Virus da peste suina africana Caracterizacao de extremo esquerdo do genoma e efeito da infeccao viral na expressao de genes celulares

African swine fever virus (ASFV) is a relatively little studied virus due to the difficulties inherent to work with a virus capable of causing extensive epizootics and serious economic losses. Besides the obvious practical interest of studying the molecular biology of the virus, it is also an interesting biological model for the study of such important processes as transcription, DNA replication, and the regulation of gene expression in eukaryotes. In the Introduction, the biology of ASFV is reviewed with special reference to the more recent data on the molecular biology of the virus. The work presented in this thesis is intended as a contribution to a better understanding of the regulation of ASFV gene expression. Clones from the left DNA end of the Vero cell adapter Lisbon 60 strain (LIS60V) of ASFV were obtained from a genomic library of Hind III fragments cloned is plasmid pBluescript II SK"+. These clones were used to construct detailed restriction maps of the left 60 kb of the genome using seven restriction enzymes. Comparison with the BA71V strain, also Vero cell adapted and the best studied ASFV strain, revealed considerable variation in the genome organisation of the two strains and the existence of a unique region of about 9 kb in the left end of the LIS60V with no homology in the BA71V strain. Seven clones spanning approximately 24 kb were used to study transcription patterns from the left end of the genome by Northern blot analysis of RNAs extracted from ASFV infected cells at different times after infection and in cells treated with cycloheximide and cytosine arabinoside. Transcripts could be classified in distinct kinetic classes. No specifically early or late transcription regions were detected in the studied zone. The majority of the early transcripts continued to be present late in infection. For the first time the existence of delayed early transcripts is reported in ASFV infection. The expression of cellular genes, namely actin and ubiquitin, was studied in ASFV infected cells, revealing a complex expression pattern which appears to be differentially modulated by infection..Available from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1200 Lisboa / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga