Gulls in the City: Unseen Viral Passengers

The black-headed gull is a familiar sight in Hungary, often seen nesting and feeding in urban areas. This adaptability makes them interesting subjects for studying how viruses might jump between species. Between 2014 and 2018, scientists collected seven fecal samples from these gulls as part of a broader bird monitoring program. One sample, labeled MR04, was picked for a deeper look using advanced genetic sequencing techniques. The results were intriguing. Most of the viral material in the sample belonged to a family of viruses called Seadornaviridae, with a smaller portion classified under Astroviridae. This finding was confirmed using a method called RT-PCR. The study then focused on the complete genome of a potential new rotavirus strain and parts of a novel avian nephritis virus strain found in the sample. The rotavirus strain, named gull/MR04_RV/HUN/2014, showed a mix of genetic material from different rotavirus species. This mix, known as reassortment, is a common way viruses evolve and adapt. The strain was closely related to rotavirus G (RVG) in some parts of its genome but more similar to human rotavirus B (RVB) in others. This suggests that the virus might have picked up genetic material from both types, possibly through interactions with other infected species. The avian nephritis virus strain, gull/MR04_AAstV/HUN/2014, belonged to a group called Avastrovirus species avastrovirus 2 (AAstV-2). It was related to group 6 of avian nephritis viruses (ANVs), but its genetic differences hinted that it might represent a new, separate group. Further samples from other gulls tested negative for these viruses, but this doesn't mean they aren't out there. Gulls, with their urban lifestyle, could potentially spread viruses that affect both humans and other animals. However, more research is needed to fully understand the viral communities these birds carry. This is especially important for species that, like the black-headed gull, have adapted to live close to humans. Understanding these viral dynamics can help in predicting and preventing potential outbreaks.