A new hepatitis virus in humans

by Prof. Hervé Fleury, MD-PhD | Ventum Biotech Scientific Board Member

A new virus belonging to Circovirus has just been detected in a patient hospitalized in France. Circoviruses have a genome composed of single-stranded circular DNA; Circoviruses are found in many animals: pigs, wild boars, bats, seals, bears, mink, horses, roe deer, dogs, birds (duck, swan, pigeon, dove), fish and python.

At the farm level, it is feared in pigs where 4 types of PCV (Porcine CircoVirus) are described; In this animal, the virus induces a drop in reproduction associated with respiratory syndrome, dermatitis, nephropathy all accompanying weight loss of the animal. The most important is PCV-2 against which there are now vaccines used in the veterinary context (ranging from inactivated virus to a capsidial protein produced by a baculovirus). Infection of pig farms is observed in Europe, USA, China, Korea and South America.

The human case

This is a 61-year-old woman who had received a heart-lung transplant 17 years earlier and then developed unlabeled hepatitis (after eliminating the responsibility of hepatitis A, B, C, D, E, cytomegalovirus, and Epstein Barr virus). She was still on immunosuppressive therapy. From a liver biopsy, sequence analysis was performed by high-throughput sequencing and sequences corresponding to the capsid and replicase of a Circovirus were identified. After synthesis of specific primers of the capsid, it was then possible to follow the corresponding virus by quantitative PCR in the various blood samples of the patient (stored in a serum library). The viral load followed the increase in transaminases and thus the biochemical expression of hepatitis; transcription of the virus in hepatocytes was demonstrated (viral mRNA observed by in situ hybridization). It was from a plasma sample that the complete sequence of the virus called HCirV-1 (Human CircoVirus-1) was obtained. Its position in the phylogenetic tree of Circoviruses lies between bats and pigs. It was not possible to identify the source of contamination.

In total, one case of viral hepatitis related to a Circovirus of undetermined source in an immunocompromised patient. An observation that should not, however, suggest that this emerging virus to our knowledge has epidemic potential. A discovery that opens perspectives on cases of hepatitis not labeled as cases observed in the UK. On the other hand, it pushes once again to deepen the links between animal viruses (here the pig?) and hepatitis in humans.

References:

Pérot et al. Circovirus Hepatitis Infection in Heart-Lung Transplant Patient, France

Emerging Infectious Diseases, Volume 29, Number 2, February 2023