Table 5.

The optimal conditions for the detection of serum immunoglobulin G antibodies by different polypeptides in the establishment of indirect ELISA.

Group	Polypeptide coating concentration	Serum dilution ratio	IgG secondary antibody dilution ratio	P/N value
P39	10 μg/mL	1:500	1:40000	5.58
P62	0.25 μg/mL	1:100	1:20000	8.11
P39+P62	10 μg/mL	1:50	1:10000	21.71

positive (P)/ negative (N) [P/N] value = (positive well OD value − blank well OD value)/ (negative well OD value − blank well OD value); When P/N value ≥ 2.1, diagnosis is meaningful. When the P/N value was maximum, the corresponding coating concentration, serum concentration and secondary antibody concentration were the optimal conditions.

IgG = immunoglobulin G.