Some Properties of Hop Latent and Apple Mosaic Viruses Isolated from Hop Plants and Their Distributions in Japan

Abstract

This paper reports some properties of hop latent virus (HLV) and apple mosaic virus (ApMV) isolated from hop plants and the distributions of the viruses in hop gardens in Japan. HLV isolated in this study was 650 nm in length and 13 nm in width and had a single coat protein species with M_r 34, 700 daltons (Da) and a single nucleic acid species with M_r 2.98×10⁶ Da. In immunosorbent electron microscopy, the virus was trapped and decorated with antiserum against HLV from England, but not with antisera against hop mosaic virus or American hop latent virus. The spherical virus isolated in this study formed precipitation lines with antisera against ApMVs, but not with antisera against prunus necrotic ringspot virus and Humulus japonicus virus in double diffusion tests and was identified as ApMV. Purified ApMV contained isometric particles of 22 and 24 nm in diameter and some quasi-isometric particles of 24×26-28 nm, and comprised a single coat protein species with M_r 27, 500 Da and four nucleic acid species with M_r 1.39, 1.11, 0.72 and 0.34×10⁶ Da. Distributions of HLV and ApMV in commercial hop plants were investigated by DIBA and ELISA, respectively. HLV was detected in the hops collected from all of 21 hop gardens located in 5 prefectures and the incidence of infection was 75.2% (158/210). ApMV was detected in 37.2% (67/180) of hop plants in 14 out of 18 hop gardens.