Following the immunization, mice were challenged with bites from 15 P. yoelii-infected mosquitoes (on day 28), and the parasite liver-stage infection biomass was assessed by P. yoelii-specific 18S reverse transcriptase quantitative PCR (RT-qPCR) relative to the control group immunized with the HIV-1 Env gp120 subunit. The gene discussed is ERVW-1; the disease is infection.