TABLE 3.

IgA antibody responses to homologous, cross-reacting, and heterologous CFs in CS5- and CS7-infected patients

CF of infecting ETEC strain	CF tested for HoM, CR, and HeT antigens	Parameter	Response to homologous CF				Response to cross-reacting CF CS7				Response to heterologous CF CFA/I
			Day 2	Day 7	Day 14	Day 30	Day 2	Day 7	Day 14	Day 30	Day 2	Day 7	Day 14	Day 30
CS5	CS5 (HoM); CS7 (CR); CFA/I (HeT)	GM	199	723	879	412	166	1,138	724	313	122	122	122	127
		Range	142-279	375-1,393	512-1,510	290-586	115-239	535-2,421	471-1,114	203-482	71-208	71-208	87-173	99-162
		P valuea (control)	0.05	0.001	0.001	0.05	NS	0.006	0.001	0.030	NS	NS	NS	NS
		P valueb (days)		NS	0.036	NS		0.045	0.05	NS		NS	NS	NS
							CS5				CFA/I
CS7	CS7 (HoM); CS5 (CR); CFA/I (HeT)	GM	423	2,716	1,596	294	214	453	456	168	71	115	123	95
		Range	272-656	1,309-5,636	1,086-2,344	152-569	137-333	256-802	238-837	79-356	27-122	70-129	85-147	58-139
		P value (control)	0.021	0.003	<0.001	NS	NS	0.01	0.01	NS	NS	NS	NS	NS
		P value (days)		0.035	0.035	NS		NS	NS	NS		NS	NS	NS

^aAntibody titers at acute (day 2) and at convalescence (day 7, day 14, and day 30) stages after onset of diarrhea in patients were compared with the levels in healthy controls.

^bTiters at different time periods at convalescence (day 7, day 14, and day 30) were compared with the titer at the acute phase (day 2) of diarrhea in the patients.