Immunization with the binding domain of FimH, the adhesin of type 1 fimbriae, does not protect chickens against avian pathogenic Escherichia coli

Figures & data

Table 1. Mortalities and lesion scores in chickens in vaccination experiment 1

					Median lesion scores (lower quartile–upper quartile)^e
Group	Vaccine^a	Challenge^b	Death^c	Total^d	TAS	AAS	Liver	PRD	Lungs	Total
1	HIM	NDV+CH2	1	11	1^A (0–2)	2^A (0–2)	0^A (0–2)	0^A (0–2)	0^A (0–1)	3^A (1–8)
2	CIM	NDV+CH2	1	11	1^A (0–2)	1^A (0.25–2)	0^A (0–0.75)	0.5^A (0–1.5)	0^A (0–1)	3.75^A (0.75–6)
3	–	NDV	0	11	0^B (0–0)	0^B (0–0.25)	0^B (0–0)	0^B (0–0)	0^B (0–0)	0^B (0–0.25)
4	–	–	0	11	0^B (0–0)	0^B (0–0)	0^B (0–0)	0^B (0–0)	0^B (0–0)	0^B (0–0)
^aHIM, intramuscular FimH156; CIM, placebo, intramuscular PBS.
^bNDV infection was performed at day 31 by spray; infection with APEC strain CH2 was performed at day 34 by nebulization in sterile isolators.
^c,dSome chickens died (or were euthaniszed when diseased) before APEC challenge, but showed no clinical signs of APEC infection, so they were not recorded as mortalities. Therefore, the total number of animals is 11 per group, instead of the initial 12 birds per group. Animals that died after APEC challenge were given a total lesion score of 10.
^eTAS, thoracic air sacs; AAS, abdominal air sacs; PRD, pericardium; Total, total lesion score. Values within a column with different uppercase superscript letters are significantly different (P≤0.05). The median values (lower [Q1] – upper [Q3] quartiles) are shown.

Table 2. Mortalities and lesion scores in chickens in vaccination experiment 2

					Median lesion scores (lower quartile–upper quartile)^e
Group	Vaccine^a	Challenge^b	Death^c	Total^d	TAS	Liver	PRD	Lungs	Total
1	HIM	NDV+CH2	2	11	1.5^A (1–2)	0^AB (0–2)	2^AB (1–2)	1^AB (0–2)	4^A (3–8)
2	CIM	NDV+CH2	4	11	1.5^A (1–2)	0^A (0–2)	2^A (1–2)	1^A (0–2)	4^A (3–8)
3	HIN	NDV+CH2	1	11	1^A (1–1)	0^AB (0–0.5)	1^AB (1–1)	0^ABC (0–0)	2^B (1–2.5)
4	CIN	NDV+CH2	0	10	1^A (1–1)	0^AB (0–0)	1^B (1–1)	0^BC (0–1)	2.5^B (2–3)
5	–	NDV	0	10	0^B (0–0)	0^B (0–0)	0^C (0–0)	0^C (0–0)	0^C (0–0)
^aHIM: intramuscular FimH156; CIM, placebo, intramuscular PBS; HIN, intranasal FimH156; CIN, placebo, intranasal PBS. Primary vaccination was performed at day 10 and booster at day 30.
^bNDV infection was performed at day 31 by spray, and infection with APEC strain CH2 was performed at day 35 by nebulization in sterile isolators.
^c,d Some chickens died (or were euthanized when diseased) before APEC challenge, but showed no clinical signs of APEC infection, so they were not recorded as mortalities. Therefore, the total number of animals is 10 or 11 per group, instead of the initial 12 birds per group. Animals that died after APEC challenge were given a total lesion score of 8.
^eTAS, thoracic air sacs; PRD, pericardium; Total, total lesion score. Values within a column with different uppercase superscript letters are significantly different (P≤0.05). The HIM and CIN groups were not compared, nor were the HIN and CIM groups. The median values (lower [Q1] – upper [Q3] quartiles) are shown.

Figure 1. Sodium dodecylsulphate-polyacrylamide gel electrophoresis of the purified FimH156. MW, molecular mass (kDa); TCP, total cell protein (soluble+insoluble fraction); E1 and E2, elution fractions 1 and 2 after Ni-NTA purification. E1 and E2 were mixed to give the final vaccine. Arrow, FimH156 (17 kDa).

Figure 2. Serum IgG response (dilution 1/400) to FimH156 in experiment 1. The bracketed numbers indicate groups, as presented Table 1. Significant differences between treatments at each time point are indicated by different lowercase letters. The arrow indicates the time of APEC infection (24 d.p.v.). OD was measured at 405 nm. HIM, FimH156 vaccinated and challenged group; CIM, placebo vaccinated and challenged group; NDV, control group (only received NDV).

Figure 3. Serum IgG response (dilution 1/100) to FimH156 in experiment 2. 3a: Intramuscularly vaccinated groups compared with controls. 3b: Intranasally vaccinated groups compared with controls. The bracketed numbers indicate groups, as presented in Table 2. Arrow, APEC infection at 25 d.p.v. Significant differences between treatments at each time point are indicated by different lowercase letters. OD was measured at 405 nm. HIM, vaccinated intramuscularly with FimH156 and challenged; CIM, vaccinated intramuscularly with placebo and challenged; HIN, vaccinated intranasally with FimH156 and challenged; CIN, vaccinated intranasally with placebo and challenged; NDV, control group (NDV only).

Figure 4. Anti-FimH156 (4a) IgA and (4b) IgG response in tracheal washes from birds in experiment 2. Different letters indicate significant differences between groups at that time point. HIM, vaccinated intramuscularly with FimH156 and challenged; CIM, vaccinated intramuscularly with placebo and challenged; HIN, vaccinated intranasally with FimH156 and challenged; CIN, vaccinated intranasally with placebo and challenged; NDV, control group (NDV only).

Figure 5. In vitro binding of APEC 1 to mBSA and inhibition by antisera. 5a: Effect of 1/4, 1/16, 1/64 and 1/256 dilutions of serum or αMM. 5b: Sera, elution buffer or aMM were used at a 1/4 dilution. R-s14/16 and R-s14/17, high-titre anti-FimH156 rabbit sera from 14 days after the first booster from two different rabbits. Sample R-ss10 was collected 10 days after the second booster and sample R-p0 was collected prior to vaccination. C610/21 and C602/21, two anti-FimH156 chicken sera from experiment 1 (chickens 610 and 602 at 21 d.p.v.). αMM, 20% methyl-α-d-mannopyranoside. KUL01, an irrelevant antibody (Mast et al., 1998). Buffer, the standard protein A elution buffer (to which 1/5 volume neutralization buffer was added) in which purified IgG antibodies were dissolved. R-ss10-P and KUL01-P, the purified IgG from R-ss10 and KUL01, respectively. Percentage adhesion is calculated relative to the untreated bacterial suspension (bacteria incubated in PBS in the assay).

Mast , J , Goddeeris , BM , Peeters , K , Vandesande , F and Berghman , LR . (1998) . Characterisation of chicken monocytes, macrophages and interdigitating dendritic cells by the monoclonal antibody, KUL01 . Veterinary Immunology and Immunopathology , 61 : 343 – 357 .

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