An unknown virus was discovered in France in a patient with hepatitis

HEALTH – An unknown virus has been identified in a 61-year-old Frenchwoman. This is not the start of a science fiction film, but the discovery of several French researchers from the Pasteur Institute, the Necker-Enfants Malades Hospital AP-HP, the Imagine Institute of Inserm, Paris-Cité University and the National Veterinary School of Alfort (EnvA). A discovery whose results were published in the journal Emerging Infectious DiseasesJanuary 3, 2023.

Provisionally baptized Human Circovirus 1 (HCirV-1), this hitherto never encountered virus belongs to the circovirus family. These are very resistant small DNA viruses that were identified in the 1970s in different animal species. Hosts to whom they can cause respiratory, renal, dermatological and reproductive problems.

But HCirV-1 is a new virus, different from the animal circoviruses already known. Firstly because it is the first pathogenic circovius for humans. But also because “if the passage of animal viruses to humans is regularly reported in the scientific literature, it is rare for a new virus to be identified in Europe in a patient”emphasizes the Institut Pasteur.

liver damage

The 61-year-old patient with this unknown virus was regularly followed after a heart and lung transplant performed 17 years earlier. But it was the occurrence in her, at the end of 2021, of unexplained chronic hepatitis, which led the doctors to carry out, last March, a genomic sequencing on samples of the diseased tissues. This method consists of reading and deciphering the entire DNA of an individual, in order to identify any variations that may explain a disease.

And so it was by analyzing these tissues that the researchers discovered the ” Human Circovirus 1 “. “ The involvement of HCirV-1 in hepatitis has been demonstrated through the analysis of samples from the patient taken in previous years for her follow-up in the context of her transplants. The results showed that the viral genome of HCirV-1 was undetectable in blood samples from 2017 to 2019, then its concentration peaked in September 2021. “, explains Marc Eloit, one of the authors of the study, head of the Pathogen Discovery laboratory at the Institut Pasteur and professor of virology at the National Veterinary School of Alfort (EnvA).

Although the patient had only mild symptoms, the unknown virus created some liver damage. The researchers estimate that 2 to 3% of liver cells were infected. “ Once this virus had used the resources of the liver cell to multiply, it destroyed it “says Marc Eloit.

Before even knowing what this virus was, the patient was treated and cleared of her hepatitis in November 2021. “After antiviral treatment, liver enzymes returned to normal levels in the patient, indicating a cessation of hepatic cytolysis”reassure the scientists.

The creation of a PCR test

If the origin of the virus remains to be identified, “ as well as the source of the infection itself (contact, food, etc.) », as the Institut Pasteur reminds us, this discovery made it possible to develop a specific PCR test for the diagnosis of hepatitis of unknown origin. It can now be performed by any hospital laboratory.

Especially since new cases arise regularly. ” The cases of acute hepatitis reported in children in the United Kingdom and Ireland last April and reported by the WHO are a reminder of this. “, emphasizes the Institute.

” It is also essential to have the ability to identify a new pathogen when an infection is unexplained and to develop a diagnostic test, as potentially any new case of infection with an emerging pathogen in humans may witness the beginning of an epidemic concludes Marc Eloit.

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