Researchers have discovered a novel virus in seals, and it’s genetically similar to the hepatitis A virus found in humans, according to new work published in mBio this week.
Hepatitis A is a highly contagious liver infection that’s typically transmitted through person-to-person contact or by consuming contaminated food and water. It affects 1.4 million people around the world every year. "Until now, we didn't know that hepatitis A had any close relatives, and we thought that only humans and other primates could be infected by such viruses," Columbia’s Simon Anthony says in a statement. Turns out, these so-called hepatoviruses aren’t restricted to primates – and they may exist in many other wildlife species too.
Researchers stumbled on the new virus back in 2011 when they were investigating a fatal strain of bird flu that killed over 150 harbor seals (Phoca vitulina) off the coast of New England. To figure out what viruses are co-occurring with influenza, the team sequenced all of the viruses present in three of the seals. The new virus, which they named phopivirus, appears to be common, but it doesn’t seem to cause the seals any harm. Although, if it behaves like hepatitis A, phopivirus may only cause disease in adult animals. When the team examined another 29 harbor seals, six harp seals, and two grey seals living nearby, they found the phopivirus in seven more animals – indicating that the virus has been around in seals for a long time.
"Our data suggest that hepatitis A and this new virus share a common ancestor, which means that a spillover event must have occurred at some point in the past," Anthony adds. "It raises the question of whether hepatitis A originated in animals, like many other viruses that are now adapted to humans." It’s also possible that the virus ancestor spilled over to seals from humans, or perhaps a third, as-yet unidentified host is involved.
Next, the team plans to look at animals who interact closely with these seals to see if other wildlife harbor these new hepatitis A-like viruses. Coyotes, for example, regularly scavenge dead seals along the coast. They might also study people who eat seal meat.