Partial characterization of Prunus Necrotic Ringspot Virus on apple in EGYPT

A severe isolate of Prunus necrotic ringspot virus (PNRSV) was isolated from apple orchards in the vicinity of Nubaria city, Beheira governorate, Egypt. Infected-apple trees showed chlorotic, necrotic ringspots, and shoot holes on leaves. Severely infected- trees withered, became useless, and were removed causing severe economic losses. Reverse transcriptase (RT) polymerase chain reaction (PCR), RT-PCR, using degenerate primer pair for the coat protein (CP) gene of Ilarvirus amplified products similar to those produced from peach and apricot isolates of PNRSV-infecting stone fruits). Dot blotting immuno-binding assay (DBIA showed a positive reaction between PNRSV-infected apple sap and an Egyptian antiserum for PNRSV. Purified preparation from infected leaves, using the electro-elution technique yielded nucleoprotein, which had Amax and Amin at 260 and 240 nm respectively. Electron microscopy examination showed spherical virions with ca. 26 nm in diameter.

Incidence and Molecular Identification of Apple Necrotic Mosaic Virus (ApNMV) in Southwest China

Apple mosaic disease has a great influence on apple production. In this study, an investigation into the incidence of apple mosaic disease in southwest China was performed, and the pathogen associated with the disease was detected. The results show that 2869 apple trees with mosaic disease were found in the Sichuan, Yunnan, and Guizhou Provinces, with an average incidence of 9.6%. Although apple mosaic virus (ApMV) is widespread in apples worldwide, the diseased samples were negative when tested for ApMV. However, a novel ilarvirus (apple necrotic mosaic virus, ApNMV) was identified in mosaic apple leaves which tested negative for ApMV. RT-PCR analysis indicated that ApNMV was detected in 322 out of 357 samples with mosaic symptoms. Phylogenetic analysis of coat protein (CP) sequences of ApNMV isolates suggested that, compared with ApMV, ApNMV was closer to prunus necrotic ringspot virus (PNRSV). The CP sequences of the isolates showed the diversity of ApNMV, which may enable the virus to adapt to the changeable environments. In addition, the pathology of mosaic disease was observed by microscope, and the result showed that the arrangement of the tissue and the shape of the cell, including the organelle, were seriously destroyed or drastically changed.