Hepatitis A: Seals Have Closest-Related Virus to HepA

In fairly electrifying news, the nearest known relative of hepatitis A virus has been found in seals. This could provide vital information in understanding the emergence of hepatitis A, and Columbia University scientists published their research on this in the journal mBio.

"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," lead author Dr. Simon Anthony, said in a statement. "Our findings show that these so-called 'hepatoviruses' are not in fact restricted to primates, and suggest that many more may also exist in other wildlife species."

Hepatitis A affects 1.4 million people worldwide each year. It is a highly contagious viral infection that can cause mild to severe illness. The disease is usually transmitted by the fecal-oral route, through person-to-person contact or by consumption of food or water, as the release noted.

"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 said in the release. "It raises the question of whether hepatitis A originated in animals, like many other viruses that are now adapted to humans."

The study group, from the Center for Infection and Immunity at Columbia University's Mailman School of Public Health, were investigating a deadly strain of avian influenza that killed over 150 harbor seals off the coast of New England in 2011. They performed deep sequencing of all viruses present in three of the marine mammals, in order to see what viruses might co-occur with influenza. The researchers discovered phopivirus, which was found in seven more animals following analysis of more animals off the coast of New England.

It remains unclear whether the virus was transmitted to these animals by humans, or vice versa, or if a third host that has not yet been identified is the original source. Nonetheless, since the virus was found in different species of seals, this study suggests that the virus has been present in seals for a fairly long time. Next, researchers plan to investigate other species that have close interactions with seals to see if they can find other sources of hepatitis A-like viruses, the release noted.

"Coyotes regularly scavenge dead seals along the coast, so it would be very interesting to examine coyotes to see if they have any similar viruses," Katie Pugliares, MS, a senior biologist at the New England Aquarium in Boston, who was also involved in the study, said in a statement.

Since many infectious diseases that have emerged in humans have origins in wildlife, scientists in the Center for Infection and Immunity led by Dr. Anthony have recently been working with partners at the EcoHealth Alliance, University of California, Davis and others within the United States Agency for International Development's PREDICT program, in order to identify potential viral threats to human health from animals, according to the release.

"Our goal is to try to understand drivers of infectious disease emergence thereby enhancing pandemic preparedness," said W. Ian Lipkin, with Columbia, in the release. 

The research appears in the July/August issue of mBio, the online open-access journal of the American Society for Microbiology.

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