Cross-reactive and major virus-specific epitopes are located at the N-terminal halves of the cylindrical inclusion proteins of turnip mosaic and zucchini yellow mosaic potyviruses

Abstract

To investigate the antigenic nature of cylindrical inclusion proteins (CIPs) of the potyviruses Turnip mosaic virus (TuMV) and Zucchini yellow mosaic virus (ZYMV), monoclonal antibodies (MAbs) against the two CIPs were produced and epitopes on the CIPs were localized using Escherichia coli-expressed CIP fragments in Western blot analysis. All 23 MAbs against ZYMV CIP reacted only with ZYMV CIP. In contrast out of the 18 MAbs produced against TuMV CIP, 14 MAbs were TuMV CIP-specific while the remaining four MAbs cross-reacted with both CIPs. The four cross-reactive MAbs recognized two distinct epitopes in the N-terminal half of TuMV CIP corresponding to amino acid residues 103-119 and 224-237. Thirteen out of 14 TuMV CIP-specific MAbs recognized two distinct epitopes within residues 1-102 and 120-214, while the other one recognized an epitope within residues 301-644. On the other hand, 21 out of 23 ZYMV CIP-specific MAbs recognized epitopes within residues 1-118, while the remaining two recognized epitopes within residues 301-522. These results suggest that cross-reactive and major virus-specific epitopes are located at the N-terminal half of the respective CIPs.

Analysis of the Epitope Structure of Plum pox virus Coat Protein

“…Extensive or significant antigenic studies are available for several other potyviruses, including Johnsongrass mosaic virus (42,43), Zucchini yellow mosaic virus (ZYMV) (18,33), Clover yellow vein virus (27), Potato virus Y (14), or Bean yellow mosaic virus (24,25). These studies used different strategies to identify specific epitopes, including PEPSCAN analysis (18,43) or the use of CP or CP derivatives expressed in Escherichia coli (14,25,33), often in conjunction with CP sequence comparison between isolates showing differential reactivity.…”

“…Extensive or significant antigenic studies are available for several other potyviruses, including Johnsongrass mosaic virus (42,43), Zucchini yellow mosaic virus (ZYMV) (18,33), Clover yellow vein virus (27), Potato virus Y (14), or Bean yellow mosaic virus (24,25). These studies used different strategies to identify specific epitopes, including PEPSCAN analysis (18,43) or the use of CP or CP derivatives expressed in Escherichia coli (14,25,33), often in conjunction with CP sequence comparison between isolates showing differential reactivity. The general picture of potyvirus antigenicity which emerges is that epitopes with narrow specificity or virus-specific epitopes are located on the surface-exposed N-and C-terminal variable regions of the CP (42), while epitopes showing broad specificity and allowing the recognition of different viral species are located in the conserved internal core of the CP (31,43).…”

Turnip mosaic virusand the quest for durable resistance

“…Potyviral CI initially accumulates around plasmodesmata, where it is thought to have an important role in the cell‐to‐cell transport of viral nucleic acids (Roberts et al ., 1998). The N‐terminus appears to be the more conserved region, being the location of at least two cross‐reactive epitopes (Kundu et al ., 2000), as well as the region containing the characteristic DEXH motifs of the helicase superfamily 2. The 3′ to 5′ helicase activity unwinds dsRNA (Lain et al ., 1990) and is thus vital for replication (Klein et al ., 1994).…”