Pathogen assessment of Galapagos landbirds reveals novel herpesviruses and adenoviruses

Galapagos landbirds are currently threatened due to the negative effects of human encroachment. At least one species has become extinct, and several have been extirpated or suffered severe population declines in the past decades. Although some avian pathogens have been described over the years, the presence and prevalence of several infectious agents that may severely impact on the health and conservation of wild and domestic birds in the archipelago remain understudied. To fill this gap, we conducted a comprehensive health assessment of Galapagos landbirds covering five islands (including protected and anthropized areas), testing for three pathogens of avian conservation concern: adenoviruses (AdV), herpesviruses (HV), and Mycoplasma spp. Oral and cloacal swabs of 421 landbirds from 14 species were tested by PCR, and positive samples were subjected to Sanger sequencing. None of the samples were positive for Mycoplasma spp. A total of 35 birds (8.31 %) tested positive for AdV, while 13 (3.09 %) were positive for HV, with higher prevalences found within the inhabited islands of Floreana and Santa Cruz, respectively. Seven main AdV nucleotide sequence types (STs) were obtained, with AdV-1, AdV-3 and AdV-5 clustering within the genus Barthadenovirus, and AdV-2, AdV-4, AdV-6 and AdV-7 grouping within the genus Aviadenovirus. Three HV STs were obtained, with HV-1 and HV-3 clustering within the genus Mardivirus, and HV-2 grouping within the genus Iltovirus. To our knowledge, this is the first molecular description of novel adenoviruses and herpesviruses in Galapagos landbirds, which will inform current and future conservation efforts in the archipelago.