Geneticists have found the “key” to the evolution of the Spanish flu virus
Scientists at the Robert Koch Institute have sequenced large portions of the Spanish flu virus genome. It caused one of the deadliest pandemics in human history in the early 20th century.
Experts isolated the virus from the lungs of two young soldiers who died of illness in Berlin on June 27, 1918. Tissue samples have been stored in the Berlin Museum of the History of Medicine for a hundred years. The study helped to learn more about the early days of the devastating pandemic and understand how the virus changed between the first and second waves, Science reports.
The scientists also succeeded in sequencing the complete viral genome. It was obtained from the body of a woman who died in Munich in 1918. This is the third complete genome of the Spanish flu virus and the first to be obtained outside of North America.
The authors of the scientific work analyzed 13 samples of lung tissue dating from 1900-1913. In three of them, they found fragments of the RNA of the influenza virus, all 1918.
Two samples were from the first, milder wave of the pandemic. Scientists concluded that the virus originated in birds and learned to better adapt to humans between the first and second wave. They found the “key” to the evolution of the virus in the gene for the nucleoprotein, a structural protein that helps determine which species are capable of infecting this pathogen.
The virus samples obtained from German soldiers looked more like bird flu. But viruses that spread during the second wave acquired two mutations in this gene. These mutations helped the virus bypass the body's innate antiviral defense system.
“The virus has evolved to better avoid the human immune response in the early months of the pandemic,” the authors concluded.
Scientists stressed that such research helps to better cope with modern epidemics and pandemics, such as the coronavirus. Previous research showed that the Spanish flu pandemic began with geese and swans. The first cases arose two years before the onset of mass infections, but then this disease was considered safe.
