ABSTRACT
The genus Fabavirus of the family Secoviridae comprises a group of poorly characterized viruses. To date, only five species have been described: Broad bean wilt virus 1 (BBWV-1), Broad bean wilt virus 2 (BBWV-2), Lamium mild mosaic virus (LMMV), Gentian mosaic virus (GeMV) and Cucurbit mild mosaic virus (CuMMV). The development is described of two RT-PCR procedures for the detection and identification of Fabavirus species: a one-step RT-PCR using a single pair of conserved primers for the detection of all fabaviruses, and a one-step multiplex RT-PCR using species-specific primers for the simultaneous detection and identification of the above-mentioned species of the genus Fabavirus. These methods were applied successfully to field samples and the results were compared with those obtained by molecular hybridization and ELISA. The combination of the two techniques enables rapid, sensitive and reliable identification of the five known fabavirus species, as well as the possibility of discovering new species of this genus.
Subject(s)
Fabavirus/classification , Fabavirus/isolation & purification , Reverse Transcriptase Polymerase Chain Reaction/methods , DNA Primers/genetics , Fabavirus/genetics , Plant Diseases/virology , RNA, Viral/genetics , Sensitivity and Specificity , Time FactorsABSTRACT
Lamium mild mosaic virus (LMMV) is the only one of the five members of the genus Fabavirus for which there are no nucleotide sequence data. In this study, the complete genome sequence of LMMV was determined and compared with the available complete genome sequences of other members of the genus Fabavirus. The genome was the largest of the genus but maintained the typical organization, with RNA 1 of 6080 nucleotides (nt), RNA 2 of 4065 nt, and an unusually long 3' untranslated region in RNA 2 of 603 nt. Phylogenetic analysis of the amino acid sequences of the protease-polymerase (Pro-Pol) region and the two coat proteins confirmed that LMMV belongs to a distinct species within the genus Fabavirus.
Subject(s)
Fabavirus/genetics , Genome, Viral/genetics , Lamiaceae/virology , Mosaic Viruses/genetics , Plant Diseases/virology , Sequence Analysis, DNA , Base Sequence , Capsid Proteins/genetics , DNA-Directed RNA Polymerases/genetics , Fabavirus/classification , Fabavirus/physiology , Molecular Sequence Data , Mosaic Viruses/classification , Mosaic Viruses/physiology , Peptide Hydrolases/genetics , Phylogeny , RNA, Viral/genetics , Species Specificity , Nicotiana/virology , Viral Proteins/geneticsABSTRACT
The genetic variation and evolution of cucumber mosaic virus (CMV) from aromatic, medicinal and ornamental plants in northern Italy was studied by sequence analysis of the movement protein gene and comparison with equivalent sequences of isolates from other countries. Comparison of nonsynonymous and synonymous substitutions suggested that 30% of amino acid sites were under negative selection and only one was under positive selection. Phylogenetic, nucleotide diversity and genetic differentiation analyses suggested that long-distance migration plays a role in the evolution and determination of the genetic structure and diversity of CMV in northern Italy and other areas.
