Transient expression of cauliflower mosaic virus (CaMV) P6-GFP complements a defective CaMV replicon to facilitate viral gene expression, replication and virion formation

Virology. 2023 Oct:587:109854. doi: 10.1016/j.virol.2023.109854. Epub 2023 Aug 1.

Abstract

Over the past decades, several studies have examined the subcellular localization of the cauliflower mosaic virus (CaMV) P6 protein by tagging it with GFP (P6-GFP). These investigations have been essential in the development of models for inclusion body formation, nuclear transport, and microfilament-associated intracellular movement of P6 inclusion bodies for delivery of virions to plasmodesmata. Although it was shown early on that the translational transactivation function of P6-GFP was comparable to wild type P6, it has not been possible to incorporate a P6-GFP gene into an infectious clone of CaMV. Consequently, it has not been possible to formally prove that a P6-GFP fusion is comparable in function to the unmodified P6 protein. Here we show that transient expression of P6-GFP can complement a defective CaMV replicon through gene expression, replication and encapsidation, which validates the relevance of P6-GFP subcellular localization studies for understanding the development of CaMV infections.

Keywords: Agroinfiltration; Caulimoviruses; Protein-GFP fusions; Virion factories; Virions.