Human Tissue Preserved since World War I Yields New Clues about 1918 Pandemic

On 27 June 1918, two young German soldiers—one age 18, the other 17—died in Berlin from a new influenza strain that had emerged earlier that year. Their lungs ended up in the collection of the Berlin Museum of Medical History, where they rested, fixed in formalin, for 100 years. Now, researchers have managed to sequence large parts of the virus that infected the two men, giving a glimpse into the early days of the most devastating pandemic of the 20th century. The partial genomes hold some tantalizing clues that the infamous flu strain may have adapted to humans between the pandemic’s first and second waves.

The researchers also managed to sequence an entire genome of the pathogen from a young woman who died in Munich at an unknown time in 1918. It is only the third full genome of the virus that caused that pandemic and the first from outside North America, the authors write in a preprint posted on bioRxiv.  

“It’s absolutely fantastic work,” says Hendrik Poinar, who runs an ancient DNA lab at McMaster University. “The researchers have made reviving RNA viruses from archival material an achievable goal. Not long ago this was, like much ancient DNA work, a fantasy.”

Sequencing viral genomes has become routine. In the ongoing coronavirus pandemic, researchers have amassed a database of more than 1 million genomes of SARS-CoV-2, allowing them to watch variants appear and spread while old ones disappear. But few sequences exist of the H1N1 influenza virus that caused the pandemic of 1918–19. In the early 2000s, scientists in the United States painstakingly pieced together one genome from samples taken from a woman’s body buried and preserved in the frozen ground in Alaska. And in 2013 they presented a second genome from a U.S. flu fatality, teased out from autopsy tissue that had been preserved in formalin at the Armed Forces Institute of Pathology. Both studies were time consuming, costly efforts that few people tried to emulate, says virologist Angela Rasmussen of the Vaccine and Infectious Disease Research Organization at the University of Saskatchewan. Tracking down archived tissue samples is itself a challenge, says evolutionary biologist Michael Worobey of the University of Arizona, a co-author on the new preprint. “It’s all about finding samples,” Worobey says. “Our group has scoured a lot of different locations, and they’re hard to come by.”