When I first taught classes about hepatitis C, I would review the hepatitis alphabet: Hep A, B, C, D, E, F, and G. Eventually it was discovered that hep F wasn’t real. Hep G was reclassified as GB virus C (GBV-C), and is now known as human pegivirus (HPgV), in the Flaviviridae family and a member of the Pegivirus genus. HPgV can infect humans, but we don’t know if it causes a disease. Research has been mixed, and includes reports that some HIV patients coinfected with HPgV can survive longer than those without it. 
Up until recently, only one human hepacivirus (HCV) and one human pegivirus (HPgV) in the family Flaviviridae are known to exist. That is until now...Abbott and University of California San Francisco published research found a new human virus in some hepatitis C patients. The new virus is tentatively named human pegivirus 2 (HPgV-2), which means that now the old hep G virus is now HPgV-1.


Researchers identified eight complete strains of HPgV-2 along with four partial genomes. Infection with HPgV-2 appears to be blood-borne and associated with HCV, it is not yet known whether this new virus can cause disease. In addition to finding out if the virus causes disease, the scientists are hoping to develop screening tests to detect the virus and its antibody. 
This research is published December 11, 2015 in PLOS Pathogens by Michael Berg and colleagues. Although it was disheartening to imagine that we now appear to have yet another virus that may contaminate the world’s blood supply, it is better to know than not know this information. After all, prior to 1989, hep C didn’t have a name; now it is a curable disease. 
I will let you know when there is more information about this. As a person who contracted HCV from a blood transfusion, I am more than mildly interested in this.