Biology session

Recent viral metagenomic studies have shown that the family Circoviridae represents only a small part of the circular replication associated protein-encoding single stranded DNA viruses (CRESS-DNA viruses). This highly diverse clade has been detected in different eukaryotic species like plants, insects and vertebrates but in protists as well. Some bat derived CRESS-DNA viruses are members of the Circoviridae family but other viruses have also been characterized which do not cluster into this family.

The aim of our study was to explore the diversity of CRESS-DNA viruses in bats and in their preys and also discover the complex taxonomy of this diverse group. Our main question related to the bats’ own CRESS-DNA viruses. Which viruses are able to replicate in bats and which one simply pass through their digestive track?

To reveal this, we screened 392 faecal bat samples from Europe, Africa, Asia and North America. Using nested PCR we amplified 450 bp of the conserved replication associated protein-encoding gene (Rep). Among the tested samples, 110 gave a positive PCR result, and 48 from these yielded analysable partial Rep sequences. Phylogenetic analysis showed that the majority of the samples belong to the Circoviridae family: either to the Circovirus genus – we suppose these are the original CRESS-DNA viruses of the bats, or to the Cyclovirus genus – reflecting the diet of the insectivorous bats. It is hypothesised that samples clustering far from the Circoviridae family represent arthropod CRESS-DNA viruses, too.