Fig. 1: Large NA substrates are needed to detect steric NA inhibitory (NAI) antibodies. | npj Vaccines

Fig. 1: Large NA substrates are needed to detect steric NA inhibitory (NAI) antibodies.

From: Influenza neuraminidase active site proximity assay for rapid profiling of inhibitory antibodies and antigenic drift

Fig. 1

a, b Diagrams showing the detection of NA enzymatic activity with the (a) small monovalent reporter substrate MUNANA and (b) multivalent glycoproteins by ELLA. MUNANA cleavage is monitored by fluorescent detection of the released umbelliferone. Cleavage of the sialylated glycans on the glycoprotein is measured by HRP-conjugated peanut agglutinin (PNA-HRP) binding to the exposed terminal galactose residue. c, d NA activity inhibition by ferret and mouse antisera was measured with a H1N1/CA09 virus by (c) ELLA using the glycoprotein fetuin and (d) MUNANA. Ferret and mouse antisera were generated by intranasal infection with a reassortant virus (H6N1/CA09) carrying a mismatched HA (H6) and a matching NA (N1/CA09). e NA activity in the H1N1/CA09 virus was measured by ELLA in the presence of serially diluted H1 MAbs that inhibit the receptor binding function of the virus (Supplementary Table 1). Purified H1 MAbs were diluted as indicated from an initial concentration of ~1 mg/ml. f NA activity in the H6N1/CA09 virus was measured by ELLA in the presence of serially diluted ferret and mouse antisera raised against the H6N1/CA09 virus.

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