No abstract

Innate antiviral immunity establishes first line of defense against invading pathogens through sensing their molecular structures such as viral RNA. This antiviral potential of innate immunity is mainly attributed to a myriad of IFN-stimulated genes (ISGs). Amongst well-characterized ISGs, we have previously shown that antiviral potential of chicken IFN-induced proteins with tetratricopeptides repeats 5 (chIFIT5) is determined by its interaction potential with 5′ppp containing viral RNA. Here, we generated transgenic chickens using avian sarcoma-leukosis virus (RCAS)-based gene transfer system that constitutively and stably express chIFIT5. The transgenic chickens infected with clinical dose (EID50 104 for HPAIV and 105 EID50 for vNDV) of high pathogenicity avian influenza virus (HPAIV; H5N1) or velogenic strain of Newcastle disease virus (vNDV; Genotype VII) showed marked resistance against infections. While transgenic chickens failed to sustain a lethal dose of these viruses (EID50 105 for HPAIV and 106 EID50 for vNDV), a delayed and lower level of clinical disease and mortality, reduced virus shedding and tissue damage was observed compared to non-transgenic control chickens. These observations suggest that stable expression of chIFIT5 alone is potentially insufficient in providing sterile protection against these highly virulent viruses; however, it is sufficient to ameliorate the clinical outcome of these RNA viruses. These findings propose the potential of innate immune genes in conferring genetic resistance in chickens against highly pathogenic and zoonotic viral pathogens causing sever disease in both animals and humans.

In the last 5 years, frequent outbreaks of infectious bronchitis virus (IBV) are observed in both broiler and layer chicken flocks in the Kingdom of Saudi Arabia (KSA) in spite of extensive usage of vaccines. The IBV is a widespread avian coronavirus affecting both vaccinated and unvaccinated chicken flocks and is attributed to significant economic losses, around the globe. In the present study, 58 (n = 58) samples were collected from four different commercial poultry flocks from 8 KSA districts during 2019. A total of nine positive isolates (9/58; 15.5%), based on real-time reverse transcriptase PCR targeting nucleocapsid (N) gene, were used for further genetic characterization and evolutionary analysis. Genetic characterization of the partial spike (S1) gene revealed the clustering of the reported isolates into three different genotypes, whereas four additional isolates were grouped within 4/91 genotype, two isolates within IS/885 genotype, one isolate was closely related to IS/1494/06, and two isolates were grouped within classic serotype (vaccine-like strains). Phylodynamic revealed clustering of four isolated viruses within GI-13 lineage, three isolates within GI-23 lineage, and two isolates within GI-1 lineage. Results indicate that there are high evolutionary distances between the newly identified IBV strains in this study and the commercially used vaccines (GI-1), suggesting that IBV strains circulating in the KSA are under constant evolutionary pressures. Selective pressure biostatistics analyses consistently demonstrate the presence of a higher positive score which highlights the role of natural selection, a mechanism of virus evolution on sites located on the protein surface, within or nearby domains involved in viral attachment or related functions. Recombination analysis revealed emergence of two isolates through recombination events resulting in new recombinant viruses. Taken together, these finding demonstrate the genetic and evolutionary insights into the currently circulating IBV genotypes in KSA, which could help to better understand the origin, spread, and evolution of infectious bronchitis viruses, and to ascertain the importance of disease monitoring as well as re-evaluation for the currently used vaccines and vaccination programs.

Transmission of viruses from the commercial poultry to wild birds is an emerging paradigm of livestock-wildlife interface. Here, we report the identification and isolation of vaccine strains of avian paramyxovirus serotype 1 (APMV1) and avian coronaviruses (ACoV) from different wild bird species across eight Egyptian governorates between January 2014 and December 2015. Surveillance of avian respiratory viruses in free-ranging wild birds (n=297) identified three species that harboured or excreted APMV1 and ACoVs. Genetic characterization and phylogenetic analysis of recovered viruses revealed a close association with the most widely utilized vaccine strains in the country. These results highlight the potential spillover of vaccine-viruses probably due to extensive use of live-attenuated vaccines in the commercial poultry, and close interaction between domesticated and wild bird populations. Further exploring the full spectrum of vaccine-derived viral vaccine strains in wild birds might help to assess the emergence of future wild-birds origin viruses.