National Institute of Virology-Microbial Containment Complex, 131/1 Sus Road, Pashan, Pune-411201, India.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
The emergence of avian influenza A (H5N1) virus in humans prompted a series of seroepidemiodological studies to determine mode of transmission of the virus and the risk factors associated with infectioin (Rowe T. et al., 1999). Hemagglutinin inhibition test (HAI), the virus neutralization test (NT) and ELISa are fundamental tools in diagnostic, epidemiologic and immunologic studies. Mainly Horse HAI (HHAI), microneutralization (MN) assays are being used for detection of neutralizing (NT) antibodies (Abs) against influenza A (H5N1) viruses. The receptor specificity of influenza virus HA correlates with the ability to agglutinate erythocytes (red blood cells RBCs) from different animal species. Most avian influenza viruses preferentially bind to sialic acid receptors that contain N-acetylneuraminic acid a2-3-galactose (a2,3-Gal) linkages, while human influenza viruses proeferentially bind to those containing N-acetylneutramine acid a2, 6-galactose (a2, 6-Gel) linkages. The HAI assay using turkey RBCs that express a mixture of a2,3-Gal and a2, 6-Gal linakages is insensitive for the detection of antibody responses to AI viruses. The horse RBCs has been shown to be more sensitive and relatively specific for detecting antibody responses to current H5N1 viruses in human sera. We developed HA and HAI assays using horse and fowl RBCs. These assays were used for detection and identification of H5N1 isolates from both Navapur and Manipur H5N1 outbreaks in poultry and also for detection of viruses during avian influenza surveillance. Both horser and fowl RBCs detected H5N1 viruses from both these outbreaks.
