The production and development of H7 Influenza virus pseudotypes for the study of humoral responses against avian viruses

In recent times, high pathogenicity avian influenza (HPAI) H5N1, low pathogenicity (LPAI) H9N2 and both HPAI and LPAI H7 viruses have been disastrous for the economies of affected countries reliant on poultry production and a serious public health concern. These viruses have repeatedly caused zoonotic disease in humans leading to enhanced concern about a potential influenza pandemic with a chance to cross species-specific barriers. Despite the great attention attributed to the HPAI H5N1 avian influenza outbreak in 1997, some H7 strains have also shown to be occasionally adaptable to infecting humans. Therefore, applying knowledge acquired from the study of H5 virus evolution and spread to the development of sensitive serological methods, will improve our ability to understand and respond to the emergence of other HPAI and LPAI viruses that are present within avian populations but have the potential to infect humans and other species. In the present study we describe the construction and production of lentiviral pseudotypes bearing envelope glycoproteins of LPAI and HPAI H7 avian influenza viruses, which were responsible for severe outbreaks during the past decade. The H7 pseudotypes were evaluated in pseudotype-based neutralization (pp-NT) assays in order to detect and quantify the presence of neutralizing antibodies in avian sera, which were confirmed H7 positive by inhibition of haemagglutination (HI) test. Overall results confirmed influenza virus pseudotype neutralization as a robust tool that will improve our understanding of influenza sero-surveillance, thus helping to control the spread of certain subtypes with pandemic potential.