As a virus’ natural host, or target, evolves over time, so do the footprints, or the configuration, of the its molecular key—the RBS.
The change ensures the virus’ compatibility with the host and, in the end, the virus’ survival.
Even though viruses from other viral families can at times cause hemorrhagic fevers, members of the arenavirus family are considered true hemorrhagic fever viruses.
The infections they cause are marked by blood vessel damage and severe bleeding in multiple organs.
Between 15 and 30 percent of people infected with one these viruses develop severe symptoms and die.
Prior to the development of the Junin vaccine in the 1980s, the virus had caused about 30,000 symptomatic infections in Argentina.
In the new study, however, researchers identified a tiny portion in the molecular keys used by Junin and Machupo that is identical and responds to the same antibodies, rendering both viruses sensitive to the same vaccine.
For their experiments, the team started out by obtaining antibodies from a person who had received the Junin vaccine two years prior.
By comparison, outbreaks caused by Machupo have been relatively small and contained—fewer than 100 people sick at a time.
Then again, Abraham points out, up until the 2014-2016 outbreaks in West Africa, Ebola too had caused sporadic, smaller outbreaks affecting dozens to hundreds of people.