Each year, millions of people across the globe depend on life-saving blood transfusions. Needless to say, ensuring this limited supply is clean is imperative to ensure the safety of vulnerable recipients. This message has just been highlighted by a new study, which identified a novel human virus that seems to be transmissible by blood products. Furthermore, it appears to be strongly linked with the hepatitis C virus.
Though clearly blood-borne and infectious, at this stage scientists don’t know whether the virus, provisionally called human pegivirus 2 (HPgV-2), can cause disease. But what is interesting is that back in September, a separate, independent study also identified this virus from a different sample of people. Though given a slightly different name, human hepegivirus 1 (HHpV-1), the authors of the present study are confident they are not distinct entities.
“Their virus is about 4 percent different across the genome compared to ours,” one of the study’s lead investigators John Hackett Jr., Ph.D., manager of Abbott's Virus Discovery Program, told IFLScience. “It’s essentially the same virus, so the data is mutually supportive of this being a novel virus. A committee will resolve what the final name is.”
Described in the journal PLOS Pathogens, this is the second pegivirus to have been documented to date, the other being human pegivirus (HPgV). Both of these, alongside hepatitis C virus (HCV), belong to a family of viruses called Flaviviridae.
The investigation started off with an index case, a 70-year-old, HCV-infected woman who had a history of injecting drug use and multiple blood transfusions to treat the blood disorder sickle-cell anemia. She died shortly after being admitted to the University of Chicago Medical Center back in 2011 due to multi-organ failure following sepsis.
Using a technique called next-generation sequencing, which allows for millions of genetic sequences from a sample to be read in parallel, the team was able to establish the presence of this novel virus. The researchers then took this information and used it to come up with tools for the screening of further samples. These were both molecular, looking for viral genetic information, and serologic, searching for antibody responses that would be indicative of infection and not sample contamination.
After searching through an additional 2,400 samples, all of whom were considered high risk for viruses like HIV and HCV due to their circumstances or lifestyles, 11 further cases of this virus were identified. What was interesting was that all of these 12 patients were also infected with HCV; no cases were found in those infected solely with HIV or hepatitis B virus.
“We found this strong association with hepatitis C,” said Hackett. “Whether this indicates something about the route of transmission, or whether the virus persists more when HCV is present, currently we have no idea. But I wouldn’t rule out that we will find it in other settings.”
While Hackett adds that currently they have no data to support that HPgV-2 is pathogenic, or capable of causing disease, studies like this are crucial to keep blood banks as safe as possible.
“HPgV-2 is a blood-borne virus we were unaware of before,” Hackett said. “If you don’t know it’s there, you can’t screen for it.
“We identify novel viruses, that’s part of the effort. It’s then establishing whether there is a link to human disease. By virtue of that answer you decide whether you manufacture an assay to screen blood.”
But VDDC’s work doesn’t end at discovering new viruses: Scientists are also working on developing assays for use in the clinic that could improve disease diagnostics. For instance, if testing windows can be slashed, responses to outbreaks could be improved.