Rhopalosiphum padi viras (RhPV) is one of several picorna-like viruses that infect insects; sequence analysis has revealed distinct differences between these agents and mammalian picornaviruses. RhPV has a single-stranded positive sense RNA genome of about 10kb; unlike the genomes of the Picornaviridae, however, this genome contains two long open reading frames (ORFs). ORF1 encodes the virus non- structural proteins, while ORF2 specifies the structural proteins. Both ORFs are preceeded by long untranslated regions (UTRs). The intergenic UTR is known to contain an internal ribosome entry site (IRES) that directs non-AUG-initiated, translation of ORF2. The 5' UTR of RhPV was assayed for IRES activity by translating synthetic bicistronic mRNAs containing this sequence in a variety of systems. The 5' UTR contains an IRES element that directs internal initiation of protein synthesis from an AUG codon in mammalian. Drosophila and plant in vitro systems and in vivo in an insect non-aphid cell line. In contrast, the encephalomyocarditis virus IRES only functions in mammalian in vitro and in vivo systems. The RhPV 5' IRES element has features in common with picornavirus IRES elements, in that no coding sequence is required for IRES function, but also with cellular IRES elements, as deletion analysis indicates that this IRES element does not have sharply defined boundaries. IRES activities of the 5' UTRs of other insect picorna-like viruses Acyrthosiphon pisum virus (APV) and the type 2 insect picorna-like virus Sacbrood viras (SBV) were also examined. Both viruses were shown to contain IRES elements that functioned in mammalian and plant in vitro systems and in vivo in an insect non-aphid cell line. Comparison of the IRES activities of RhPV with APV and SBV showed the RhPV 5' IRES element to be more efficient than both the APV and SBV IRES elements in mediating internal initiation of protein synthesis.

Submitted by Sandro Camargo (sandro.camargo@unipampa.edu.br) on 2015-05-07T22:43:52Z No. of bitstreams: 1 126110038.pdf: 2182930 bytes, checksum: 1d0e56324e775d985abbaf5cea8f4038 (MD5) / Made available in DSpace on 2015-05-07T22:43:52Z (GMT). No. of bitstreams: 1 126110038.pdf: 2182930 bytes, checksum: 1d0e56324e775d985abbaf5cea8f4038 (MD5) Previous issue date: 2014-03-21 / As abelhas apresentam uma combinação de características individuais e ainda de cooperação animal não encontrada no restante do reino animal. São insetos sociais e participam da polinização de diversas plantas que fornecem alimento para o homem. No Brasil com a africanização das abelhas, essas tornaram-se altamente produtoras e enxameadoras, o que vem tornando o país uma potência na produção de mel e outros produtos originados da atividade apícola. Muitas doenças podem afetar as abelhas, dentre elas muitas causadas por vírus. Controlar as infecções virais é essencial para a manutenção ecológica das abelhas e da produção apícola. Ao mesmo tempo, existe a possibilidade de relacionar vírus que infectam humanos com os vírus que infectam as abelhas, visto que os tratamentos utilizados para os seres humanos poderiam ser utilizados em colméias e, ao mesmo tempo, utilizar as abelhas como modelo de estudo para o desenvolvimento de novos antivirais. Na busca por um ponto em comum analisamos filogeneticamente a protease 3C, que ocorre nos vírus da super-família Picorna-like, onde encontram-se os vírus que parasitam as abelhas. Essa protease tem a capacidade de clivar a poliproteína viral nas proteínas maduras do vírus e ainda causar a degradação proteolítica das proteínas do hospedeiro. Até hoje não foi encontrada uma forma de utilizar a protease 3C em estudos filogenéticos pois existe muita divergência das suas sequências entre os vírus. O objetivo dessa pesquisa foi identificar uma forma de analisar filogeneticamente a protease 3C. As sequências da protease 3C e da RdRp de 55 vírus foram coletadas do NCBI ( National Center of Biotechnology Information) e submetidas ao MEME ( Multiple Em for Motif Elicitation), onde foram obtidos quatro sítios conservados. Após foi realizada a análise filogenética dos sítios conservados por Máxima Verossimilhança e análise da distância entre os sítios por parcimônia e ainda foi construída uma árvore com base na RdRp. As árvores dos sítios 1 e 2 apresentaram uma melhor robustez estatística e agrupamento dos vírus. Essas regiões conservadas da protease 3C-Pro podem ser o início para estabelecermos uma relação entre as proteases dos picornavírus e vírus picorna-like na busca da compreensão do seu mecanismo de infecção viral e também uma alternativa de estudo para outras sequências com alta variabilidade. O uso dos domínios 1 e 2 proporcionou a árvore com maior robustez apresentada até o dia de hoje para esta proteína viral. / The bees have a combination of individual features and animal cooperation is not yet found in the rest of the animal kingdom . They are social insects and participate in the pollination of many plants that provide food for man . In Brazil with the africanization of bees , these have become highly producing and swarm , which is making the country a power in the production of honey and other products derived from beekeeping . Many diseases can affect bees , among them many caused by viruses . Control viral infections is essential for ecological maintenance of bees and beekeeping . At the same time , it is possible to relate viruses that infect humans and viruses that infect the bees , whereas the treatments for humans could be used in beehives and at the same time using the bees as a model for development of new antiviral agents. In the search for a common point analyzed phylogenetically 3C protease , which occurs in the superfamily Picorna -like, which are viruses that parasitize bees virus. This protease is capable of cleaving the polyprotein, the mature viral proteins and viruses also cause the proteolytic degradation of host proteins . Until today there a way to use the 3C protease was found in phylogenetic studies because there is much divergence of their sequences between virus.The objective of this research was to identify a way to analyze phylogenetically 3C protease . The 3C protease and RdRp sequences of 55 viruses were collected from the National Center for Biotechnology Information , submitted to MEME , where four conserved sites were obtained . Upon phylogenetic analysis of the conserved sites and by maximum likelihood analysis of the distance between sites by parsimony was performed and was still a tree constructed based on the RdRp . Trees of sites 1 and 2 had a better statistical robustness and clustering of virus. These conserved regions of the 3C protease - Pro may be the start to establish a relationship between the proteases of the picornavirus and Picorna-like viruses in the quest to understand the mechanism of viral infection and also an alternative study for other sequences with high variability . The use of domains 1 and 2 provided the tree with greater robustness displayed until today for this viral protein.