All four persons, who had arrived here from abroad in the last few days and were suspected to be suffering from H1N1 flu , have tested negative for the virus.The samples taken from an NRI from Ontario in Canada , who was admitted to a hospital here after he complained of flu like symptoms on May 3, have also tested negative for the H1N1 virus, Professor, Respiratory Medicine at Government Chest Hospital Dr Sudhakar told PTI.