Virus replicon particles expressing porcine reproductive and respiratory syndrome virus proteins elicit immune priming but do not confer protection from viremia in pigs

Table 2 Seroconversion after vaccination of pigs with VSVΔG(GP5/M) followed by PRRSV challenge.

Ab against PRRSV Ag (by ELISA)	Vaccine	ELISA	Days after PRRSV challenge infection
Ab against PRRSV Ag (by ELISA)	Vaccine	ELISA	0	2	4	6	8	10	13	21
GP5	VSVΔG(GP5/M)	Positive/total pigs	0/5	0/5	0/5	2/5	2/5	4/5	5/5	5/5
		% Competition^a (positive pigs)	0	0	0	50 ± 12	49 ± 29	82 ± 15	82 ± 20	69 ± 15
		Range for positive pigs	0	0	0	41–59	31–66	64–101	59–106	49–91
	VSV*ΔG (control)	Positive/total pigs	0/5	0/5	0/5	0/5	0/5	0/5	0/5	2/5
		% Competition (positive pigs)	0	0	0	0	0	0	0	62 ± 13
		Range for positive pigs	0	0	0	0	0	0	0	53–72
N	VSVΔG(GP5/M)	Positive/total pigs	0/5	0/5	0/5	0/5	0/5	2/5	4/5	4/5
		S/P ratio^b (positive pigs)	0	0	0	0	0	0.9 ± 0.4	1.0 ± 0.5	1.2 ± 0.1
		Range (positive pigs)	0	0	0	0	0	0.5–1.2	0.6–1.7	1.1–1.3
	VSV*ΔG (control)	Positive/total pigs	0/5	0/5	0/5	0/5	0/5	0(1)/5	4/5	3/5
		S/P ratio (positive pigs)	0	0	0	0	0	0	0.7 ± 0.2	1.4 ± 0.8
		Range (positive pigs)	0	0	0	0	0	0	0.4–0.9	0.4–1.9

IDEXX X3 kit S/P ratios of >0.4 are considered positive. The mean values are indicated with the standard deviation.
^a% Competition = (negative control mean [mean of optical absorbance] − sample mean)/(negative control mean − positive control mean) × 100. The mean values are indicated with the standard deviation.
^bS/P ratio = (sample mean [mean of optical absorbance] − negative control mean)/(positive control mean − negative control mean).

ISSN: 1297-9716