Detection, isolation and characterization of cowpea mosaic virus in Egypt

Abstract

Cowpea mosaic virus is among the most economically important viruses infecting cowpea. Incidence of infection was assessed in two governorates in Egypt, namely Alexandria and El Beheira. An overall infection rate of 6% in 200 collected samples was verified by ELISA indicating the presence, but not spread of the virus in selected areas. A CPMV isolate has been propagated in Kafr El Sheikh1 cowpea cultivar, followed by virus purification. Thin-section electron microscopy revealed cytopathological effects due to viral infection. Both CP S and CP L components of CPMV-egn coat protein of 37 kDa and 23 kDa were detected by SDS-PAGE. Following RNA purification, RNA1 (5000 bp) and RNA2 (3000 bp) were detected. Amplification of CPMV-egn coat protein gene (476 bp) and polymerase gene (716 bp) was followed by cloning and sequencing. Both sequences received accession numbers of KT456532 and KT456533 from Genbank, respectively. Phylogenetic analysis has revealed that the Egyptian CPMV-egn isolate shares more sequence homology to UK isolates, more than 2 Egyptian isolates reported earlier. However, CPMV-egn seems distinct from the closely related UK isolates. This observation may be an indication of genetic diversity of CPMV in Egypt.