RESUMO
Tomato yellow ring virus (TYRV), first isolated from tomato in Iran, was classified as a non-approved species of the genus Tospovirus based on the characterization of its genomic S RNA. In the current study, the complete sequences of the genomic L and M RNAs of TYRV were determined and analyzed. The L RNA has 8,877 nucleotides (nt) and codes in the viral complementary (vc) strand for the putative RNA-dependent RNA polymerase (RdRp) of 2,873 amino acids (aa) (331 kDa). The RdRp of TYRV shares the highest aa sequence identity (88.7 %) with that of Iris yellow spot virus (IYSV), and contains conserved motifs shared with those of the animal-infecting bunyaviruses. The M RNA contains 4,786 nt and codes in ambisense arrangement for the NSm protein of 308 aa (34.5 kDa) in viral sense, and the Gn/Gc glycoprotein precursor (GP) of 1,310 aa (128 kDa) in vc-sense. Phylogenetic analyses indicated that TYRV is closely clustered with IYSV and Polygonum ringspot virus (PolRSV). The NSm and GP of TYRV share the highest aa sequence identity with those of IYSV and PolRSV (89.9 and 80.2-86.5 %, respectively). Moreover, the GPs of TYRV, IYSV, and PolRSV share highly similar characteristics, among which an identical deduced N-terminal protease cleavage site that is distinct from all tospoviral GPs analyzed thus far. Taken together, the elucidation of the complete genome sequence and biological features of TYRV support a close ancestral relationship with IYSV and PolRSV.
Assuntos
RNA Viral/genética , Tospovirus/genética , Motivos de Aminoácidos , Animais , Análise por Conglomerados , Sequência Conservada , Glicoproteínas/genética , Irã (Geográfico) , Solanum lycopersicum , Dados de Sequência Molecular , Filogenia , RNA Polimerase Dependente de RNA/genética , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Tospovirus/isolamento & purificação , Proteínas não Estruturais Virais/genética , Proteínas Estruturais Virais/genéticaAssuntos
Citrullus/virologia , Tospovirus/genética , Sequência de Bases , Primers do DNA/genética , Genoma Viral , Índia , Dados de Sequência Molecular , Proteínas do Nucleocapsídeo/genética , Filogenia , Doenças das Plantas/virologia , RNA Viral/genética , Especificidade da Espécie , Tospovirus/classificação , Tospovirus/isolamento & purificação , Proteínas Virais/genéticaRESUMO
Melon yellow spot virus (MYSV), a tentative member of the genus Tospovirus, is considered a distinct serotype due to the lack of a serological relationship with other tospoviruses in its nucleocapsid protein (NP). Recently, a virus isolate collected from diseased watermelon in central Taiwan (MYSV-TW) was found to react with a rabbit antiserum (RAs) prepared against the NP of Watermelon silver mottle virus (WSMoV), and a monoclonal antibody (MAb) prepared against the common epitope of the NSs proteins of WSMoV-serogroup tospoviruses, but not with the WSMoV NP-specific MAb, in both enzyme-linked immunosorbent assay (ELISA) and western blotting. In this investigation, both RAs and MAb against MYSV-TW NP were produced. Results of serological tests revealed that the RAs to MYSV-TW NP reacted with the homologous antigen and the crude antigens of members of the WSMoV serogroup, including members of the formal species WSMoV and Peanut bud necrosis virus, and members of three tentative species, Watermelon bud necrosis virus, Capsicum chlorosis virus and Calla lily chlorotic spot virus. The MAb to MYSV-TW NP reacted only with the homologous antigen and the other geographic isolates of MYSV from Japan (JP) and Thailand (TH). Our results of reciprocal tests indicate that the NP and the NSs protein of MYSV are serologically related to those of WSMoV-serogroup tospoviruses. Furthermore, we show that both the MYSV NP MAb and the WSMoV NP MAb are reliable tools for identification of MYSV and WSMoV from single or mixed infection in field surveys, as verified using species-specific primers in reverse transcription-polymerase chain reaction.
