Table 1.
Features shared by P. knowlesi SICA and P. falciparum EMP1
| Variant antigen characteristic | SICA protein | PfEMP1 |
|---|---|---|
| Large parasite-encoded proteins | ✓ | ✓ |
| Exposed at infected RBC surface | ✓ | ✓ |
| Extractable only by ionic detergents | ✓ | ✓ |
| Undergo antigenic variation | ✓ | ✓ |
| Associated with virulence | ✓ | ✓ |
| Encoded by large multigene family | ✓ | ✓ |
| Contain cysteine-rich domains | ✓ | ✓ |
| Subject to much diversity | ✓ | ✓ |
| Genes on all chromosomes | ✓ | ✓ |
| In situ transcription | ✓ | ✓ |
| Abundant transcription in ring stage | ✓ | ✓ |
| Translation in trophozoite stage | ✓ | ✓ |
| Antisense long non-coding RNAs in gene regulation | ✓ | ✓ |
| Epigenetic gene control | ✓ | ✓ |
| Role for spleen in expression control | ✓ | ✓ |
| Associated with typical cytoadherence/sequestration | × a | ✓ |