The var3 genes of Plasmodium falciparum 3D7 strain are differentially expressed in infected erythrocytes

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is an important virulence factor encoded by a family of 59 var genes, including 56 var genes plus 3 small var3 genes. The var genes are among the most diverse sequences in the P. falciparum genome, but the var3 genes are found conserved in most P. falciparum strains. Previous studies have been mainly focused on the typical var genes, while the biological characteristics of the var3 genes remain unknown. In this study, the three var3 genes, PF3D7_0100300, PF3D7_0600400, and PF3D7_0937600, were found to be transcribed in the erythrocytic stages of P. falciparum, with a peak in the transcription level at 16 h post-invasion, but terminated immediately after 16 h post-invasion. The encoded protein of PF3D7_0600400 could be detected in both the late trophozoite stage and schizont stage, while the encoded proteins of PF3D7_0100300 and PF3D7_0937600 could only be detected in the late trophozoite stage and schizont stage, respectively. Thus, the var3 genes of the P. falciparum 3D7 strain were differentially expressed during the erythrocytic development of the parasite.