A point mutation changes the serotype of a Potato virus Y isolate; genomic determination of the serotype of PVY strains

Abstract

A Syrian isolate of Potato virus Y (PVY), named PVY-12, reacted to two monoclonal antibodies that are specific to PVY(O,C) and PVY(N) strains, although its coat protein (CP) belongs to the PVY(N) strain. Analysis of the CP of PVY-12 revealed that a point mutation in its N terminus switched it from PVY(N)-like to PVY(O)-like at this position. This mutation changed the second nucleotide of the codon that encodes the 29th amino acid of the CP of PVY-12 from A to G, which resulted in one amino acid substitution from Glu(29 )to Gly(29). The role of Gly(29) in the binding of PVY-12 to PVY(O,C)-specific monoclonal antibody was confirmed by gene expression in Escherichia coli. The N terminus of the CP gene of PVY-12 and another PVY isolate of the N serotype with identical CP to PVY-12 except for one amino acid substitution from Gly(29 )to Glu(29) was cloned and expressed in E. coli using a pUC18 vector. Resulting antigens showed similar reactivity to the relevant antibodies as same as the native CPs of these two isolates. Further analysis of the CP of PVY isolates showed that Gly(29) was conserved in the CP of PVY(O), PVY(C), PVY(N)W, and non-potato isolates of PVY while Gln(17) and Glu(31 )were conserved in the CP of PVY(N/NTN). Therefore, these amino acids are characteristic of the CP for these strain groups and subgroups in agreement with the serotype and phylogenetic relationships previously determined.

Analysis of Potato virus Y Coat Protein Epitopes Recognized by Three Commercial Monoclonal Antibodies

“…A single amino acid substitution can abolish or create an epitope recognized by a MAb [32] . Chikh Ali et al [33] concluded that a glycine residue in CP at position 29 allows detection of the PVY N isolate PVY-12 with MAb2 that is supposed to detect PVY O and PVY C strains [26] , and also allows detection of PVY-12 with MAb 1F5 that reacts mainly with PVY N strains [28] . In contrast, PVY N -like isolates carrying a glutamic acid residue at position 29 are detected only with MAb 1F5 [33] .…”

“…Chikh Ali et al [33] concluded that a glycine residue in CP at position 29 allows detection of the PVY N isolate PVY-12 with MAb2 that is supposed to detect PVY O and PVY C strains [26] , and also allows detection of PVY-12 with MAb 1F5 that reacts mainly with PVY N strains [28] . In contrast, PVY N -like isolates carrying a glutamic acid residue at position 29 are detected only with MAb 1F5 [33] . Karasev et al [34] concluded that glutamine at position 98 of PVY CP is required for detection with MAb 1F5.…”

Molecular and Biological Characterization of Potato virus Y Isolates from Vietnam

“…This is the case for the isolate Syr‐12 (Chikh Ali et al. ), in which a point mutation induced reactivity of the CP with the PVY O ‐specific Agdia PVY O ‐MAb2: AA29 changed from Glu (E; GAA) to Gly (G; GGA).…”

Whole Genome Sequence and Characterization of a Novel Isolate of PVY Inducing Tuber Necrotic Ringspot in Potato and Leaf Mosaic in Tobacco

“…SYR‐NB‐16, the representative isolate of PVY SYR , shared characteristics with both PVY N W and PVY NTN due to the recombination between genomes of PVY N W and PVY NTN ancestor isolates (Chikh Ali et al., 2007a). In another study on PVY from Syria, the serological properties of a mutant isolate of PVY, referred to as PVY‐12, were reported (Chikh Ali et al., 2007b). This isolate reacted with two monoclonal antibodies specific to the N and O serotypes due to a point mutation in its CP (Chikh Ali et al., 2007b).…”

“…In another study on PVY from Syria, the serological properties of a mutant isolate of PVY, referred to as PVY‐12, were reported (Chikh Ali et al., 2007b). This isolate reacted with two monoclonal antibodies specific to the N and O serotypes due to a point mutation in its CP (Chikh Ali et al., 2007b). Moreover, PVY‐12 had a unique combination of biological properties as it belonged to PVY NTN according to its phenotype in potato and to PVY O according to its symptoms in tobacco.…”