TABLE 1.

ELISA and HI titers for vaccinated pigs

Vaccination and animal	Reciprocal titera
	4 wk postprime		2 wk postboost		Post- challenge HI
	ELISA	HI	ELISA	HI
DNA
Epidermal NP
1	<100	<10	1,600	<10	20
2	<100	<10	800	<10	80
3	<100	<10	1,600	<10	80
Epidermal HA
1	<100	<10	1,600	10	160
2	<100	<10	800	20	5,120
3	<100	<10	800	160	5,120
4	<100	<10	200	40	1,280
Tongue HA
1	<100	<10	3,200	80	2,560
2	<100	<10	3,200	40	5,120
3	<100	<10	1,600	20	5,120
4	<100	<10	12,800	80	5,120
Inactivated whole virus
1	6,400	160	32,000	5,120	ND
2	1,600	40	4,000	80	ND
3	6,400	80	8,000	160	ND
4	800	40	32,000	80	ND
Natural infectionb
1	3,200	160	1,600	NA	80
2	800	40	1,600	NA	40
3	1,600	160	1,600	NA	160
4	800	20	6,400	NA	40
Negative control
1	<100	<10	<10	<10	40
2	<100	<10	<10	<10	80
3	<100	<10	<10	<10	80
4	<100	<10	<10	<10	80

^aND, not determined; NA, not applicable. 

^bThe natural-infection cohort was bled 3 weeks after the first infection and 2 weeks after the second infection.