Table 1.

Interferon-gamma ELISpot responses to control and listerial antigens. Peripheral blood mononuclear cells isolated on days 0, 35, and 42/49 were cultured with 5 µg/mL antigen. Volunteers 4, 6, and 8 received a control immunization (saline). Counts represent mean values of IFN-secreting spots per million cells in 2 wells using CTL Immunospot ELISPOT Reader with Immunospot 5 counting software. Antigens from left to right: Saline (negative control); PHA (phytohaemagglutinin, positive control) and CEF (cytomegalovirus, Epstein–Barr virus, influenza virus peptides, positive control); LLO (listeriolysin-O peptides); SonWT (sonicated wild-type L. monocytogenes); Sec Lm (secreted listeria antigen).

Assignment	Volunteer	Saline	CEF	LLO	Son Lm	Sec Lm
Placebo	#4 day 0	5	200	3	8	3
	day 42	13	215	5	295*	470*
	#6 day 0	0	0	0	83	33
	day 42	10	33	58	43	60
	#8 day 0	5	15	3	58	390
	day 42	10	20	5	68	198
Active	#1 day 0	20	140	10	283	148
	day 42	3	108	8	473	128
	#2 day 0	13	530	35	175	83
	day 42	15	933	35	200	218*
	#3 day 0	13	90	10	100	18
	day 42	8	30	13	955*	828*
	#5 day 0	8	1285	5	128	110
	day 42	3	1013	50	433*	260*
	#7 day 0	8	628	5	13	38
	*day 49	13	645	5	778*	1548*

The asterisks denote a significant increase as defined in methods.