O papel das nucleases no laboratório de biologia molecular: vilãs ou aliadas? / The role of nucleases in the molecular biology laboratory: villains or allies?

Em laboratório de biologia molecular existem normas para prevenir que nucleases destruam os ácidos nucleicos em análise. Rígida adesão a estas normas é primordial, principalmente em laboratórios de análises clínicas e ao se lidar com amostras com número restrito de cópias do genoma-alvo. Em contraposição, diversas nucleases têm tido importância fundamental, por exemplo, na identificação do ácido nucleico de vírus, investigação de RNA mensageiro, purificação de vírus em abordagem metagenômica, edição de genomas com o sistema CRISPR/Cas e descoberta de enzimas. O conhecimento de como nucleases podem ser tanto vilãs quanto aliadas é essencial na formação de todos que trabalham no campo de biologia molecular.

In a molecular biology laboratory there are standards to prevent nucleases from destroying the nucleic acids under analysis. Strict adherence to these standards is paramount, mainly in clinical analysis laboratories and when dealing with samples with a limited number of copies of the target genome. In contrast, several nucleases have been of fundamental importance, for example, in the identification of the type of viral nucleic acid, investigation of messenger RNA, virus purification in metagenomic approach, genome editing with the CRISPR/Cas system, and enzyme discovery. Knowledge of how nucleases can be both villains and allies is essential in the training of all working in the field of molecular biology.

O papel das nucleases no laboratório de biologia molecular: vilãs ou aliadas? / The role of nucleases in the molecular biology laboratory: villains or allies?

Em laboratório de biologia molecular existem normas para prevenir que nucleases destruam os ácidos nucleicos em análise. Rígida adesão a estas normas é primordial, principalmente em laboratórios de análises clínicas e ao se lidar com amostras com número restrito de cópias do genoma-alvo. Em contraposição, diversas nucleases têm tido importância fundamental, por exemplo, na identificação do ácido nucleico de vírus, investigação de RNA mensageiro, purificação de vírus em abordagem metagenômica, edição de genomas com o sistema CRISPR/Cas e descoberta de enzimas. O conhecimento de como nucleases podem ser tanto vilãs quanto aliadas é essencial na formação de todos que trabalham no campo de biologia molecular.

In a molecular biology laboratory there are standards to prevent nucleases from destroying the nucleic acids under analysis. Strict adherence to these standards is paramount, mainly in clinical analysis laboratories and when dealing with samples with a limited number of copies of the target genome. In contrast, several nucleases have been of fundamental importance, for example, in the identification of the type of viral nucleic acid, investigation of messenger RNA, virus purification in metagenomic approach, genome editing with the CRISPR/Cas system, and enzyme discovery. Knowledge of how nucleases can be both villains and allies is essential in the training of all working in the field of molecular biology.

Identification of circo-like virus-Brazil genomic sequences in raw sewage from the metropolitan area of São Paulo: evidence of circulation two and three years after the first detection

BACKGROUND Two novel viruses named circo-like virus-Brazil (CLV-BR) hs1 and hs2 were previously discovered in a Brazilian human fecal sample through metagenomics. CLV-BR hs1 and hs2 possess a small circular DNA genome encoding a replication initiator protein (Rep), and the two genomes exhibit 92% nucleotide identity with each other. Phylogenetic analysis based on the Rep protein showed that CLV-BRs do not cluster with circoviruses, nanoviruses, geminiviruses or cycloviruses. OBJECTIVE The aim of this study was to search for CLV-BR genomes in sewage and reclaimed water samples from the metropolitan area of São Paulo, Brazil, to verify whether the first detection of these viruses was an isolated finding. METHODS Sewage and reclaimed water samples collected concomitantly during the years 2005-2006 were purified and concentrated using methodologies designed for the study of viruses. A total of 177 treated reclaimed water samples were grouped into five pools, as were 177 treated raw sewage samples. Nucleic acid extraction, polymerase chain reaction (PCR) amplification and Sanger sequencing were then performed.e FINDINGS CLV-BR genomes were detected in two pools of sewage samples, p6 and p9. Approximately 28% and 51% of the CLV-BR genome was amplified from p6 and p9, respectively, including 76% of the Rep gene. The detected genomes are most likely related to CLV-BR hs1. Comparative analysis showed several synonymous substitutions within Rep-encoding sequences, suggesting purifying selection for this gene, as has been observed for other eukaryotic circular Rep-encoding single-stranded DNA (CRESS-DNA) viruses. MAIN CONCLUSION The results therefore indicated that CLV-BR has continued to circulate in Brazil two and three years after first being detected.

Molecular characterization of two rocio flavivirus strains isolated during the encephalitis epidemic in são paulo state, brazil and the development of a one-step rt-pcr assay for diagnosis

Rocio virus (ROCV) was responsible for an explosive encephalitis epidemic in the 1970s affecting about 1,000 residents of 20 coastland counties in São Paulo State, Brazil. ROCV was first isolated in 1975 from the cerebellum of a fatal human case of encephalitis. Clinical manifestations of the illness are similar to those described for St. Louis encephalitis. ROCV shows intense antigenic cross-reactivity with Japanese encephalitis complex (JEC) viruses, particularly with Ilheus (ILHV), St. Louis encephalitis, Murray Valley and West Nile viruses. In this study, we report a specific RT-PCR assay for ROCV diagnosis and the molecular characterization of the SPAn37630 and SPH37623 strains. Partial nucleotide sequences of NS5 and E genes determined from both strains were used in phylogenetic analysis. The results indicated that these strains are closely related to JEC viruses, but forming a distinct subclade together with ILHV, in accordance with results recently reported by Medeiros et al. (2007).

O vírus Rocio (ROCV) foi responsável por uma explosiva epidemia de encefalite que ocorreu nos anos 70 afetando cerca de 1.000 habitantes de 20 municípios litorâneos do Estado de São Paulo, Brasil. ROCV foi isolado em 1975 de cerebelo de caso humano fatal de encefalite. As manifestações clínicas da doença são semelhantes àquelas descritas para encefalite St. Louis. ROCV apresenta intensa reatividade cruzada com os vírus do Complexo da Encefalite Japonesa (JEV), particularmente com o vírus Ilhéus (ILHV) e com os vírus das encefalites St. Louis, Murray Valley e West Nile. Neste estudo, relatamos o desenvolvimento de um teste de RT-PCR específico para diagnóstico de ROCV e a caracterização molecular das cepas SPAn37630 e SPH37623. Foi realizada a análise filogenética das seqüências parciais dos genes NS5 e E, de ambas as cepas. Os resultados indicaram que essas cepas são intimamente relacionadas ao complexo JEV, mas formando um subgrupo com o ILHV, de acordo com os resultados recentemente publicados por MEDEIROS et al. (2007).

An exanthematic disease epidemic associated with coxsackievirus B3 infection in a day care center

E descrita uma epidemia de doenca exantematica em uma creche, acometendo 10 criancas de 7 a 13 meses de idade. O quadro exantematico caracterizou-se por lesoes maculo ou maculopapulares nao confluentes, que atingiam a face, tronco e pernas. 50 por cento das criancas infectadas apresentaram febre de ate 39 graus C, no inicio da doenca. Foi isolado das fezes de uma crianca doente o coxsackievirus B3 (CB3). Foram examinados soros pareados de 8 das 10 criancas doentes e em 6 delas demonstrou-se soroconversao para CB3...