Gulls in Poland have been found to host diverse strains of gammacoronaviruses (gCoVs) and deltacoronaviruses (dCoVs), shedding light on the evolution and zoonotic potential of coronaviruses (CoVs). A recent study published in the journal Scientific Reports revealed that black-headed gulls (Chroicocephalus ridibundus) and common gulls (Larus canus) in Poland were found to carry five strains of gCoVs and dCoVs.
CoVs are RNA viruses that mutate rapidly due to the low fidelity of their RNA-dependent RNA polymerase machinery. This high mutation rate allows CoVs to generate multiple viral variants during short infection cycles, increasing the likelihood of host switching and zoonotic transmission.
The researchers in this study obtained whole genomic sequences of five CoV samples. Four dCoV strains were detected in black-headed gulls, while one gCoV strain was found in a common gull. These samples were subjected to next-generation sequencing, and the sequences were compared to viral genome sequences in the GenBank database using the BLAST algorithm.
The analysis revealed that the Charadriiformes subfamily of the Laridae species, which includes gulls and terns, served as the main reservoir of gCoVs and dCoVs. The genomes of these coronaviruses were relatively long, with gCoVs exceeding 26,000 nucleotides in length and dCoVs around 23,000 nucleotides.
Interestingly, the dCoVs identified in the Polish gulls showed high diversity on a genomic scale, suggesting the possibility of new serotype variants with minimal mutations in the spike (S) protein. Additionally, phylogenetic analysis revealed that one of the gCoVs closely resembled a duck coronavirus (DuCoV2714) detected in China in 2014, indicating a potential evolutionary connection between these two viruses despite low S protein homology.
The study also highlighted the ecological diversity of gulls and terns, which can be found in various regions worldwide, including marine and freshwater environments. These birds often come into close contact with humans and domesticated animals, facilitating direct viral transmission and disease spread.
The identification of gCoVs and dCoVs in Polish gulls represents a significant contribution to the understanding of CoV diversity and evolution within the Laridae family. The co-infection of these two coronaviruses in a single organism and the potential for recombination events further underscore the need to study animal reservoirs of CoVs and their zoonotic potential.
It is worth noting that porcine dCoVs, likely derived from avian dCoVs, have the ability to infect humans. Therefore, continuous research into the diversity and zoonotic potential of CoVs is crucial for public health preparedness.
This study provides valuable insights into the evolution and zoonotic potential of CoVs found in gulls in Poland, shedding light on the broader understanding of coronavirus diversity and transmission dynamics. Further research and surveillance efforts are essential to monitor the emergence of new CoV variants and mitigate potential zoonotic threats.
