2. 6 Immunization with Scd KO sporozoites protects
against malaria
Immunizations with sporozoites that arrest in the liver elicit a
long-term protective host response and protect against infectious
sporozoite challenge (Duffy, 2022). To study preerythrocytic protection
induced by Scd KO parasites, groups of C57BL/6 mice were
intravenously injected with three doses of sporozoites at intervals of
two weeks and challenged with infectious sporozoites 10 days post-last
immunization. All immunized mice remained blood stage negative after
immunization, again demonstrating the lack of breakthrough blood stage
infection. We found that all the mice injected with uninfected salivary
gland debris developed blood-stage parasitemia, whereas mice immunized
with Scd KO sporozoites were completely protected (Table 3). We
further challenged the protected mice 120 days after the last
immunization, and they remained protected (Table 3). These results
demonstrate that immunization with Scd KO sporozoites induces
preerythrocytic immunity and protects against malaria.