Novel application of Influenza A virus inoculated chorioallantoic membrane to characterize a nucleoprotein specific monoclonal antibody for immunohistochemistry assay.

Monoclonal antibody (MAb) is widely applied in disease diagnosis. Here we report a MAb, 1 WF-4, against Influenza A virus nucleoprotein (NP), its broad response with Influenza A virus , and its application in immunohistochemistry (IHC) assay. WF-4 was screened by immunofluorescence assay (IFA). The results showed that its reactivity with baculovirus expressed full-length recombinant NP (rNP) in western blot (WB) and applicability in IHC. Fifteen Influenza A virus reference subtypes, H1 to H15, infected chicken embryonated chorioallantoic membranes (CAM) fixed by formalin, were all detectable in WF-4 based IHC. Also, the reactivity of the IHC test with NP from experimentally inoculated H6N1 and from all recent outbreak of H5 subtype avian Influenza A virus (AIV) field cases in Taiwan showed positive results. Our data indicate that CAM, the by-product of Influenza A virus preparation, is helpful for Influenza A virus specific MAb characterization, and that MAb WF-4 recognizes conserved and linear epitopes of Influenza A virus NP. Therefore, WF-4 is capable of detecting NP antigen in IHC and may be suitable for developing various tests for diagnosis of Influenza A virus , and especially AIV infection.