An unknown species of circovirus has been identified. Explanations from Marc Eloit, head of the Pathogen Discovery laboratory at the Institut Pasteur.
Par Johanna Amselem
© ERIC AUDRAS / AltoPress / PhotoAlto via AFP
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CThis is not the start of a fiction, but a real discovery. Scientists from the Institut Pasteurthe Necker-Enfants Malades Hospital AP-HP, Inserm within the Imagine Institute, Paris Cité University and the National Veterinary School of Alfort (EnvA) have identified a still unknown species of circovirus linked to hepatitis in humans.
Her name ? Human Circovirus 1 (HCirV-1). Where is he from ? It belongs to the circovirus family. These very resistant small DNA viruses were identified in 1974 in different animal species. These can be responsible for respiratory, renal, dermatological and reproductive problems. Its existence was revealed – and demonstrated – in the liver damage of a patient undergoing immunosuppressive treatment. These findings were published in the journal Emerging Infectious DiseasesJanuary 3, 2023.
Analysis of pathological tissues
This patient suffered from unexplained chronic hepatitis with biological manifestations but few symptoms as is often the case in liver pathologies. Seventeen years earlier, she had received a double heart and lung transplant, with very regular monitoring. Many samples over several years were available, allowing the identification of this new virus. The doctors analyzed the samples of the pathological tissues of this patient under immunosuppressive treatment. “Ten years ago, such techniques were not available. We have also forged partnerships with the Necker hospital, thus enabling such scientific discoveries”, explains Marc Eloit, Head of the Pathogen Discovery Laboratory at the Institut Pasteur and Professor of Virology at the National Veterinary School of Alfort (EnvA).
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Indeed, these samples were sequencing for microbial sequences, a technique possible through the use of mNGS high-throughput sequencing techniques. “It’s regarding identifying interesting sequences among all the sequences obtained, a needle in a haystack! points out the researcher, in a press release issued by the Institut Pasteur. This is how scientists identified a still unknown species of circovirus, the first pathogenic circovius for humans.
A specific PCR test
Thanks to the results of this analysis, the scientists noted that the concentration of the viral genome had reached a peak in September 2021. If the patient felt only mild symptoms, damage was identified in the liver. “The multiplication of the virus in liver cells has been revealed [2 à 3 % des cellules du foie étaient infectées], demonstrating the role of HCirV-1 in liver damage: indeed, once this virus has used the resources of the liver cell to multiply, it destroys it”, note the researchers. Once these results were known, the medical team adapted the current treatment. For the moment, the origin of this virus is not yet known: “At this stage, we do not know if the contamination is between humans or in animals with an incursion in humans. Our team is still carrying out investigations to learn more regarding this virus, ”underlines the researcher.
A discovery that makes it possible to anticipate possible future epidemics, as the researcher explains: “The immunocompromised population is more fragile in the face of epidemics. It serves as a sort of sentinel once morest new viruses. Accordingly, a PCR test was developed to perform the etiological diagnosis of hepatitis of unknown origin. A serological test is also under development.
