DETECTION AND IDENTIFICATION OF CUCUMBER MOSAIC VIRUS ISOLATE FROM RED CURRANT 'ROSETTA'

Cucumber mosaic virus was detected using enzyme-linked immunosorbent assay (ELISA) in a symptomless red currant plant ‘Rosetta’, during routine testing in the nursery in central Poland. Mild leaf mosaic and vein yellowing symptoms were observed on the same plant a year later. Serological properties of the virus (isolate PORZ) were determined using ELISA with four polyclonal antibodies: commercially available CMV-I and CMV-II specific for subgroup I and II, respectively (Agdia), and antisera locally prepared against CMV isolates M and Wic belonging to subgroup I and II, respectively. The red currant isolate (PORZ) reacted positively with antibodies M, Wic and CMV-II, but did not react with CMV-I antibodies. The coat protein (CP) of isolate PORZ co-migrated in SDS-PAGE with the CP of isolates belonging to CMV subgroup II, faster than the CP of CMV-I isolates. The CP was detected in western blots with polyclonal antiserum against CMV. Fragments of the PORZ RNA3 were reverse transcribed and amplified using immunocapture reverse transcription-polymerase chain reaction (IC-RT-PCR) and sequenced. The PORZ isolate had greater than 95% nucleotide sequence identity in the CP and 3a genes with the members of CMV subgroup II, and less than 80% sequence identity with CMV-I isolates. The identity of isolate PORZ in deduced amino acid sequence of the coat protein with CMV II isolates was 96% or higher, and less than 87% with CMV-I isolates. On the basis of these results, isolate PORZ was classified as a member of subgroup II of CMV.