Figure 2.

Structure of the T-DNA region of pHB114, the vector used for expression of HBsAg. The small HBsAg gene is inserted into an expression cassette from which transcription is driven by the cauliflower mosaic virus 35S promoter. The tobacco etch virus 5′-UTR provides enhancement of translation, and the Pin2 3′ element mediates polyadenylation. The selectable marker for plant transformation is the Npt2 gene, which confers resistance to kanamycin. LB and RB indicate the left and right borders of the T-DNA region, which, during Agrobacterium-mediated DNA delivery, become stably integrated into nuclear chromosomal DNA.