The hepatitis A virus is found worldwide, and has previously been considered to be a purely human pathogen which at most is found in isolated cases in non-human primates. A large-scale study looking into the evolutionary origins of hepatitis A virus suggests that the virus is of likely animal origin like HIV and Ebola.
One of the researchers Jan Felix Drexler from University of Bonn Medical Center in Germany said, "In tropical regions, nearly all young children are infected with the hepatitis A virus and from that time on, they are immune to this disease. By contrast, if adults become infected with the hepatitis A virus, the symptoms can be more serious, and the disease can even have a fatal outcome."
‘When researchers investigated specimens from 209 different species of small mammals from rodents to shrews and bats to hedgehogs, they found that viruses from these mammals were similar to the human hepatitis A virus with regard to their genetic properties, protein structures, immune response and patterns of infection.’
Virologists from University of Bonn Hospital, and their colleagues from several German and international research institutes worldwide, searched for viruses related to the hepatitis A virus. They investigated 15,987 specimens from 209 different species of small mammals from rodents to shrews and bats to hedgehogs.
Viruses from these mammals were found to be very similar to the human hepatitis A virus with regard to their genetic properties, protein structures, immune response and patterns of infection. Drexler said, "The seemingly purely human virus is thus most likely of animal origin. The study enables new perspectives for risk assessments of emerging viruses by investigating functional, ecologic and pathogenic patterns."
The researchers' evolutionary investigations may even hint at distant ancestry of the hepatitis A virus in primordial insect viruses. Drexler said, "It is possible that insect viruses infected insect-eating small mammals millions of years ago and that these viruses then developed into the precursors of the hepatitis A virus."
The findings appeared in the Proceedings of the National Academy of Sciences (PNAS).