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Avian influenza viruses (AIV) of wild ducks are known to be able to sporadically infect domestic birds and spread along poultry. Regular surveillance of AIV in the wild is needed to prepare for potential outbreaks. During long-year monitoring, 46 strains of AIV were isolated from gulls and mallards in Moscow ponds and completely sequenced. Amino acid positions that affect the pathogenicity of influenza viruses in different hosts were tested. The binding affinity of the virus for receptors analogs typical for different hosts and the pathogenicity of viruses for mice and chickens were investigated. Moscow isolates did not contain well-known markers of pathogenicity and/or adaptation to mammals, so as a polybasic cleavage site in HA, substitutions of 226Q and 228G amino acids in the receptor-binding region of HA, and substitutions of 627E and 701D amino acids in the PB2. The PDZ-domain ligand in the NS protein of all studied viruses contains the ESEV or ESEI sequence. Although several viruses had the N66S substitution in the PB1-F2 protein, all Moscow isolates were apathogenic for both mice and chickens. This demonstrates that the phenotypic manifestation of pathogenicity factors is not absolute but depends on the genome context.

Forty-five strains of AIVs were isolated from wild aquatic birds during their autumn migration through Moscow (Russia). The aim of this work is to study the dynamics of AIV genomes in their natural habitat. Viruses were isolated from fecal sample in embryonated chicken eggs; their complete genomes were sequenced, and a phylogenetic analysis was performed. The gene segments of the same lineage persisted over the years in the absence of persistence of complete viral genomes. The genes for internal proteins of the same lineage were often maintained by the viruses over few years; however, they were typically associated with the genes of novel HA and NA subtypes. Although frequent reassortment events were observed for any pair of internal genes, there was no reassortment between HA and NA segments. The differences in the persistence of phylogenetic lineages of surface and internal proteins and the different evolutionary strategy for these two types of genes of AIVs in primary hosts are discussed.

The concerns regarding microplastics and nanoplastics pollution stimulate studies on the uptake and biodistribution of these emerging pollutants in vitro. Atomic force microscopy in nanomechanical PeakForce Tapping mode was used here to visualise the uptake and distribution of polystyrene spherical microplastics in human skin fibroblast. Particles down to 500 nm were imaged in whole fixed cells, the nanomechanical characterization allowed for differentiation between internalized and surface attached plastics. This study opens new avenues in microplastics toxicity research.