Fig. 1.

A. Cysteine and serine protease inhibitors block detachment of P. berghei-infected HepG2 cells. HepG2 cells were infected with P. berghei sporozoites. Upon cultivation for 48 h, cells were treated with 100 μM of either antipain or leupeptin for an additional 13 h. Detached cells in treated and untreated control wells were counted and expressed as a percentage of control (untreated) cells. Error bars have been calculated from data of three independent experiments.

B. The SERA gene family of P. berghei consists of five members, aligned in a tandem cluster. Dark grey boxes represent exons of the ‘cysteine-type’ SERA members, light grey boxes symbolize the exons of ‘serine-type’ SERAs.

C. PbSERA1–4 expression is upregulated in late liver stages. HepG2 cells were infected with P. berghei sporozoites and mRNA of these infected cells was prepared at 24, 38, 50 and 62 h post infection. Messenger RNA expression of all five PbSERAs was verified by RT-PCR. As a control, tubulin mRNA was additionally amplified.

D. PbSERA mRNA expression is stage specifically regulated. mRNA expression of all five PbSERAs was verified by RT-PCR. Total mRNA was isolated from two mosquito stages (oocysts and salivary gland sporozoites), and from three parasite stages of the vertebrate host (late liver schizont stage, detached cells/merosomes and the blood stages) and subjected to RT-PCR analysis.