Western immunoblotting of proteins from FD phytoplasma-infected
transformants. The blots were probed with a 1:400 dilution of anti-VmpA rabbit serum. A lanes 1, FD phytoplasma-infected E. variegatus; 2–7, S. citri transformed by pSTP2 (empty vector), pSTVA3–6 [vmpAp inserted in sense (pSTVA3 and pSTVA5) and antisense (pSTVA4 and pSTVA6) orientations at two distinct positions (see Additional file 2: Figure S2)], and pSTVA1 (vmpAs), respectively; 8–10, E. coli transformed by pBPTS1 (empty vector), and pBVA3–4 (vmpAp), respectively. Each well was loaded with 100 μg of total proteins in the case of S. citri transformants and 20 μg for E. coli. B lanes 1–2, S. citri transformed by pSTVA1 (vmpAs) and pSTVA5 (vmpAp), respectively; 3 and 5, FD phytoplasma-infected E. variegatus; 4, E. coli transformed by pSTVA3 (vmpAp). Apparent molecular masses of the various VmpA-specific polypeptides are indicated in bold characters.