Two nanobody-based immunoassays to differentiate antibodies against genotype 1 and 2 porcine reproductive and respiratory syndrome virus

Table 1 Optimized amounts of PRRSV-1-N protein as the coating antigen and dilutions of g1-2-PRRSV-N-Nb3-HRP and g1-PRRSV-Nb136-HRP fusion protein using the direct ELISA

Nanobody-HRP fusion protein	Amount of PRRSV-1-N protein (ng/well)	Dilutions of nanobody-HRP fusion proteins
Nanobody-HRP fusion protein	Amount of PRRSV-1-N protein (ng/well)	1:10	1:50	1:100	1:200	1:400	1:800
g1-2-PRRSV-N-Nb3-HRP	50	2.008	1.127	0.88	0.463	0.212	0.143
	100	2.199	1.443	1.018	0.597	0.318	0.208
	200	2.339	1.709	1.349	0.8	0.423	0.246
	400	2.387	2.079	1.742	1.26	0.618	0.711
	800	2.384	2.121	1.818	1.402	0.731	0.911
g1-PRRSV-N-Nb136-HRP	50	0.751	0.334	0.243	0.161	0.108	0.091
	100	1.025	0.433	0.305	0.242	0.17	0.128
	200	1.551	0.763	0.509	0.351	0.23	0.173
	400	1.856	1.144	0.799	0.518	0.361	0.254
	800	2.088	1.491	1.101	0.704	0.527	0.408