Fig.5. Validation of the S-iELISA by IFA.
(A) Identification of
SADS-CoV-negative and positive sera by IFA. IPI-FX cells were seeded on
24-well plates and cultured overnight, followed by infection with
SADS-CoV at a MOI of 0.01. Mock-inoculated IPI-FX cell culture showing
normal cells. SADS-CoV-inoculated IPI-FX cells at 1 d.p.i. showing
syncytium (indicated by arrows). At 24 hour postinoculation, cells were
fixed and probed with 111 pig serum samples containing
SADS-CoV-negative, weakly positive, strongly positive serum samples and
1 × PBS, SADS-CoV Ab (-) serum, SADS-CoV Ab (+) serum as controls,
followed by incubation with Cy3-conjugated rabbit anti-pig antibodies
(red). Cell nuclei were counterstained with DAPI (blue). Cells were
observed with a fluorescence microscope. The scale bar represents 100
μm. (B) The specificity and sensitivity of the S-iELISA were analyzed
based on the results of IFA.
Fig.6. Determination of the correlation between SADS-CoV virusneutralization titers and
OD450nm values of S-iELISA.
Seven serum samples were tested by S-iELISA and virus neutralization
assays, respectively. The OD450nm values and
neutralizing antibody titers were compared to determine the relationship
between S-iELISA and the neutralizing antibody of SADS-CoV.