infectivity of ODV-E56-negative viruses in trans. These results indicate that ODV-E56 is a per os infectivity factor (pif-5) required for primary midgut infection at a point before or after virion binding and fusion.
Genetics Program, Department of Entomology, Iowa State University, Ames, IA 50011, USA. wendy.sparks@ars.usda.gov
Wendy O
WO
Sparks
Robert L
RL
Harrison
Bryony C
BC
Bonning
D000284:Administration, Oral; D000818:Animals; D002478:Cells, Cultured; D004064:Digestive System / Q000821:virology*; D004847:Epithelial Cells / Q000821:virology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000821:virology; D007915:Lepidoptera / Q000821:virology*; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity* / Q000502:physiology; D011995:Recombination, Genetic; D018411:Spodoptera / Q000821:virology; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
C098724:Ac-odv-e56 protein, Autographa californica nucleopolyhedrovirus; D008565:Membrane Proteins; D014759:Viral Envelope Proteins; D037521:Virulence Factors; D049452:Green Fluorescent Proteins