Serum strain-specific or cross-reactive neuraminidase inhibiting antibodies against pandemic А/California/07/2009(H1N1) influenza in healthy volunteers

Table 2 Homologous and cross-reactive antibodies against NA of H1N1/2009pdm among participants examined in 2010

Group	HI antibody levels against A/H1N1 influenza viruses		Age, years Me(Q1;Q3)	Antibodies to H1N1/2009pdm				Antibodies to H1N1/1999
	HI antibody levels against A/H1N1 influenza viruses			HI titers, log2		NI titers, log2		HI titers, log2		NI titers, log2
	H1N1/2009pdm	seasonal A/H1N1 viruses		Me (Q1;Q3)	% ≥ 1:40	Me (Q1;Q3)	% ≥ 1:40	Me (Q1;Q3)	% ≥ 1:40	Me (Q1;Q3)	% ≥ 1:40
I	≤1:10	≤ 1:20	45 (6; 58)	2.3 (2.3;2.3)	0	2.3 (2.3;3.2)	2.4	2.3(2.3; 2.3)	0	2.3 (2.3; 4.1)	2.4
N = 41	≤1:10	≤ 1:20	45 (6; 58)	2.3 (2.3;2.3)	0	2.3 (2.3;3.2)	2.4	2.3(2.3; 2.3)	0	2.3 (2.3; 4.1)	2.4
II	≤1:10	≥ 1:40	17 (10; 26)	2.3¹ (2.3; 3.3)	0	3.4² (2.3; 4.3)	15.7	6.2(4.3; 8.3)	72.5	5.3 (4.1; 6.2)	51.0³
N = 51	≤1:10	≥ 1:40	17 (10; 26)	2.3¹ (2.3; 3.3)	0	3.4² (2.3; 4.3)	15.7	6.2(4.3; 8.3)	72.5	5.3 (4.1; 6.2)	51.0³
III	≥ 1:20	any	15 (12; 20)	5.3 (4.3; 6.3)	65.7	5.2⁴ (3.9; 5.6)	38.8	5.3(2.3; 7.3)	56.7	5.5 (3.9; 6.4)	55.2
N = 67	≥ 1:20	any	15 (12; 20)	5.3 (4.3; 6.3)	65.7	5.2⁴ (3.9; 5.6)	38.8	5.3(2.3; 7.3)	56.7	5.5 (3.9; 6.4)	55.2

Key: N (number), Me (medians), Q1; Q3 (lower and upper quartiles); % (percent).
¹Titers of HI antibodies against H1N1/2009pdm are similar in group I and group II (Dunn’s test: z’ = 0.959, p = 1.0).
²Titers of NI antibodies H1N1/2009pdm are higher in group II than in group I (Dunn’s test: z′ = 2.421, p = 0.046).
³In group II, percentage of volunteers with antibody titers ≥ 1:40 to NA of seasonal H1N1/1999 higher than to NA of H1N1/2009pdm (McNemar test: p < 0.001).
⁴Titers of NI antibodies against H1N1/2009pdm are higher in group III than in group II (Dunn’s test: z′ = 4.043, p = 0.0002).

ISSN: 1756-0500