Avian leukosis virus (ALV), the prototypical alpharetrovirus, causes tumorigenesis, immunosuppression, and wasting disease in poultry. The ALV genus is classified into ten subgroups, which differ in their host range, cell tropism, and receptor usage. The subgroups A, B, K, and J cause significant economic losses worldwide. The most recently discovered subgroup, ALV-K, which is now widespread in China, has been shown to use the tva cell receptor and share it with ALV-A. However, the specific amino acid residues crucial for ALV-K host cell entry remain unknown. Using precise tva expression and chimeric tva receptors, we further elucidated the significance of the cysteine-rich domain in mediating interactions with both ALV-A and ALV-K. Through a comprehensive analysis of mutated tva receptor variants, we pinpointed tryptophan at position 33 (W33) as a pivotal amino acid residue essential for ALV-K virus binding and entry. Of note is the finding that the substitution of W33 induced resistance to ALV-K while preserving sensitivity to ALV-A. This study not only represents an advance in the understanding of the specificity of the tva receptor for ALV-K, but also offers a biotechnological strategy for the prevention of ALV-K infections in poultry.

• Klíčová slova
• avian leukosis virus, chicken, guineafowl, tva receptor,
• MeSH
• buněčné linie MeSH
• internalizace viru * MeSH
• kur domácí MeSH
• nemoci drůbeže virologie   MeSH
• přichycení viru * MeSH
• ptačí leukóza virologie   MeSH
• ptačí proteiny MeSH
• substituce aminokyselin MeSH
• virové receptory * genetika   metabolismus   chemie   MeSH
• virus ptačí leukózy * fyziologie   genetika   klasifikace   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ptačí proteiny MeSH
• Tva receptor MeSH Prohlížeč
• virové receptory * MeSH

Genetic editing of the germline using CRISPR/Cas9 technology has made it possible to alter livestock traits, including the creation of resistance to viral diseases. However, virus adaptability could present a major obstacle in this effort. Recently, chickens resistant to avian leukosis virus subgroup J (ALV-J) were developed by deleting a single amino acid, W38, within the ALV-J receptor NHE1 using CRISPR/Cas9 genome editing. This resistance was confirmed both in vitro and in vivo. In vitro resistance of W38-/- chicken embryonic fibroblasts to all tested ALV-J strains was shown. To investigate the capacity of ALV-J for further adaptation, we used a retrovirus reporter-based assay to select adapted ALV-J variants. We assumed that adaptive mutations overcoming the cellular resistance would occur within the envelope protein. In accordance with this assumption, we isolated and sequenced numerous adapted virus variants and found within their envelope genes eight independent single nucleotide substitutions. To confirm the adaptive capacity of these substitutions, we introduced them into the original retrovirus reporter. All eight variants replicated effectively in W38-/- chicken embryonic fibroblasts in vitro while in vivo, W38-/- chickens were sensitive to tumor induction by two of the variants. Importantly, receptor alleles with more extensive modifications have remained resistant to the virus. These results demonstrate an important strategy in livestock genome engineering towards antivirus resistance and illustrate that cellular resistance induced by minor receptor modifications can be overcome by adapted virus variants. We conclude that more complex editing will be necessary to attain robust resistance.

• MeSH
• CRISPR-Cas systémy MeSH
• editace genu MeSH
• fibroblasty virologie   metabolismus   MeSH
• kur domácí * virologie   MeSH
• kuřecí embryo MeSH
• molekulární evoluce MeSH
• nemoci drůbeže virologie   genetika   MeSH
• odolnost vůči nemocem genetika   MeSH
• proteiny virového obalu genetika   metabolismus   MeSH
• ptačí leukóza * virologie   genetika   MeSH
• virus ptačí leukózy * genetika   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• proteiny virového obalu MeSH

The Czech Republic, a part of the former Czechoslovakia, has been at the forefront of several research directions in virology, genetics and physiology [...].

• MeSH
• virologie * MeSH
• Publikační typ
• práce podpořená grantem MeSH
• úvodníky MeSH
• Geografické názvy
• Česká republika MeSH

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.

• Klíčová slova
• avian leukosis virus subgroups A/K, gene editing in chicken, tva, vitamin B12/cobalamin,
• MeSH
• editace genu MeSH
• genový knockout MeSH
• kur domácí virologie   MeSH
• kuřecí embryo MeSH
• kyselina methylmalonová krev   MeSH
• posunová mutace MeSH
• ptačí proteiny genetika   fyziologie   MeSH
• virové receptory genetika   fyziologie   MeSH
• virus ptačí leukózy klasifikace   fyziologie   MeSH
• vitamin B 12 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyselina methylmalonová MeSH
• ptačí proteiny MeSH
• Tva receptor MeSH Prohlížeč
• virové receptory MeSH
• vitamin B 12 MeSH