Effect of Mycoplasma synoviae strains isolated from the respiratory and reproductive tracts of chicken on SPF chicken embryos

Mycoplasma synoviae (MS) infections in poultry are an important epidemiological and economic problem in poultry production all over the world. The differences between M. synoviae strains are related to the pathogenicity and the course of the disease. In recent years, the pathogenicity of M. synoviae strains has increased, and some of them are capable of causing serious infections. Both horizontal and vertical transmission routes play an important role in MS infection in flocks. The aim of the study was to determine the impact of infection with selected MS strains obtained from chickens showing a clinical form of MS infection on SPF chicken embryos. Ten strains of M. synoviae were used for this purpose. The strains were isolated from the respiratory tract and the oviduct of chickens with symptoms typical of infection with this pathogen. Genetic material isolated from liquid cultures of these strains was confirmed by molecular (PCR and LAMP) and microbiological methods. The selected M. synoviae strains belonged to six different genotypes. Significant differences in virulence between the strains were demonstrated. In nine infected groups of embryos, M. synoviae strains caused weight loss, and in seven groups they produced anatomopathological changes characteristic of mycoplasma infections. The most pathogenic for SPF chicken embryos turned out to be strains characterized as genotype F isolated from the chicken oviduct and strains of genotype C isolated from the respiratory tract. One strain of genotype H isolated from the respiratory tract showed no pathogenic effect on SPF chicken embryos. The study showed that infections with M. synoviae can have a significant impact on the production of chicken chicks in commercial hatcheries and the economy of the poultry industry.

HMEJ-mediated efficient site-specific gene integration in chicken cells

Background The production of transgenic chicken cells holds great promise for several diverse areas, including developmental biology and biomedical research. To this end, site-specific gene integration has been an attractive strategy for generating transgenic chicken cell lines and has been successfully adopted for inserting desired genes and regulating specific gene expression patterns. However, optimization of this method is essential for improving the efficiency of genome modification in this species. Results Here we compare gene knock-in methods based on homology-independent targeted integration (HITI), homology-directed repair (HDR) and homology mediated end joining (HMEJ) coupled with a clustered regularly interspaced short palindromic repeat associated protein 9 (CRISPR/Cas9) gene editing system in chicken DF-1 cells and primordial germ cells (PGCs). HMEJ was found to be a robust and efficient method for gene knock-in in chicken PGCs. Using this method, we successfully labeled the germ cell specific gene DAZL and the pluripotency-related gene Pou5f3 in chicken PGCs through the insertion of a fluorescent protein in the frame at the 3′ end of the gene, allowing us to track cell migration in the embryonic gonad. HMEJ strategy was also successfully used in Ovalbumin, which accounts for more than 60% of proteins in chicken eggs, suggested its good promise for the mass production of protein with pharmaceutical importance using the chicken oviduct system. Conclusions Taken together, these results demonstrate that HMEJ efficiently mediates site-specific gene integration in chicken PGCs, which holds great potential for the biopharmaceutical engineering of chicken cells.