title: Reinforcement of immunity in Saimiri monkeys following immunization with irradiated sporozoites of Plasmodium vivax.
abstract: To determine the duration of immunity to Plasmodium vivax following immunization, six Saimiri sciureus boliviensis monkeys were vaccinated with irradiated sporozoites of P. vivax and challenged multiple times with sporozoites. Over a period of almost four years, complete protection from repeated challenge with infective sporozoites was demonstrated in one monkey; protection in two monkeys was obtained on eight of nine occasions, in one monkey on seven of nine occasions, in one monkey on six or nine occasions, and in one monkey on four of eight occasions. Five of six monkeys were protected against infection during the last six challenges. Inoculation with blood-stage parasites at the end of the trial indicated that all animals were susceptible to infection. These results suggest that protection against sporozoite challenge may be strongly reinforced by subsequent exposure to viable sporozoites.
authors.affiliation: Malaria Branch, Centers for Disease Control, Atlanta, Georgia.
authors.forename: W E
authors.initials: WE
authors.lastname: Collins
authors.forename: J C
authors.initials: JC
authors.lastname: Skinner
authors.forename: P
authors.initials: P
authors.lastname: Millet
authors.forename: J R
authors.initials: JR
authors.lastname: Broderson
authors.forename: V K
authors.initials: VK
authors.lastname: Filipski
authors.forename: C L
authors.initials: CL
authors.lastname: Morris
authors.forename: P P
authors.initials: PP
authors.lastname: Wilkins
authors.forename: G H
authors.initials: GH
authors.lastname: Campbell
authors.forename: P S
authors.initials: PS
authors.lastname: Stanfill
authors.forename: B B
authors.initials: BB
authors.lastname: Richardson
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology; D001029:Aotus trivirgatus; D002738:Chloroquine / Q000627:therapeutic use; D007114:Immunization; D016780:Malaria, Vivax / Q000188:drug therapy / Q000276:immunology / Q000517:prevention & control*; D010966:Plasmodium vivax / Q000276:immunology*; D011319:Primaquine / Q000627:therapeutic use; D012453:Saimiri; D013156:Splenectomy
chemical_list: D002738:Chloroquine; D011319:Primaquine