Table 1.

Immunization with Δpcrmp3 or Δpcrmp4 sporozoites does not protect Balb/c or C57BL/6 mice against subsequent challenge with WT sporozoites

	Δpcrmp3 or Δpcrmp4 sporozoites			WT	#protected/# challenged
Mouse Strain	Immunization	Boost I	Boost II	Sporozoite Challenge	Control	Δpbcrmp3	Δpbcrmp4
Balb/c	50 000	-	-	10 000	0/6 (0)	0/6 (0)	0/6 (0)
C57Bl/6	50 000	20 000	20 000	10 000	0/6 (0)	0/6 (0)	0/6 (0)

Groups of mice were immunized i.v. with 50,000 Δpcrmp3 or Δpcrmp4 sporozoites isolated from several mosquitoes. Boosts were performed with 20,000 sporozoites at weekly intervals. Mice were challenged with 10,000 WT sporozoites 10 days after immunization (Balb/c) or second boost (C57BL/6), and infections were monitored by counting of giemsa-stained blood smears. All mice became positive on day 4 after challenge.