Hepatitis B Virus in White Suckers

The white sucker (Catostomus commersonii) is a freshwater fish that lives in the upper Midwest and Northeast in North America, but is sporadically found as far south as Georgia and New Mexico in the south and west. This bottom feeder is commonly known as a 'sucker' due to its fleshy papillose lips that suck up organic matter from the bottom of rivers and streams.

The white sucker is not primarily fished for food, though some consider it good to eat. When it is eaten by humans, it is usually processed and sold under the name of mullet.

[white sucker (Catostomus commersonii)]

Recently, scientists sequenced the full genome of a hepatitis B-like virus that infects white suckers from the Great Lakes Region of the USA. Research found a novel Hepatitis B Virus, they called White Sucker Hepatitis B Virus (WSHBV)[1].

The level of divergence in protein sequences between WSHBV other hepadnaviruses, and the identification of an Hepatitis B Virus-like sequence in an African cichlid, Ophthalmotilapia ventralis.[2] provide evidence that a novel genus of the family Hepadnaviridae may need to be established that includes these Hepatitis B-like viruses in fishes.

[African cichlid, Ophthalmotilapia ventralis]

While tumors are found in infected white suckers, we do not know if there is an association between an infection with White Sucker Hepatitis B Virus and tumors in the white sucker. Scientists do observe liver tumors in these fish, but not all fish with tumors are virus positive or vice versa.

Suddenly there's an entirely new reservoir of the elusive Hepatitis B Viruses. It may be some time before research may find other fishy hosts. Iwanowicz, one of the researchers, told me that 'these viruses are genetically very different from those that infect humans or birds, and they are not likely a risk to humans. This virus is missing the X-protein that is associated with tumor induction in the HBVs that infect mammals. These viruses are so different that we are in the process of proposing an new genus altogether. They are likely one more snap shot of HBV evolutions'.

Thus, Hepatitis B viruses in birds (avian) and mammals (mammalian) might soon have company from a new family of Hepatitis B viruses in fishes (piscinian).

[1] Hahn et al: Characterization of a Novel Hepadnavirus in the White Sucker (Catostomus commersonii) from the Great Lakes Region of the USA in Journal of Virology - 2015
[2] Personal communication with Luke Iwanowicz: 'We did scour publicly available gene databases and found a sequence for a hepatitis b-like protein in an African cichlid, Ophthalmotilapia ventralis'.