WScientists in France have discovered a previously unknown circovirus that caused mild liver inflammation in a patient. Circoviruses are very small DNA viruses that cause disease mainly in animals, especially birds and pigs.
The patient is 61 years old, she had a heart and lung transplant 17 years ago because she was born with a heart defect, a so-called Eisenmenger syndrome. For this reason, she still takes medication that suppresses her immune system, including tacrolimus and glucocorticoids. Because of this therapy, however, it is particularly susceptible to pathogens.
When she was hospitalized for a bowel infection in November 2021, doctors also noticed damage to her liver, which worsened in the months that followed. She had no symptoms other than a slight weight loss. The doctors had expected that the liver inflammation had been caused by hepatitis viruses, but these could not be detected in samples.
The researchers had not expected this pathogen
“The patient had chronic hepatitis with few symptoms,” says virologist Marc Eloit from the Paris Institute Pasteur. He heads a laboratory that specializes in identifying unknown pathogens. His team analyzed the patient’s blood, urine and tissue samples using various sequencing techniques. This ultimately enabled them to identify the pathogen known as “HCirV-1”. Eloit calls the find “completely unexpected”.
In November 2022, the patient had fully recovered from her liver damage, the authors write in a case report recently published in the journal Emerging Infectious Diseases. Here they collect their results together with a research team from the Necker-Enfants Malades Hospital, among others.
Circoviruses were discovered in 1974 and are found in various birds and mammals, where they cause kidney or respiratory problems, among other things. There is a vaccination for pigs.
HCirV-1 is the first circovirus proven to cause harm in humans, the researchers explain.
How the patient could have been infected is unclear. She had received a blood transfusion 17 months earlier and has two pet cats, who in turn hunt birds outdoors. It could also not be ruled out that she was infected through food, for example by eating infected meat.
Again and again no cause can be found for liver inflammation. “We need to know the cause of hepatitis, and in particular whether it is viral or not, in order to be able to offer appropriate treatment and monitor patients effectively,” says Anne Jamet of the Department of Clinical Microbiology at Necker-Enfants Malades Hospital, who also attends was involved in the study. “The identification of this novel virus, which is pathogenic to humans, and the development of a test that can be carried out by any hospital laboratory provide a new tool.” The scientists have developed a special PCR test, and a blood test is also in the works.