Addition of histamine to subcutaneously injected Plasmodium berghei sporozoites increases the parasite liver load and could facilitate whole-parasite vaccination

Table 1 Protection after chloroquine chemoprophylaxis with sporozoites immunization

	Week	CQ control	CQ-CPS iv	CQ-CPS 100 μg sc	CQ-CPS sc
	Week	n = 4	n = 8	n = 8	n = 8
Immunization/drug treatment (prime; boost 1; boost 2)	0; 1; 2	- / CQ-DW	3 × 10³ SPZ iv / CQ-DW	3 × 10⁴ SPZ + 100 μg his and 5IU hep sc / CQ-DW	3 × 10⁴ SPZ sc / CQ-DW
Challenge	8	10⁴ SPZ iv	10⁴ SPZ iv	10⁴ SPZ iv	10⁴ SPZ iv
Animals protected		0/4	8/8	2/8	0/6*
Animals surviving by day 14 post-challenge		1/4	8/8	8/8	6/6

CQ-DW: chloroquine supplemented drinking water; his: histamine; hep: heparin.
CQ-DW was maintained in all animals from prime immunization until 2 weeks after the final boost immunization.
*two animals died during the immunization process for unknown reasons.

ISSN: 1475-2875