Hepatitis A Virus in Small Mammals

Hepatitis A Virus is an ancient human pathogen recovered previously only from primates. It is the only species of the genus Hepatovirus with a capsid structure intermediate between that of insect viruses and mammalian picornaviruses.

Scientists conducted a targeted search for hepatoviruses in 15,987 specimens collected from 209 small mammal species globally and discovered highly diversified viruses in bats, rodents, hedgehogs, and shrews, which by pairwise sequence distance comprise 13 novel Hepatovirus species[1].

Hepatitis A Virus is enigmatic in its origins. Ancestral state reconstructions of these novel Hepatoviruses suggest a origin in small insectivorous mammals. Viruses from these mammals are very similar to the (Human) Hepatitis A Virus with regard to their genetic properties, protein structures, immune response and patterns of infection. “The seemingly purely human virus is thus most likely of animal origin,” says lead-scientist Jan Felix Drexler.

The scientists’ evolutionary investigations may even hint at distant ancestry of the hepatitis A virus in primordial insect viruses. “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,” says the virologist from the University of Bonn Medical Centre.

[1] Drexler et al: Evolutionary origins of hepatitis A virus in small mammals in PNAS - 2015