gDNA-seq of 7G8 subclones with different var expression patterns
The parasite Plasmodium falciparum is responsible for severe malaria, which remains a major cause of death, particularly in sub-Saharan Africa. The reference strain NF54 (or its subclone 3D7) is commonly used for controlled human malaria infection (CHMI), but recently strains with a different geographic and genomic background have become available for CHMI, including 7G8, which was subcloned from the Brazilian isolate IMTM22 in 1984 (Burkot TR et al. 1984. Infectivity to mosquitoes of Plasmodium falciparum clones grown in vitro from the same isolate. Trans R Soc Trop Med Hyg 78 (3):339-41. doi: 10.1016/0035-9203(84)90114-7). In contrast to NF54, in which var gene expression resets after mosquito transmission, 7G8 shows a partial reset with retention of the C-type var gene PF7G8_040025600 in the human host.  The three subclones A1G9 (almost exclusive var2csa expression, control), A2E10, and A2G2 (both predominantly expressing var gene PF7G8_040025600) recently obtained by limited dilution from the Sanaria 7G8 parasite working cell bank (Lot: SAN03-021214 dated 20. February 2014) were selected for gDNA sequencing to test whether parasite subclones expressing PF7G8_040025600 differ in their genomic background. 150 mL of P. falciparum cell culture with >10% parasitemia was harvested and gDNA isolation was performed using the MasterPure™ Complete DNA Purification Kit (Lucigen). The gDNA samples were tested for degradation and RNA contamination on an agarose gel and quantified using the Qubit™ dsDNA BR Assay Kit (ThermoFischer). DNA-seq was performed at BGI Genomics (Shenzhen, China) on the DNBseq platform to generate 150 bp paired-end sequencing reads.