Immunoprecipitation with late-stage P. yoelii 17XL parasites and culture supernatants labeled in vitro for 6 h. (A) Immunoprecipitations with [35S]methionine-cysteine-labeled P. yoelii 17XL antigen. Lane 1, normal mouse serum; lane 2, mouse anti-P. yoelii MSP-7; lane 3, mouse anti-P. yoelii MSRP-2. (B) Immunoprecipitations with 35S-labeled culture supernatant. Lane 1, normal mouse serum; lane 2, mouse anti-P. yoelii MSP-7; lane 3, mouse anti-P. yoelii MSRP-2. All samples were preabsorbed with preimmune serum and exposed to film for 4 weeks.