Table 2 Calculation of the neutralizing antibody titer determined with NT-PCR assay (1.) and its intra- and inter-assay variability (2.)

1:40

0.0250

0.25

0.31

0.27

0.33

0.22

0.32

0.31

1:80

0.0125

1.34

1.37

1.31

1.37

1.26

1.35

1.42

1:160

0.0063

1.44

1.36

1.28

1.27

1.30

1.23

0.71

1:320

0.0031

1.61

1.52

1.45

1.49

1.17

1.44

1.11

1:640

0.0016

1.20

1.77

1.65

1.73

1.41

1.65

1.43

1:1280

0.0008

1.23

1.34

1.30

1.54

1.30

1.41

1.06

1:2560

0.0004

1.24

1.36

1.39

1.38

1.31

1.46

1.26

1:5120

0.0002

0.25

0.31

0.27

0.33

0.22

0.32

0.31

respective NT-PCR titer for each assay

day 1

day 2

day 3

day 4

inter-assay variability

assay 1

1:320

assay 3

1:640

assay 4

1:640

assay 5

1:640

1:640± one dilution

assay 2

1:640

assay 6

1:640

assay 7

1:640

intra-assay variability

1:640± one dilution