Some Physicochemical Properties of Maize Rayado Fino Virus

Abstract

67 SUMMARYMaize rayado fino virus (RFV) was purified from infected maize (Zea mays) leaves. The virus had two components: empty shells and complete virus particles with sedimentation coefficients of 54S and 120S respectively, and buoyant densities of 1.28 and 1.46 g/ml in CsC1 and 1.24 and 1.37 g/ml in Cs2SO4. Virus particles were stable from pH 7 to pH 4 but not at pH 3. Isoelectric focusing of purified empty capsids revealed a single band in the pH range of 6 to 6.2. RFV contained 33 to 36% of single-stranded (ss)RNA of mol. wt. approx. 2 × 106. Dissociated coat protein migrated in acrylamide gel electrophoresis as a main band with an average mol. wt. of 2.1 x 104. RFV shares several biological and physicochemical properties with oat blue dwarf virus. These viruses appear to represent a new group of small RNA viruses, transmitted propagatively by their cicadellid vectors.

The Two Capsid Proteins of Maize Rayado Fino Virus Contain Common Peptide Sequences

“…Maize (Zea mays L.) is the economically important plant host, and the corn leafhopper (Dalbulus maidis Delong & Wolcott) serves as both a host and the major vector of MRFV [3,4], Recently, Central American (MRFV-CA) and North American (MRFV-TX) isolates of MRFV have been purified and partially characterized by two laboratories [1,2]. MRFV-TX was found to have two prominent capsid proteins [1] whereas MRFV-CA was believed to have one major capsid protein and possibly a minor protein [2]. We investi gated the properties of a Florida MRFV iso late and report here that limited proteolytic cleavage of the two capsid proteins yields an indistinguishable set of polypeptides when analyzed by one-dimensional SDS-PAGE.…”

“…Maize rayado fino virus (MRFV) is a virus with small isometric particles and a singlestranded RNA genome [1,2]. Its host range includes both plants and insects [3,4].…”

“…Virions and empty capsids (top component) were puri fied using a modification of methods used previously for other MRFV isolates [1,2], In specified experiments the buffer was supple mented with the protease inhibitors iodoacetate (15 mM) or phenylmethylsulfonylfluoride (2 mM). Tissues were chopped with a razor blade and homogenized with 4 vol (w/v) of buffer (0.1 M potassium phosphate (pH 7.0) containing 0.1% 2-mercaptoethanol] in a Waring blender.…”

Multiplication of Maize Rayado Fino Virus in the Leafhopper Vector <i>Dalbulus maidis</i>

“…Such ability ap peared at first to be associated only with viruses containing relatively large genomes [2], More recently, two viruses with small single-stranded RNA genomes, oat blue dwarf virus [3,4] and maize rayado fino virus (MRFV) [5][6][7], have been shown to multiply in their leafhopper vectors, and are consid ered to represent a new group of plant viruses [2,8,9],…”

Electron Microscopy of Maize Rayado Fino Virus in the Internal Organs of Its Leaf hopper Vector

“…Evidence of virus replication in the insect's body was obtained by enzymelinked immunosorbent assay (ELISA) [3][4][5], Oat blue dwarf virus (OBDV) [6] and RFV share several biological and physicochemical properties and are considered to represent a new group of viruses with propagative cycles in plants and insects [7], These virus particles are much smaller than those of reo-and rhabdoviruses, the only two groups of plant viruses previously shown to multiply in their insect vectors.…”