Table 1.

Pre-challenge serology. Mean microneutralization titers (n=4 ferrets except at week 51 n=2 ferrets) against the homologous strain in plain font and against VN1203 (the challenge virus) in bold italic font.

	Weeks post first immunization
Vaccine regimen1	3		6		8		10		12		16		20		51
VN1203	52.5	52.5	260	260	580	580	100	100	150	150	135	135	180	180	180	180
VN1203 HA D94N	12.5	22.5	35	40	140	230	52.5	60	35	70	12.5	30	27.5	32.5	20	20
VN1203 HA S124D	12.5	25	30	80	90	560	60	240	40	90	10	50	17.5	45	10	15
VN1203 HA K189R	12.5	25	100	130	160	140	80	60	40	70	20	25	27.5	27.5	25	22.5
VN1203 HA D94N:S124D	17.5	30	90	110	280	480	130	90	55	90	10	17.5	35	65	30	60
VN1203 HA D94N:K189R	17.5	35	120	30	300	110	110	60	85	45	35	10	55	30	20	5
VN1203 HA S124D:K189R	20	25	90	72.5	360	320	200	55	160	60	70	32.5	60	27.5	50	20
VN1203 HA D94N:S124D:K189R	17.5	20	90	35	160	120	150	20	120	55	35	17.5	75	45	20	7.5
DKHUN795	22.5	20	70	22.5	340	55	110	10	130	27.5	62.5	17.5	35	15	25	5
A	12.5	22.5	45	7.5	640	27.5	120	10	140	22.5	45	0	65	7.5	60	0
D	15	17.5	85	7.5	680	42.5	160	16.7	240	20	120	12.5	120	7.5	180	5
PBS	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

¹Ferrets were immunized on weeks 0, 3, and 6 (after the bleed weeks 3 and 6).