Vaccine against the sporozoite stage of malaria

DETAILED DESCRIPTION OF THE INVENTION The P.
vivax CS gene is set forth below (together with the amino acid sequence for which its codes) ##STR1## The DNA fragment chosen for insertion in the yeast host was; ##STR2## This fragment includes the entire tandem repeat sequence plus a region that is substantially parallel to Region I of Dame, et al Science 225:628 (1984), precedes the repeat region, and codes for the amino acid sequence A E P K N P R E N K L K Q P G.
This sequence includes the subsequence K L K Q P which is conserved in all molarial species that have been investigated to data.
The foregoing DNA fragment was obtained from the entire gene by subcloning a 15kb BllII fragment isolated as described by Arnot et al (U.
S.
Pat.
Ser.
No.
754,645, and Science 230:815-818, Nov.
15, 1985) both incorporated by reference.
It was then inserted in the DNA of modified yeast plasmid pAB24 as described in Example 1 below.
For expression of the P.
vivax CS antigen in yeast, a hybrid promoter comprising the strong yeast glyceraldehyde-3-phosphate dehydrogenase and the glucose regulatable alcohol dehydrogenase-2 (ADH-2) promoter was used.
Fusion of this promoter to heterologous genes allows the growth of yeast cultures to high density using glucose as a carbon source.
Depletion of glucose in the media during fermentative growth leads to concomitant induction of expression of the heterologous protein.
Incorporation of the plasmid into high copy number, autonomously replicating yeast plasmids, and transformation of yeast cells generated strains capable of expressing high levels of CS proteins on induction.
The yeast was grown in culture in YEP medium (1% w/v yeast extract, 2% peptone) with 1% glucose as described in Example 1 below.
Two hundred liters of yeast material were thus obtained and stored at -80.
degree.
C.
The thus obtained yeast material contained a complex mixture of different yeast proteins as well as culture medium additives.
Gel electrophoresis of this material on 7.
5% sodium dodecyl sulfate polyacrylamide gel gave an indication of its heterogeneity (see FIG