Detection of DNA Viruses in Free-Ranging Rat Populations in Hungary

To address a gap in our understanding of viral infections in epidemiologically important rat species, we aimed to detect DNA viruses from the tissues of free-ranging rat populations in Hungary. DNA viruses were identified from the parenchymal organs of 230 Rattus norvegicus and Rattus rattus, using family-specific pan-PCR assays followed by sequencing of the PCR products. Adeno-, herpes-, circo-, and polyomaviruses were detected, while irido-, pox-, and dependoparvoviruses were not. Adenovirus DNA was present in 6.5% of the samples, herpesvirus and polyomavirus DNA in 12.2%, and circovirus DNA in 1.7%. All detected herpesviruses belonged to the β and γ subfamilies, with a majority being β herpesviruses. Some adenovirus and herpesvirus sequences were novel, while only the known Rattus norvegicus polyomavirus 1 was detected for polyomaviruses. The rare circovirus-positive samples revealed the presence of both rodent and bird circoviruses, indicating the ability of circoviruses to cross species barriers. Our findings show that rats host a variety of DNA viruses, many of which were previously uncharacterized, highlighting the need for further diagnostic studies.