RESUMO
We describe the genomic characteristics of a new potyvirus isolated from tobacco plants showing mottling ("mosqueado" in Portuguese) in southern Brazil. The complete genomic sequence consists of 9896 nucleotides, without the poly(A) tail, and shares the highest pairwise nucleotide sequence identities of 68.5 % with pepper yellow mosaic virus and 68.2 % with Brugmansia mosaic virus isolate D437. These identity values are below the level of 76.0 % used as a criterion for species demarcation in the genus Potyvirus based on the complete genome sequence. The viral genomic organization and sequence comparison thus suggest that this virus, tentatively named "tobacco mosqueado virus" (TMosqV), represents a new potyvirus species.
Assuntos
/virologia , Doenças das Plantas/virologia , Vírus de Plantas/genética , Potyvirus/genética , Potyvirus/isolamento & purificação , Sequência de Bases , Técnicas de Amplificação de Ácido Nucleico , Filogenia , RNA de Cadeia Dupla/genéticaRESUMO
Noroviruses (NVs) are responsible for most cases of human nonbacterial gastroenteritis worldwide. Some parameters for the purification of NV virus-like particles (VLPs) such as ease of production and yield were studied for future development of vaccines and diagnostic tools. In this study, VLPs were produced by the expression of the VP1 and VP2 gene cassette of the Brazilian NV isolate, and two purification methods were compared: cesium chloride (CsCl) gradient centrifugation and ion-exchange chromatography (IEC). IEC produced more and purer VLPs of NV compared to CsCl gradient centrifugation.
Assuntos
Centrifugação com Gradiente de Concentração/métodos , Cromatografia por Troca Iônica/métodos , Norovirus/genética , Proteínas Estruturais Virais/genética , Virossomos/isolamento & purificação , Brasil , Criança , Humanos , Proteínas Estruturais Virais/metabolismo , Virossomos/genética , Virossomos/metabolismoRESUMO
Abstract Noroviruses (NVs) are responsible for most cases of human nonbacterial gastroenteritis worldwide. Some parameters for the purification of NV virus-like particles (VLPs) such as ease of production and yield were studied for future development of vaccines and diagnostic tools. In this study, VLPs were produced by the expression of the VP1 and VP2 gene cassette of the Brazilian NV isolate, and two purification methods were compared: cesium chloride (CsCl) gradient centrifugation and ion-exchange chromatography (IEC). IEC produced more and purer VLPs of NV compared to CsCl gradient centrifugation.
Assuntos
Criança , Humanos , Centrifugação com Gradiente de Concentração/métodos , Cromatografia por Troca Iônica/métodos , Norovirus/genética , Proteínas Estruturais Virais/genética , Virossomos/isolamento & purificação , Brasil , Proteínas Estruturais Virais/metabolismo , Virossomos/genética , Virossomos/metabolismoRESUMO
Pepper ringspot virus (PepRSV) is a tobravirus reported only in Brazil. Here, the sequences of the complete RNA 2 segments and the 3' end of the RNA 1 genomic regions of two new isolates from tomato plants were analyzed. The main ORF encodes the CP gene as other tobraviruses and termed ORF 1 of RNA 2. The second ORF was found only in one of the new isolates, although this gene was absent in the type isolate, CAM (collected in the 1960's). Interestingly, this ORF 2 gene did not show any nucleotide and amino acid sequence similarities with known 2b genes of tobraviruses, an essential gene of tobraviruses for nematodes-transmission. The 5'UTR sequence of RNA 2 segment of CAM isolate was previously reported showing two impaired direct repeats; however, the direct-repeats were absent in these new isolates. An additional ORF was predicted upstream of the CP gene. This putative protein possessed a transmembrane domain similar to the ORFN1 of RNA 2 of Tobacco rattle virus SYM isolate, although there was no sequence similarity. This is the first report on the diversity of the RNA 2 sequences of PepRSV.
