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Table 1 Principal characteristics of the ELISAs employed in the study

From: Evaluation of six serological ELISA kits available in Italy as screening tests for equine infectious anaemia surveillance

 

ELISA #1

ELISA #2

ELISA #3

ELISA #4

ELISA #5

ELISA #6

Type

Competitive

Indirect

Competitive

Competitive

Indirect

Indirect

Antigen

Recombinant p26

Recombinant gag and env antigens

Purified p26

Recombinant p26

Recombinant antigen- not specified

Recombinant p26

Run time (‘)

160

135

45

90

20

35

Interpretation Criterion/Formula

\( \mathrm{PI}=100-\left({\overline{\mathrm{OD}}}_{\mathrm{S}}/\overline{{\mathrm{OD}}_{\mathrm{K}-}}\ast 100\right) \)

\( \mathrm{S}/\mathrm{P}={\frac{\left(\overline{{\mathrm{OD}}_{\mathrm{S}}}-\overline{{\mathrm{OD}}_{\mathrm{K}-}}\right)}{\left(\overline{{\mathrm{OD}}_{\mathrm{K}+}}-\overline{{\mathrm{OD}}_{\mathrm{K}-}}\right)}}^{\ast}\;100 \)

Compared to ODK+

\( \mathrm{S}/\mathrm{P}={\frac{\left(\overline{{\mathrm{OD}}_{\mathrm{S}}}-\overline{{\mathrm{OD}}_{\mathrm{K}-}}\right)}{\left(\overline{{\mathrm{OD}}_{\mathrm{K}+}}-\overline{{\mathrm{OD}}_{\mathrm{K}-}}\right)}}^{\ast}\;100 \)

Compared to ODK+

Compared to ODK+

 

PI <30: Neg

S/P ≤ 40: Neg

ODS > ODK+: Neg

S/P ≤ 50: Neg

ODS < ODK+: Neg

ODS < ODK+: Neg

Outcome definition

30 ≤ PI ≤ 50: Equivocal

40 < S/P < 50: Equivocal

ODS≤ ODK+: Pos

50 < S/P < 60: Equivocal

ODS ≥ ODK+: Pos

ODS ≥ ODK+: Pos

 

PI >50: Pos

S/P ≥ 50: Pos

 

S/P ≥ 60: Pos

  1. Gag and env: genes of EIAV respectively coding for nucleocapsid and envelope antigens, PI: percentage inhibition, S/P: Corrected Sample /Positive Ratio;
  2. ODS: Optical Density of Sample; ODK-: Optical Density of Negative Control; ODK+: Optical Density of Positive Control; Neg: Negative; Pos: Positive