1.3 Measuring antibodies to SARS-CoV2 spike protein

This time open the ‘ELISA experiment’.

Then run an assay to detect IgG antibodies against SARS-CoV2 spike protein in the following eight samples, using the experimental conditions you noted down earlier in Activity 2:

• 1-Standard
• 2-Neg.Con
• N9921
• C4443
• C5050
• H1151
• F1949
• Z8207

When you have completed the assay, you should have a plate that looks like Figure 3. (If you have arranged the samples in a different order on the plate, then the appearance will be different, but the results should be the same.) The results from the plate reader will be similar to Figure 4. However, note that the titres will depend on the dilution series chosen, and the identification of positive titres, (highlighted here) depend on the exact experimental conditions and the cut-off value selected.

Figure 3 Developed ELISA plate

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Diagram showing a developed ELISA plate. On the left-hand side, going top to bottom, there are the following labels:

• A: 1-Standard
• B: 2-Neg.Con
• C: N9921
• D: C4443
• E: C5050
• F: H1151
• G: F1949
• H: Z8207

Going along the top, from left to right, there are the following labels:

• 1/2
• 1/4
• 1/8
• 1/16
• 1/32
• 1/64
• 1/128
• 1/256
• 1/512
• 1/1024
• 1/2048
• 1/4096

Figure 3 Developed ELISA plate

Maximise

Figure 4 ELISA Plate reader results with positive samples highlighted and titres shown beneath. (Note that the titres will depend on the dilution series chosen, and the identification of positive titres, (highlighted here) depend on the exact experimental conditions and the cut-off value selected.)

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ELISA plate reader results

450nm
Sample	1	2	3	4	5	6	7	8	9	10	11	12
A: 1-Standard	1.305	1.454	1.277	1.422	1.263	1.066	0.607	0.373	0.202	0.152	0.117	0.104
B: 2-Neg.Con	0.106	0.092	0.085	0.084	0.087	0.080	0.081	0.083	0.086	0.087	0.084	0.084
C: N9921	1.331	1.262	1.452	0.713	0.413	0.252	0.157	0.127	0.104	0.094	0.088	0.084
D: C4443	0.141	0.110	0.102	0.095	0.084	0.086	0.083	0.084	0.080	0.083	0.084	0.087
E: C5050	1.415	1.327	1.173	0.638	0.373	0.239	0.158	0.117	0.101	0.096	0.088	0.085
F: H1151	1.328	1.280	0.966	0.519	0.308	0.197	0.136	0.112	0.094	0.085	0.089	0.087
G: F1949	0.112	0.097	0.094	0.090	0.087	0.088	0.087	0.087	0.085	0.080	0.086	0.084
H: Z8207	1.314	1.454	1.334	1.418	4.458	1.427	0.921	0.485	0.272	0.188	0.125	0.103
	2	4	8	16	32	64	128	256	512	1024	2048	4096

Figure 4 ELISA Plate reader results with positive samples highlighted and titres shown beneath. (Note that the titres will depend on the ...