. 2012 Sep 20;7(9):e45253. doi: 10.1371/journal.pone.0045253

Table 1. Prevalence and levels of antibodies to PfRh4 antigens.

	All	Age²			Enrolment P. falciparum parasitemic status³
		≤9.0 yrs	>9.0 yrs	P⁴	PCR−	PCR+	P⁴
	n = 206	n = 91	n = 115		n = 67	n = 139
PfRh4.2
IgG
Seropositive¹	195	82	113	0.01	60	135	0.042
%	94.7	90.1	98.2		90	97
Median OD	0.24	0.16	0.26	0.01	0.12	0.28	0.0001
[IQR]	[0.08–0.64]	[0.1–0.54]	[0.12–0.7]		[0.04–0.38]	[0.12–0.71]
PfRh4.9	n = 203
IgG
Seropositive¹	195	82	113	0.001	58	137	<0.0001
%	96.1	91.1	100		87.7	100
Median OD	1.23	1.15	1.25	0.6	0.81	1.35	<0.0001
[IQR]	[0.74–1.51]	[0.54–1.58]	[0.87–1.44]		[0.32–1.25]	[0.95–1.55]
PfRh4.4
IgG
Seropositive¹	31	13	18	0.785	8	23	0.386
%	15.1	14.3	15.7		12.0	16.6	0.386
Median OD	0.12	0.12	0.12	0.571	0.12	0.12	0.995
[IQR]	[0.08–0.19]	[0.08–0.19]	[0.08–0.2]		[0.07–0.2]	[0.08–0.19]	0.995
PfRh4.1
IgG
Seropositive¹	78	34	44	0.895	24	54	0.675
%	37.9	37.4	38.3		35.8	38.9
Median OD	0.15	0.15	0.15	0.544	0.15	0.15	0.732
[IQR]	[0.1–0.22]	[0.08–0.21]	[0.1–0.22]		[0.09–0.23]	[0.1–0.22]
PfRh4.2
subclasses
IgG1
Seropositive¹	30	10	20	0.2	5	25	0.045
%	14.6%	11.0%	17.4%		7.5%	18.0%
Median OD	0.06	0.04	0.06	0.36	0.04	0.06	0.056
[IQR]	[0.01–0.12]	[0.01–0.11]	[0.01–0.13]		[0–0.09]	[0.02–0.13]
IgG2
Seropositive¹	17	10	7	0.2	3	14	0.172
%	8.3%	11%	6.1%		4.5%	10.1%
Median OD	0.01	0	0.01	0.32	0	0	0.169
[IQR]	[0–0.01]	[0–0.01]	[0–0.02]		[0–0.11]	[0–0.02]
IgG3
Seropositive¹	182	77	105	0.06	50	132	0.003
%	93.3%	89.5%	96.3%		84.8%	97.1%
Median OD	0.19	0.13	0.25	0.01	0.1	0.25	<0.0001
[IQR]	[0.06–0.63]	[0.04–0.44]	[0.07–0.74]		[0.02–0.25]	[0.07–0.84]	<0.0001
IgG4
Seropositive¹	5	2	3	1.0	2	3	0.661
%	2.4%	2.2%	2.6%		3.0%	2.16%
Median OD	0	0	0	0.15	0	0	0.138
[IQR]	[0–0.01]	[0–0.02]	[0–0.01]		[0–0.01]	[0–0.02]
PfRh4.9 subclasses
IgG1
Seropositive¹	153	63	90	0.14	36	117	<0.0001
%	74.3%	69.2%	78.3%		53.7%	84.2%
Median OD	0.41	0.39	0.44	0.25	0.21	0.54	<0.0001
[IQR]	[0.14–0.78]	[0.10–0.86]	[0.20–0.73]		[0.04–0.48]	[0.23–0.84]
IgG2
Seropositive¹	0	0	0	–	0	0	–
%	0%	0%	0%		0%	0%
Median OD	0	0	0	0.22	0	0	0.111
[IQR]	[0–0.02]	[0–0.02]	[0–0.02]		[0–0.01]	[0–0.02]
IgG3
Seropositive¹	75	17	58	<0.0001	12	63	<0.0001
%	36.4%	18.7%	50.4%		17.9%	45.3%
Median OD	0.07	0.03	0.13	<0.0001	0.03	0.11	<0.0001
[IQR]	[0.02–0.2]	[0.01–0.86]	[0.05–0.27]		[0.01–0.07]	[0.03–0.24]
IgG4
Seropositive¹	15	5	10	0.38	4	11	0.778
%	7.3%	5.5%	8.7%		6.0%	7.9%
Median OD	0	0	0	0.3	0	0	0.130
[IQR]	[0–0.02]	[0–0.02]	[0–0.03]		[0–0.01]	[0–0.03]

Notes:

Seropositive (number of seropositive individuals) and percentage (%) of seropositive individuals were defined by IgG reactivity that was higher than the mean plus three standard deviations of control sera (unexposed donors) measured by ELISA. Median optical densities (OD) are displayed; [IQR] - interquartile range.

Age: ≤9.0 yrs indicates individuals younger than 9 years of age; >9.0 yrs indicates individuals older than 9 years of age.

Parasitemic status: PCR-, indicates P. falciparum was not detected by PCR; PCR+, indicates P. falciparum was detected by PCR.

⁴

P values were calculated using the chi-squared test or Fisher’s exact test for comparisons of seroprevalence, or using the Kruskal-Wallis test for comparisons of antibody level.