What evidence did scientists use to find and identify the influenza virus from 1918?

Scientists identified the 1918 influenza virus by analyzing preserved tissue samples from victims of the pandemic, particularly lung tissues. They employed advanced techniques such as reverse transcription polymerase chain reaction (RT-PCR) and sequencing to extract and analyze viral RNA from these samples. Additionally, they used serological studies to confirm the presence of the virus and its unique genetic characteristics, differentiating it from other strains. This research provided crucial insights into the virus's structure and pathogenicity.