Of particular interest was the finding that IgY raised against H5N1 could neutralize an H1N1 computer virus but that when IgY to H1N1 was tested against H5N1 it did not show cross-inhibition, while it was able to neutralize a heterologous strain of H1N1. vitroassays to test for the ability of IgY to inhibit hemagglutination Alanosine (SDX-102) (HI test) and computer virus infectivity (serum neutralization test), IgYs inhibited the Alanosine (SDX-102) homologous as well as in some cases heterologous clades and strains of viruses. Using anin Alanosine (SDX-102) vivomouse model system, we found that, when administered intranasally 1 h prior to contamination, IgY to H5N1 guarded 100% of the mice against lethal challenge with H5N1. Of particular interest was the finding that IgY to H5N1 cross-protected Alanosine (SDX-102) against A/Puerto Rico/8/34 (H1N1) bothin vitroandin vivo. Based on our results, we conclude that anti-influenza computer virus IgY can be used to help prevent influenza computer virus infection. == INTRODUCTION == Influenza viruses have been the cause of the most devastating infectious disease pandemics in CXXC9 the Alanosine (SDX-102) world. The Spanish flu of 1918 killed over 50 million people, with an overall mortality rate of 2.5% in the United States. Thus far (April 2011 statistics), the current highly pathogenic avian influenza (HPAI) computer virus strain H5N1 has infected 486 people, with a 60% mortality rate. Seasonal influenza outbreaks have also had powerful impacts on human health, with 20,000 to 40,000 people (mainly the elderly) dying each year in the United States alone. Recently, the world has experienced an outbreak of a new pandemic strain, H1N1 09, which originated in Mexico and then spread worldwide very rapidly. Over the first 6 months of the pandemic, 340,000 people became infected, with over 4,000 deaths (1.2% mortality rate of infected people), many of them young children. Until March 2010, nearly 16,000 deaths were attributed to this new strain of H1N1. The means of control for influenza are based on antiviral drugs (neuraminidase and ion channel inhibitors) and killed or attenuated vaccines. However, both drug resistance and vaccine development and production problems pose troubles for influenza control programs. For example, the very stable antiviral drug oseltamivir (Tamiflu) has been found in watercourses in Japan where ducks that harbor influenza A viruses come into direct contact with the drug, potentially leading to the selection of oseltamivir-resistant strains of influenza computer virus (2). In addition, vaccine production can be problematic, due to the difficulty of working with highly pathogenic avian influenza (HPAI) viruses, the relatively low immunogenicity of some strains, and the need to protect against the large number of strains of H5N1, H7N1, H9N3, etc., circulating in the environment. The influenza vaccine production problem has been observed in the current pandemic, where even after 6 months only a limited supply of commercial vaccine was available. Due to these problems, it is crucial to develop a new means of influenza therapy that can quickly provide protection against a wide range of influenza viruses, particularly within the first few months of the start of a pandemic. In the present study, we tested the potential use of chicken IgY as a means of providing passive immunoprophylaxis against influenza viruses. The advantages of using IgY rather than serum or monoclonal antibodies are that it is easy and cheap to produce (5) and often recognizes highly conserved epitopes not normally seen by the mammalian immune system. Furthermore, it can be administered orally (11) and is well tolerated in humans, and one can utilize commercial laying hens that are globally available for each individual country to be able to produce and stockpile. In addition, IgY antibody can be purified, stored for lengthy periods of time even at room heat, and formulated to provide rapid passive protection in hospitals, airplanes, and workplaces. In order to test this hypothesis, laying hens were immunized with purified and inactivated influenza computer virus strains H1N1, H3N2, and H5N1 in Freund’s adjuvant. Enriched IgY preparations were produced from egg yolks collected at the.