Proteins of the sweetpotato whitefly (Bemisia tabaci) have previously been known to interact with begomoviruses. Two additional proteins in our laboratory have been identified and validated to interact with capsid proteins (CPs) of monopartite and bipartite begomoviruses. The two proteins include a C2H2 zinc finger like protein (vesicular endothelial zinc finger like - vezf) and cyclic adenosine monophosphate (cAMP) dependent phosphodiesterase (PDE4). The interactions (protein-protein) interactions were first identified using a yeast two hybrid screen (Y2H). The interactions were further validated using a series of other in vitro approaches such as pull-down assays with glutathione-S-transferase (GST) tagged CPs and in vivo approaches including co-immunoprecipitation and confocal microscopy. vezf belongs to a most abundant class of transcription factors in insects. Virus-induced gene silencing (VIGS) indicated that Vezf silencing in the whitefly resulted in increased retention of targeted begomoviruses. dsRNA-based silencing and chemical inhibition of cAMP specific PDE4 (Rolipram) resulted in enhanced cAMP levels with higher virus retention. Conversely, dsRNA-based silencing and chemical inhibition of adenylyl cyclase (SQ22536) led to reduced cAMP levels and reduced virus retention. VIGS of cAMP and PDE4 also indicated the same. cAMP inhibition resulted in reduced transmission of targeted begomoviruses, whereas PDE4 inhibition resulted in increased transmission of begomoviruses.
