The chicken Tva cell surface protein, a member of the low-density lipoprotein receptor family, has been identified as an entry receptor for avian leukosis virus of classic subgroup A and newly emerging subgroup K. Because both viruses represent an important concern for the poultry industry, we introduced a frame-shifting deletion into the chicken tva locus with the aim of knocking-out Tva expression and creating a virus-resistant chicken line. The tva knock-out was prepared by CRISPR/Cas9 gene editing in chicken primordial germ cells and orthotopic transplantation of edited cells into the testes of sterilized recipient roosters. The resulting tva −/− chickens tested fully resistant to avian leukosis virus subgroups A and K, both in in vitro and in vivo assays, in contrast to their susceptible tva +/+ and tva +/− siblings. We also found a specific disorder of the cobalamin/vitamin B₁₂ metabolism in the tva knock-out chickens, which is in accordance with the recently recognized physiological function of Tva as a receptor for cobalamin in complex with transcobalamin transporter. Last but not least, we bring a new example of the de novo resistance created by CRISPR/Cas9 editing of pathogen dependence genes in farm animals and, furthermore, a new example of gene editing in chicken.

A chicken multiplex cytokine assay (Bio-Plex) to detect four different cytokines (IL-2, IL-12, IL-10, and interferon gamma) simultaneously in plasma

Successful derivation and cultivation of primordial germ cells (PGCs) opened the way to efficient transgenesis and genome editing in the chicken. Furthermore, implantation of male PGCs from non-chicken galliform species into the chicken embryos resulted in cross-species germline chimeras and viable offspring. We have recently improved the PGC technology by demonstrating that chicken male PGCs transplanted into the testes of adult cockerel recipients mature into functional sperms. However, the availability of this orthotopic transplantation for cross-species transfer remains to be explored. Here we tested the capacity of genetically distant male PGCs to mature in the microenvironment of adult testes. We derived PGCs from the Chinese black-bone Silkie and transplanted them into infertile White Leghorn cockerels. Within 15–18 weeks after transplantation, we observed restoration of spermatogenesis in recipient cockerels and production of healthy progeny derived from the transplanted PGCs. Our findings also indicate the possibility of cross-species orthotopic transplantation of PGCs. Thus, our results might contribute to the preservation of endangered avian species and maintaining the genetic variability of the domestic chicken.

Systems of antigen delivery into antigen-presenting cells represent an important novel strategy in chicken vaccine development. In this study, we verified the ability of Rous sarcoma virus (RSV) antigens fused with streptavidin to be targeted by specific biotinylated monoclonal antibody (anti-CD205) into dendritic cells and induce virus-specific protective immunity. The method was tested in four congenic lines of chickens that are either resistant or susceptible to the progressive growth of RSV-induced tumors. Our analyses confirmed that the biot-anti-CD205-SA-FITC complex was internalized by chicken splenocytes. In the cytokine expression profile, several significant differences were evident between RSV-challenged progressor and regressor chicken lines. A significant up-regulation of IL-2, IL-12, IL-15, and IL-18 expression was detected in immunized chickens of both regressor and progressor groups. Of these cytokines, IL-2 and IL-12 were most up-regulated 14 days post-challenge (dpc), while IL-15 and IL-18 were most up-regulated at 28 dpc. On the contrary, IL-10 expression was significantly down-regulated in all immunized groups of progressor chickens at 14 dpc. We detected significant up-regulation of IL-17 in the group of immunized progressors. LITAF down-regulation with iNOS up-regulation was especially observed in the progressor group of immunized chickens that developed large tumors. Based on the increased expression of cytokines specific for activated dendritic cells, we conclude that our system is able to induce partial stimulation of specific cell types involved in cell-mediated immunity.

IMUNOR is an oral biotherapeutic drug that had been developed, registered, and approved in 1997 in the Czech Republic and Slovakia. IMUNOR is a dialyzable leukocyte extract (DLE) prepared from swine leukocytes. It is characterized as a mixture of small peptides with molecular weights smaller than 12 kDa and a specific portion of nucleotides. The medical uses of IMUNOR include therapeutic applications within its registered range of indications, primarily for the treatment of immunodeficiencies, allergies, and certain acute or relapsing bacterial infections in adults and children. Despite the long-term clinical application of DLE, with strong evidence of positive therapeutic effects and no serious side effects, a detailed physicochemical specification of this mixture was lacking. We developed several methods for more in-depth physicochemical characterization of IMUNOR, including a spectrophotometric method for quantification of the total protein concentration and total DNA concentration in a mixture, several chromatographic methods for identification of individual components present in significant concentrations in IMUNOR, such as HPLC methods and the Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis method, and characterization of amino acid composition of this mixture. For the investigation of the variability among different batches of IMUNOR, five to nine representative batches from a standard manufacturing process on an industrial scale were utilized. Using the analytical methods, we verified and confirmed the batch-to-batch reproducibility of the biological product IMUNOR.

Avian sarcoma and leukosis virus (ASLV), diversified into seven phylogenetically relative subgroups (A, B, C, D, E, J, and K), present as either exogenous or endogenous viruses in domestic chicken.