Quantification of HA in H7N9 influenza vaccine using heterogeneous antiserum of the same HA sub-type virus / 中华微生物学和免疫学杂志

ABSTRACT

Objective To study the possibility of using heterogeneous antiserum in single radial immunodiffusion (SRID) for quantitative detection of HA in H7N9 influenza vaccine product when H7N9-specific antiserum is not available in order to establish a testing method for the detection of H 7N9 antigen in any urgent situation.Methods Antisera specific for H7N1, H7N2, H7N3 and H7N7 were obtained from NIBSC and used for SRID assay .Amino acid sequences of hemagglutinins were comparatively analyzed be-tween H7N9 virus and other viruses used to prepare heterogeneous antiserum .The titers of antisera against H7N9 and their homogenous antigens were detected by double immunodiffusion method .Based on the results of homology analysis and cross-reaction, a suitable antiserum was selected and its applicability was further validated by the SRID assay using H7N9 antigen.Results Influenza A virus subtype H7N3 that used for preparation of 07/278 antiserum showed the highest HA homology with H7N9 (97.14%).The titer of 07/278 antiserum against H7N9 antigen was 1 ∶8 as detected by double immunodiffusion assay .The H7N9 anti-gen and the 07/278 antiserum could form a clear precipitation line in SRID assay .The detection of H7N9 antigen in the range of 10 to 40μg/ml showed a good linearity in the standard curve .Conclusion The 07/278 antiserum from NIBSC can be used as an alternative reagent for the quantitative detection of hemaggluti -nin in H7N9 influenza virus vaccine .