Banca de DEFESA: MÁRCIA DANIELLE DE ARAÚJO DANTAS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MÁRCIA DANIELLE DE ARAÚJO DANTAS
DATA : 15/03/2019
HORA: 14:00
LOCAL: Sala Carl Peter von Dietrich - Departamento de Bioquímica
TÍTULO:

Study of the Genomes of Major Viruses Affecting Shrimp Farming in Brazil

PALAVRAS-CHAVES:

IMNV, WSSV, PstDNV, Phylogeny, Shrimp

PÁGINAS: 106
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
RESUMO:

The 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 study the IMNV, WSSV and PstDNV genomes and to contribute with new information on the biology of these pathogens. Chapter 1 describes the sequences study of the Totiviridae family members. 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 (hrs). Identity and phylogenetic analyzes have shown that Brazilian WSSV 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 discusses about the sequencing and analysis of a possible new Brazilian variant of PstDNV (PstDNV-BR17), which does not cause symptoms in shrimps in field. The identity comparison and phylogenetic analysis showed that the new isolate was part of the PstDNV infectious lineage, which was unexpected. Secondary and tertiary structure analyzes of viral proteins also did not show differences among Brazilian isolates. However, results of the 5'UTR region analysisrevealed peculiarities that suggest that this region may be involved in the PstDNV virulence mechanisms, which would explain the difference observed in the field. All these results together contribute to increase the knowledge about the main viruses that affect the global shrimp farming.

MEMBROS DA BANCA:
Presidente - 1880243 - DANIEL CARLOS FERREIRA LANZA
Interno - 2275890 - MARCELO DE SOUSA DA SILVA
Interna - 1674709 - VIVIANE SOUZA DO AMARAL
Externo à Instituição - RANIERE FAGUNDES DE MELO SILVEIRA - F.M.Nassau
Externo à Instituição - RUBENS GALDINO FEIJÓ - IFCE