Identification and analysis of a novel human circovirus strain, HCirV-1-CH, in a Swiss hepatitis patient

Circoviruses were first detected in humans recently, but not outside France or China. Their pathogenic relevance and epidemiology remain obscure. Here we describe an immunocompromised 66-year-old female patient in Switzerland with sudden onset and self-limiting hepatitis, mainly characterized by elevated liver enzymes. Metagenomic NGS identified a new strain of human circovirus (HCirV-1), tentatively named HCirV-1-CH. The HCirV-1-CH genome showed 83.6% nucleotide identity with the closest known animal viral sequences (porcine circovirus 3) and x% nucleotide identity with HCirV-1-FR, recently described in France. HCirV-1 transcripts could be detected in hepatocytes, and the HCirV-1 genome was detectable in blood, stool and urine samples of this patient for at least 20 months. Our findings highlight HCirV-1 as an emerging human pathogen that can replicate in the liver and persist in susceptible patients.