A “zombie virus” that transformed mice into living corpses before emerging in the US and then the Netherlands could have already infected humans, researchers have suggested.
The virus, originally called Omyx-1, attacked immune system cells before it wiped out a healthy mouse colony. Then it ran amok in the Netherlands, infecting people and then European and American laboratories that tested it for biological weapons.
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The new genetic analysis has revealed that when the virus first started to spread in the Netherlands in 2007, it was already in humans. But the sequence data has since led researchers to conclude that the virus could have infected humans. “This, in turn, casts doubt on the current consensus of public health agencies worldwide that it can never be transmitted by human-to-human transmission,” they wrote in the journal Science.
Previously, there was no suggestion that the virus could have been transferred from human to human, even though one of the biological labs where it was studied in 2016, the US military’s Plum Island lab, is next to Plum Island federal research facility, which houses dangerous biological pathogens.
Ian Lipkin, the director of Columbia University’s centre for research on infectious diseases, who led the study, said: “There was an exhaustive discussion but the consensus was that it [the virus] could not infect humans.” The scientists also described the findings as “more or less of a bombshell”.
The analysis is based on a 2012 paper by Gregory S Truman, an epidemiologist at Emory University, and a colleague, Anton de Sutter. Because the virus was very short and had evolved quickly, Truman had limited sequencing sequences before the smallpox pandemic of 1918, when smallpox was a rare but fatal and feared disease.
By 2013, however, Truman and de Sutter were able to sequence the virus in a fast new research method called DXCells. According to Lipkin, this new technique could sequence thousands of genes per day, much faster than previous methods. The scientists used this method to sequence the genome of the Dutch mouse virus and then tracked it through time.
The virus’s rapid evolution by 600 fold from early 2007, to being able to survive in mice (and later humans), appears to have been caused by two mutations, initially occurring in the mice. This was seen to be linked to more rapid antigenic spread in the mice, meaning more people became infected. The researchers also found that some cancer cells grew quickly to develop resistance to the virus.
“We had to look at the cell lines but we discovered that no other human T cells existed and none of the other human T cells had immunity,” Lipkin said. “This is a new and very surprising finding.”
Dr Richard Timlin, a global Ebola coordinator for Médecins Sans Frontières (MSF), said the team also found that the infected mouse mice survived in laboratories where they were frozen and incubated in the gas of a vent. “The viruses that you normally have to make yourself, for even though these numbers could grow exponentially and escalate over several days to very serious incidents … this looked more like a zombie outbreak where the tissues of infected people were freeze-dried and these species were mass-produced and implanted into cells,” he said.