The antibody response to Plasmodium falciparum Merozoite Surface Protein 4: comparative assessment of specificity and growth inhibitory antibody activity to infection-acquired and immunization-induced epitopes

Table 3 In vitro Growth-Inhibitory Activities of MSP4-Specific Antibodies

Antibody Reagent	Immunogen¹	Specificity²	MSP4 Titre³	% GIA⁴
Polyclonal Sera
S193	rMSP4^GST	Full MSP4	30,000	12
S1619	rMSP4	Full MSP4	100,000	47*
S1620	rMSP4	Full MSP4	30,000	15*
S1621	rMSP4^Sc	Full MSP4	1,000,000	41**
S1622	rMSP4^Sc	Full MSP4	1,000,000	64**
S104	rMSP4A	MSP4A	ND	14
S127/162	rMSP4C	MSP4C	ND	-26
S133	rMSP4D	MSP4D	ND	-18
Mabs
H12	rMSP4	MSP4A		6
1B7	rMSP4	MSP4B		13
6G10	rMSP4	MSP4C		12
4C10	rMSP4	MSP4D		10
1G10	rMSP4	MSP4D		8
7F4	rMSP4	MSP4D		8
8G3	rMSP4	MSP4D		7
1H2	rMSP4	MSP4D		5
6G11	rMSP4	MSP4D		9
6G10+1B7+4C10	rMSP4	MSP4B/C/D		11
PBS control	-	-		5
Control Reagents
Anti-MSP1₁₉ sera				51**
Anti-AMA-1 purified IgG				88**
Anti-GST sera				10

1) Polyclonal and monoclonal antibodies were raised against recombinant MSP4 produced in E.coli as a hexahistidine (rMSP4) or GST (rMSP4^GST, rMSP4A/C/D) tagged protein. S1621 and S1622 were raised against S. cerevisiae-expressed protein (rMSP4^Sc). 2) Specificity confirmed by ELISA and/or immunoblotting. 3) Titre for selected polyclonal sera determined by ELISA against rMSP4. 4) Parasite growth inhibition assay (GIA) results (%). Statistical significance of inhibition by two-tailed student t-test comparing final parasitaemias in wells with test antibody to control culture; p < 0.1 (*), p < 0.01 (**) and p > 0.1. ND: not determined.

ISSN: 1475-2875