Nanobody-horseradish peroxidase fusion protein as an ultrasensitive probe to detect antibodies against Newcastle disease virus in the immunoassay

Table 3 Optimised dilution of tested chicken sera for cELISA

No. serum	Sera type	1:10	1:20	1:40	1:80	1:160	1:320	1:640	1:1280
1	Positive	0.14	0.16	0.24	0.44	0.73	0.97	0.98	0.93
	Negative	0.90	1.03	1.06	1.06	1.02	1.09	1.02	1.08
	P/N	0.15	0.16	0.23	0.42	0.72	0.89	0.96	0.87
2	Positive	0.10	0.13	0.24	0.50	0.80	1.00	1.12	1.03
	Negative	0.90	1.03	1.00	1.02	0.99	1.01	1.13	1.16
	P/N	0.11	0.13	0.24	0.48	0.81	0.99	0.99	0.89
3	Positive	0.08	0.11	0.16	0.38	0.73	0.94	1.11	1.12
	Negative	1.01	1.09	1.10	1.11	1.09	1.17	1.14	1.20
	P/N	0.08	0.10	0.15	0.35	0.67	0.80	0.97	0.94
4	Positive	0.08	0.10	0.14	0.24	0.55	0.84	0.96	1.02
	Negative	0.89	1.00	0.90	1.00	1.02	0.89	1.08	1.06
	P/N	0.09	0.10	0.16	0.24	0.54	0.95	0.89	0.96

Four positive and negative chicken sera were separately used for cELISA detection. The dilutions of sera were 1:10, 1:20, 1:40, 1:80, 1:160, 1:320, 1:640, and 1:1280. The best dilution was selected when the OD_450nm value of positive to negative (P/N) sera was smallest

ISSN: 1477-3155