Summary
A bioRxiv preprint reports a previously uncharacterised porcine adenovirus in a New Zealand high-health pig herd affected by neonatal deaths and reproductive problems. Genome sequencing placed the virus in the Mastadenovirus genus but on a distinct lineage from characterised porcine adenoviruses.
A bioRxiv preprint reports the discovery of a divergent porcine adenovirus during an investigation of disease in a 320-sow, high-health pig herd in New Zealand. The affected herd was immunologically naïve and experienced poor appetite, lethargy, diffuse skin redness, deaths among neonatal piglets and an increased number of mummified fetuses.
The researchers found abundant viral genetic material in tissues from an affected piglet and mummified fetuses. Genome reconstruction produced a 27,685-nucleotide sequence. Phylogenetic analysis placed the virus within the Mastadenovirus genus, but on a distinct lineage from previously characterised porcine adenoviruses.
The study is a preprint, so its findings have not yet undergone peer review as presented on bioRxiv.
Contents
Evidence from the herd investigation
Histopathological examination of one piglet revealed widespread intranuclear inclusion bodies in endothelial cells. These structures are associated with viral replication inside cells and, in this case, indicated a systemic viral infection rather than a process confined to one tissue.
To identify possible causes, the researchers performed total RNA sequencing on tissues from the affected piglet and mummified fetuses. This approach sequences RNA from a sample without requiring the investigators to target a specific pathogen in advance. Computational analysis of the resulting mixture of genetic material identified an adenovirus in multiple tissues, and de novo assembly was used to reconstruct its genome without relying on an existing complete reference sequence.
A porcine kobuvirus was also detected at low abundance in the piglet’s small intestine and colon. The investigators reported no other viral pathogens in the tested material. The combination of high adenovirus abundance, distribution across tissues and widespread adenoviral inclusion bodies supports an association between the virus and the outbreak.
A distinct adenovirus lineage
Porcine adenoviruses are common in domestic pigs and are generally considered low-pathogenicity viruses associated with mild or subclinical infections. The new sequence was clearly related to mastadenoviruses, a group that includes adenoviruses infecting mammals, but its position in the phylogenetic analysis separated it from all previously characterised porcine adenoviruses.
Despite its sequence divergence, the genome retained the characteristic organisation of mastadenoviruses. This combination—recognisable overall genome structure alongside substantial evolutionary distance—indicates that the virus represents a previously unrecognised porcine adenovirus lineage rather than a routine detection of a known strain.
Why the finding matters
The investigation expands the known genetic diversity of adenoviruses in pigs and connects that diversity with a disease event involving both neonatal mortality and reproductive abnormalities. The findings suggest that adenovirus lineages that have not been detected previously may have a greater role in pig disease than their current classification implies, particularly when they enter herds with little prior immune exposure.
The evidence comes from affected animals in a single New Zealand herd. The study supports an association between this virus and the outbreak, while the virus’s individual contribution to disease, its prevalence in other pig populations and the biological mechanisms behind the observed illness remain to be established.