Continuing evolution of highly pathogenic (HP) H5N1 influenza viruses in wild birds with transmissions to domestic poultry and humans poses a pandemic threat. There is an urgent need for a simple and rapid serological diagnostic assay which can differentiate between antibodies to seasonal and H5N1 strains that could provide surveillance tools not dependent on virus isolation and nucleic acid technologies. Here we describe the establishment of H5N1 SeroDetect ELISA and rapid test assays based on three peptides in HA2 (488-516), PB1-F2 (2-75), and M2e (2-24) that are highly conserved within H5N1 strains. These peptides were identified by antibody repertoire analyses of H5N1 survivors in Vietnam using whole genome phage display libraries (GFPDL). To date, both platforms demonstrated high levels of sensitivity and specificity in detecting H5N1 infections (clade 1 and clade 2.3.4) in Vietnamese patients as early as 7 days and up to several years post infection. H5N1 uninfected individuals in Vietnam and the US, including subjects vaccinated with seasonal influenza vaccines or confirmed seasonal infections, did not react in the H5N1-SeroDetect assays. Moreover, sera from individuals vaccinated with H5N1 subunit vaccine with moderate anti-H5N1 neutralizing antibody titers did not react positive in the H5N1-SeroDetect ELISA or rapid test assays.
The simple H5N1-SeroDetect ELISA and rapid tests could provide an important tool for large scale surveillance for potential exposure to HP H5N1 strains in both humans and birds.
1 Division of Viral Products, Center for Biologics Evaluation and Research (CBER), FDA
2 National Institute of Health Research and Development, Jakarta, Indonesia
3 Wellcome Trust Major Overeas Program - Oxford University Clinical Research Unit, Hanoi, Vietnam
4 National Hospital of Tropical Diseases, Hanoi, Vietnam
5 National Institute of Hygiene and Epidemiology, Vietnam
6 National Hospital of Pediatrics' Hanoi, Vietnam
* Corresponding Author: Division of Viral Products, Center for Biologics Evaluation and Research (CBER),FDA, Bldg-29B, Rm-4NN02 8800 Rockville Pike Bethesda, MD, USA 20892. Phone- 301-827-0739 Fax- 301-496-1810 E. mail- email@example.com