Molecular surveillance of adenovirus and coronavirus in Procellariiformes, Brazil: Detection of new divergent adenoviruses.

Adenoviruses are widespread DNA viruses that infect a broad range of vertebrate hosts and are recognized for their long-term host coevolution, remarkable genetic diversity, and broad pathogenic potential. Coronaviruses circulate among wild birds due to their evolutionary potential and are relevant to animal and public health. However, the diversity and ecological role of these viruses in pelagic seabirds remain poorly understood. This study provides the first molecular survey of adenoviruses and coronaviruses in Procellariiformes from the South Atlantic. Fifty stranded individuals representing 12 Procellariiformes species were collected along the southeastern Brazilian coast, between 2017 and 2023. Adenovirus and coronavirus survey were performed using nested PCR protocols, followed by sequencing, phylogenetic analysis, and histopathology of positive cases. Adenovirus was detected in seven individuals (14%; 95% CI: 5.8-26.7%) from three species: Southern Giant Petrels (Macronectes giganteus), Cory's Shearwaters (Calonectris borealis), and Black-browed Albatrosses (Thalassarche melanophris). Five sequence types were identified, including similar variants in Southern Giant Petrels and distinct adenoviruses in Cory's Shearwaters and Black-browed Albatrosses. All viruses clustered within a divergent lineage with adenoviruses previously detected in New Zealand seabirds and a Chimney Swift from the USA. No intranuclear inclusion bodies were found in histopathological analysis. All specimens were coronavirus-negative. This first molecular detection of adenoviruses in Procellariiformes expands the known diversity and host range of seabird adenoviruses and suggests circulation of genetically distinct viruses across oceanic regions, highlighting the need for genomic and epidemiological studies of their evolution, transmission, and health impacts.