Lanza, Daniel Carlos FerreiraDantas, Márcia Danielle de Araújo2019-07-232019-07-232019-03-15DANTAS, Márcia Danielle de Araújo. Estudo dos genomas dos principais vírus que acometem a carcinicultura no Brasil. 2019. 132f. Tese (Doutorado em Bioquímica) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2019.https://repositorio.ufrn.br/jspui/handle/123456789/27379The Northeast region is one of the largest shrimp producers in Brazil, with emphasis on the states of Rio Grande do Norte and Ceará. One of the biggest problems that the shrimp industry has faced in the last decades is the increase in the infectious diseases incidence, which cause great economic losses for the sector. Among these diseases, the most common are those caused by white spot syndrome virus (WSSV), Penaeus stylirostris densovirus (PstDNV) and infectious myonecrosis virus (IMNV). The genome study of these viruses is of fundamental importance to understand mechanisms essential to their survival and, thus, to develop effective tools for detection and control. In this context, the general objective of this work was to characterize the genomes of IMNV, WSSV and PstDNV variants, contributing with new information about the genome characteristics and taxonomy of these pathogens. Chapter 1 describes the sequences study of the Totiviridae family members. The results show that the IMNV and other family viruses that infect arthropods have characteristics that classify them into a new group preliminarily called Artivirus. The amino acid alignment of ORF1 indicates that the artiviruses are the only members of the Totiviridae family that have the 2A-like cleavage sites and two proteins previously predicted for the IMNV. A possible cleavage site upstream to the capsid protein has also been identified in these genomes. Protein models revealed conserved structures for the two proteins, indicating that they are probably involved in the formation of viral protrusions and RNA packaging. Chapter 2 addresses the sequencing and analysis of the genome of a Brazilian WSSV isolate (WSSV-BR). The genome was sequenced using the Ion Torrent platform and assembled using an alternate pipeline in which a WSSV chimera genome was used as the reference sequence. The genome had a size of 292.912 bp, 184 possible ORFs and nine homologous regions. Identity and phylogenetic analyzes have shown that WSSV-BR is closer to isolates from Thailand and Mexico and that probably these three viruses share a common evolutionary origin. In addition, it has been noted that the WSSV evolutionary history may be related to recombination events and that these events, somehow, can be traced by analyzing the homologous regions of WSSV. Chapter 3 provides the sequencing and genome analysis of a new Brazilian PstDNV isolate (PstDNV-BR17). The identity and phylogeny comparison showed that the new isolate is part of a PstDNV infectious lineage. Genetic variability analyzes have shown that there are few polymorphic sites between Brazilian isolates and that these changes do not affect the protein structure. Investigation of the 5'UTR region revealed the presence of a deletion in PstDNV-BR17 that alters secondary structures present in this region, which are important for viral replication. The information obtained from the study of the genomes could be used to subsidize the orientation of effective management and control measures to combat problems caused by viruses that affect shrimp farming.Acesso AbertoIMNVWSSVPstDNVFilogeniaCamarãodoctoralThesisCNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA