Detection of circovirus in free-ranging brown rats (Rattus norvegicus)

Area of Science:

• Veterinary Virology
• Mammalian Genetics
• Molecular Epidemiology

Background:

• Circoviruses are small, single-stranded DNA viruses with a broad host range.
• Previously, circoviruses have been identified in various animal species, including birds and mammals.
• The discovery of novel circoviruses necessitates understanding their host associations and evolutionary origins.

Purpose of the Study:

• To investigate the presence and genetic characteristics of circoviruses in brown rats from Hungary.
• To determine the phylogenetic relationship of novel rat-associated circoviruses with known circoviruses.
• To explore the potential of brown rats as a natural host for these circoviruses.

Main Methods:

• Nested PCR using primers targeting the circovirus rep gene.
• Whole-genome amplification via inverse PCR.
• Sequencing using the primer walking method.
• Phylogenetic analysis of complete replication-associated and capsid proteins.

Main Results:

• Circoviral DNA was detected in two poisoned brown rat specimens from Hungary.
• Genomic analysis revealed these novel rat viruses are sequence variations of the same virus within the genus Circovirus, closely related to a previously reported tawny owl-associated circovirus.
• Phylogenetic analysis indicated that brown rat circoviruses cluster closest to circoviruses found in predatory mammals' feces.
• Complete genome sequencing identified novel circovirus types 1 and 2 in brown rats.

Conclusions:

• Brown rats may represent the evolutionary adapted host for the newly identified brown rat circoviruses (types 1 and 2) and the previously described tawny owl-associated circovirus.
• The findings suggest a potential link between circoviruses in rats and predatory mammals.
• Further studies are required to elucidate the pathogenic and zoonotic potential of these novel circoviruses.