Salmonella enterica serovar Typhi (S. Typhi) is a Gram-negative, intracellular, human pathogen that is the causative agent of typhoid fever, responsible for 200,000 deaths worldwide, per year. Central to S. enterica pathogenesis are two type III secretion systems (T3SS), that are used to translocate up to 40 effector proteins to enable invasion, replication and manipulation of host immune responses. These proteins have been largely characterised in other S. enterica serovars and many are pseudogenes or absent from the genome of S. Typhi. The identification of a putative effector protein in S. Typhi, StoD, a member of the NleG family of bacterial E3 ubiquitin-ligase effectors, suggested that there may be more effectors in S. Typhi, than previously thought. In this study, a containment level three laboratory was established to enable the study of S. Typhi pathogenesis, and the role of novel T3SS effector proteins in this. A genome-wide machine-learning approach was then used to identify five putative effectors in S. Typhi, four of which, as well as StoD, were experimentally validated as being T3SS effectors. Whilst none of these novel effectors were found to be required for S. Typhi invasion or replication, StoD, and another novel effector, StoE, were found to localise in a punctate fashion in HeLa cells. For StoE, this localisation was shown to be dependent on a N-terminal transmembrane domain, whilst StoD was found to colocalise with the eukaryotic protein, ubiquitin, involved in protein regulation and cellular signalling. This colocalisation was demonstrated to be dependent on the E3 ubiquitin-ligase activity of StoD and whilst it was not possible to identify any substrates of StoD, further biochemical characterisation found that StoD preferentially bound K63-linked, di-ubiquitin. These findings increase the known repertoire of S. Typhi T3SS effectors from 23 to 28 proteins and suggest that further effectors could be identified.