Regulation of multiple infection in alphabaculoviruses: critical factors that determine success

Abstract

This thesis is focused in the ability of different baculovirus species to coinfect a particular host. I investigate whether the co-occlusion of different species is allowed and if it confers some advantage to the viruses, like the generation and maintenance of the viral heterogeneity in ecosystems where two or more virus species are present. Furthermore, as co-infection with different species implies sharing of host resources, we would like to explore the mechanisms (if any) regulating co-infection. Does a virus present in a given cell produce a signal that blocks other virus infection? Can this signal discriminate in function of the relatedness of the genomes? The existence of a temporal window that may allow coinfections and after which the organism becomes refractive to a second infection was analyzed, both in vivo and in vitro. This work also studies, in depth, the factors involved in the establishment of the block to infection by the second virus, such as temporal influences or cellular rearrangements. In a second part, the complete sequence of a Nicaraguan isolate of the SfMNPV is shown and compared with the sequences of this virus that had been previously published. In order to increase our understanding of the virus and its evolution and adaptation to its natural host, we studied the functionality of a unique gene present only in SfMNPV (sf32), some genes suggested to have a host-dependent function (sf68, sf95 and sf138) and a gene undergoing positive selection (sf122).