Enhanced protective immunity of the chimeric vector-based vaccine rAdV-SFV-E2 against classical swine fever in pigs by a Salmonella bacterial ghost adjuvant

Table 1 CSFV-specific neutralizing antibodies in pigs following lethal CSFV challenge

Groups	Days post-immunization (days post-challenge)
Groups	0	21	28 (0)	31 (3)	34 (6)	37 (9)
A: rAdV-SFV-E2 (10⁶ TCID₅₀)	<10	<10	122 ± 52	62 ± 9	699 ± 88	841 ± 258
B: rAdV-SFV-E2 (10⁵ TCID₅₀) + BG (10¹⁰ CFU)	<10	14 ± 2	164 ± 39	147 ± 65	484 ± 66	612 ± 89*
C: rAdV-SFV-E2 (10⁵ TCID₅₀)	<10	<10	<10	<10	<10	194 ± 83
D: BG (10¹⁰ CFU)	<10	<10	<10	<10	<10	<10
E: DMEM	<10	<10	<10	<10	<10	<10

Five groups of pigs (n = 4) were immunized and challenged as described in the “Materials and methods” section. Serum samples were collected at different times following immunization and challenge and subjected to detection of anti-CSFV neutralizing antibody titers by serum–virus neutralization test. The diluted sera were mixed with equal volume of 200 TCID50 CSFV Shimen strain and incubated for 60 min at 37 °C. The serum–virus mixtures were inoculated to confluent PK-15 cells cultured in 96-well plates and incubated for 60 min at 37 °C. The inoculated cells were then incubated for 72 h at 37 °C. IFA was performed as described previously [6]. The cells were examined under a fluorescence microscope, and the titers of CSFV-specific neutralizing antibodies were determined and expressed as the reciprocal of the highest dilution at which infection of the PK-15 cells was inhibited in 50% of the culture wells.
* Significant difference between groups B and C (P < 0.05).
CFU: colony forming units.

ISSN: 1297-9716