The impact of early life exposure to Plasmodium falciparum on the development of naturally acquired immunity to malaria in young Malawian children

Table 2 Magnitude and prevalence of antibodies and IgG responses in parasitaemic and aparasitaemic children at 18 months

Antigen tested/parasite isolate	Median antibody level^a (IQR^b) Number of seropositive^c children (%)			p value^d
Antigen tested/parasite isolate	All children; (n = 601)	Parasitaemic children; (n = 60)	Aparasitaemic children; (n = 541)	p value^d
MSP1 19kD^e	2.80 (0.65, 7.09)	12.31 (4.38, 28.79)	2.37 (0.56, 6.08)	< 0.0001
MSP1 19kD^e	327 (54.4)	53 (88.3)	274 (50.7)	< 0.0001
MSP2^f	2.91 (0.87, 9.04)	15.14 (3.47, 35.16)	2.62 (0.79, 7.28)	< 0.0001
MSP2^f	162 (26.9)	36 (60.0)	126 (23.3)	< 0.0001
EBA175^g	3.38 (1.95, 16.09)	5.89 (2.89, 21.37)	3.24 (1.92, 15.89)	0.0228
EBA175^g	69 (11.5)	15 (25.0)	54 (9.9)	0.001
Rh2A9^h	7.17 (2.1, 25.3)	8.59 (3.28, 19.24)	7.11 (4.05, 13.27)	0.5630
Rh2A9^h	151 (25.1)	23 (38.3)	128 (23.7)	0.013
Schizont	3.30 (1.27, 8.09)	17.31 (5.22, 48.66)	2.95 (1.09, 6.98)	< 0.0001
Schizont	325 (54.1)	58 (96.7)	267 (49.4)	< 0.0001
E8Bⁱ	0 (0, 0.20)	0.15 (0, 0.86)	0 (0, 0.16)	< 0.0001
E8Bⁱ	43 (7.2)	9 (15.0)	34 (6.3)	0.013
R29ⁱ	0 (0, 0.07)	0 (0, 1.12)	0 (0, 0.002)	< 0.0001
R29ⁱ	21 (3.5)	9 (15.0)	12 (2.2)	< 0.0001
3D7ⁱ	0 (0, 0.35)	0.30 (0, 2.08)	0 (0, 0.29)	< 0.0001
3D7ⁱ	50 (8.3)	17 (28.3)	33 (6.1)	< 0.0001

Significant p value in italic format
^aAntibody levels expressed as units relative to positive control
^bInterquartile range
^cSamples defined as antibody positive if levels greater than mean + 3SD of negative controls
^dp value between parasitaemic and aparasitaemic children calculated by Mann–Whitney test or Chi squared test for antibody level or seropositivity, respectively
^eMerozoite surface protein 1
^fMerozoite surface protein 2
^gErythrocyte binding antigen 175
^hReticulocyte binding protein homologue 2A
ⁱVariant surface antigen antibody responses

ISSN: 1475-2875