West Nile Virus Lineage 2 in Free-Living Corvus cornix Birds in Poland.

The summer temperatures recorded in Poland in 2022 were among the highest in over 30 years and, combined with higher-than-expected rainfall, gave the impression of an almost tropical climate. Such climatic conditions were ideal for the transmission of vector-borne zoonotic diseases such as West Nile fever. In northeastern Poland, in the Mazowieckie region, the Polish event-based surveillance network reported increased fatalities of free-living hooded crows (Corvus corone cornix). West Nile virus (WNV) lineage 2 was identified for the first time as the etiological agent responsible for the death of the birds. WNV was detected in 17 out of the 99 (17.17%) free-living birds tested in this study. All the WNV-infected dead birds were collected in the same area and were diagnosed in September by the NVRI and confirmed by the EURL for equine diseases, ANSES, in October 2022. Unnaturally high temperatures recorded in Poland in 2022 likely favored the infection and spread of the virus in the avian population. A nationwide alert and awareness raising of blood transfusion centers and hospitals was carried out to prevent human infections by WNV.

Molecular analysis Polish isolates of goose hemorrhagic polyomavirus from geese and free-living birds.

Goose haemorrhagic polyomavirus (GHPV) is the viral agent of hemorrhagic nephritis and enteritis of geese (HNEG), a lethal disease of goose. The study describes the results of a molecular analysis Polish isolates of GHPV from geese and free-living birds based on complete VP1 gene and VP2 gene sequences. The sequences were analyzed and aligned with different GHPV isolates sequences accessible in the GenBank database. This study indicates affiliation GHPV isolates from fee-living birds and GHPV isolates circulating in Polish goose flocks and around the world to the same genetic groups, which proves their evolutionary relationship and indicates the potential role of free-living birds as a source of infections for poultry.

Serologic Survey for West Nile Virus in Wild Boars (Sus scrofa) in Poland.

Serum samples obtained from 474 wild boars (Sus scrofa) were collected from June 2017 to September 2018 from various areas of northern and southern Poland. Serum samples were examined by enzyme-linked immunosorbent assay. However, West Nile virus (WNV) antibodies were not detected. Previous studies on WNV in Poland have focused on experimental evidence and the presence of WNV antibodies in wild birds, horses, and humans, indicating a need for more surveys of domestic and wild mammals in Poland.

Whole genome sequencing of Fowl aviadenovirus A - a causative agent of gizzard erosion and ulceration, in adult laying hens.

Gizzard erosion and ulceration (GEU) caused by fowl aviadenovirus serotype 1 (FAdV-1) of the species Fowl aviadenovirus A (FAdV-A) represents an economically important problem in poultry production. The disease affects mostly young chicken broilers or layers before production. In this study, an unusual GEU outbreak in a flock of laying hens at 38weeks of age is described. The affected flock showed elevated mortality rates, with the highest number of dead birds appearing between the 39th and 40th week of life, with a subsequent reduction in laying performance and decreased total egg weight. Post-mortem examination showed the presence of erosion in multiple areas of the gizzard, with wall perforation in the proximity of the interventriculus. FAdV antibodies were detected in all examined sera with an ELISA assay. The virus was isolated from pathologically altered gizzards. PCR, subsequent sequencing and phylogenetic analysis of the partial hexon gene confirmed the presence of FAdV-A DNA. To investigate the molecular background of FAdV-A which causes GEU in adult hens, whole genome sequencing was performed on two FAdV-A strains - strain W-15, obtained from the outbreak described in this study and strain 61/11z, isolated from a GEU outbreak in 3-week-old broiler chickens in 2011. The genome size of FAdV-A W-15 is 43,849bp. Genome sequence and genome organization resembles those of the reference, apathogenic CELO strain and the newly sequenced GEU strain, 61/11z. Most amino acid changes, between CELO and GEU strains, were observed in ORF0, ORF1, ORF14, IVa2, polymerase, pIIIa, penton base and fiber-2. Analysis conducted on the translated ORFs revealed that W-15 and 61/11z are nearly identical, with the highest rate of amino acid mutations in pTP, 100K, ORF9 and ORF10. In this study, the occurrence of GEU, caused by FAdV-1 infection, in adult layer chickens and the effects of such infection on egg production parameters are described in detail. Moreover, the whole genome sequences of two pathogenic, GEU inducing FAdV-A strains have been provided and characterized for the first time, which in the future will help to pinpoint the viral factors involved in pathogenicity.