Dengue virus poses a significant health threat. The new emerging strains continue to cause annual epidemics. In this paper, we report results of an analysis of dengue virus serotype 1 (DV1) genome polyprotein sequences in the context of time and geographical distribution. We studied the clustering of 60 DV1 genome polyprotein sequences of different geographical distributions, reported in the past 30 years, to identify geographic and temporal patterns of genetic and antigenic variation. Our analysis showed distinct clustering of sequences into two main geographical regions: i) Western and South Pacific and South-East Asian region (with three distinct sub-clusters) and ii) South American region. The results provide evidence suggesting temporal changes of the isolated strains. In addition, our analysis indicated that potential T-cell epitope hotspots within DV1 are shifting with time and recurrent epidemics, resulting in disappearing of some hotspots and emerging of new hotspots.