Contribution of molecular biology to the improvement of insect viruses as biological control products.

A biologia molecular desempenha um importante papel na compreensao das propriedades biologicas dos virus de insetos utilizados no controle biologico de insetos-praga. A biologia molecular pode, tambem, ser utilizada para melhorar ou manter a eficacia dos produtos utilizados no controle biologico de insetos. Existem descricoes de 300 a 500 baculovirus de varias familias de insetos mas a maioria pertence a Lepidoptera. Poucos destes virus tem sido utilizados como produtos de controle biologico. O uso de enzimas de restricao para caracterizar o genoma dos baculovirus tem permitido desenvolver um metodo preciso para a identificacao destes diferentes virus. Uma vez identificados, qualquer virus contaminante pode ser detectado nas preparacoes. Estes virus podem ser melhorados expandindo tanto sua gama de hospedeiros como sua virulencia atraves de recombinacao genetica. Os eventos de recombinacao podem ser gerados e detectados por metodologias moleculares. Tecnicas de DNA recombinante podem tambem ser utilizadas para modificar os baculovirus de maneira que estes passem a produzir toxinas bacterianas ou outras toxinas que afetam insetos. Estes baculovirus poderiam matar seus insetos-alvo de maneira mais rapida. Metodos de biologia molecular sao essenciais para a analise de qualidade e identificacao de problemas associados com a producao dos virus de insetos nos quais baculovirus sao gerados com insercoes de DNA do inseto. Estes transposons de DNA levam o virus mutante a produzir poucos poliedros. Alem disso, genomas virais defeituosos sao gerados quando os baculovirus sao produzidos em sistemas continuos de cultura. Biologia molecular e utilizada para detectar estes defeitos e possivelmente seja usada para corrigi-los.Made available in DSpace on 2011-04-09T12:15:13Z (GMT). No. of bitstreams: 1 pab13abresp92.pdf: 1010866 bytes, checksum: 730bd27bf2495ef9da2415b5be168130 (MD5) Previous issue date: 2001-08-27199

Two viruses that cause salivary gland hypertrophy in Glossina pallidipes and Musca domestica are closely related and form a distinct phylogenetic clade

Glossina pallidipes and Musca domestica salivary gland hypertrophy viruses (GpSGHV and MdSGHV) replicate in the nucleus of salivary gland cells causing distinct tissue hypertrophy and reduction of host fertility. They share general characteristics with the non-occluded insect nudiviruses, such as being insect-pathogenic, having enveloped, rod-shaped virions, and large circular double-stranded DNA genomes. MdSGHV measures 65x550 nm and contains a 124 279 bp genome (44 mol% G+C content) that codes for 108 putative open reading frames (ORFs). GpSGHV, measuring 50x1000 nm, contains a 190 032 bp genome (28 mol% G+C content) with 160 putative ORFs. Comparative genomic analysis demonstrates that 37 MdSGHV ORFs have homology to 42 GpSGHV ORFs, as some MdSGHV ORFs have homology to two different GpSGHV ORFs. Nine genes with known functions (dnapol, ts, pif-1, pif-2, pif-3, mmp, p74, odv-e66 and helicase-2), a homologue of the conserved baculovirus gene Ac81 and at least 13 virion proteins are present in both SGHVs. The amino acid identity ranged from 19 to 39 % among ORFs. An (A/T/G)TAAG motif, similar to the baculovirus late promoter motif, was enriched 100 bp upstream of the ORF transcription initiation sites of both viruses. Six and seven putative microRNA sequences were found in MdSGHV and GpSGHV genomes, respectively. There was genome. Collinearity between the two SGHVs, but not between the SGHVs and the nudiviruses. Phylogenetic analysis of conserved genes clustered both SGHVs in a single clade separated from the nudiviruses and baculoviruses. Although MdSGHV and GpSGHV are different viruses, their pathology, host range and genome composition indicate that they are relate