Most cited article - PubMed ID 28607078
Retroviral host range extension is coupled with Env-activating mutations resulting in receptor-independent entry
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 Systems MeSH
- Gene Editing MeSH
- Fibroblasts virology metabolism MeSH
- Chickens * virology MeSH
- Chick Embryo MeSH
- Evolution, Molecular MeSH
- Poultry Diseases virology genetics MeSH
- Disease Resistance genetics MeSH
- Viral Envelope Proteins genetics metabolism MeSH
- Avian Leukosis * virology genetics MeSH
- Avian Leukosis Virus * genetics physiology MeSH
- Animals MeSH
- Check Tag
- Chick Embryo MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Viral Envelope Proteins MeSH
It has now been more than two years since we said our last goodbye to Jan Svoboda (14 [...].
Avian leukosis virus subgroup K (ALV-K) is composed of newly emerging isolates, which, in sequence analyses, cluster separately from the well-characterized subgroups A, B, C, D, E, and J. However, it remains unclear whether ALV-K represents an independent ALV subgroup with regard to receptor usage, host range, and superinfection interference. In the present study, we examined the host range of the Chinese infectious isolate JS11C1, an ALV-K prototype, and we found substantial overlap of species that were either resistant or susceptible to ALV-A and JS11C1. Ectopic expression of the chicken tva gene in mammalian cells conferred susceptibility to JS11C1, while genetic ablation of the tva gene rendered chicken DF-1 cells resistant to infection by JS11C1. Thus, tva expression is both sufficient and necessary for JS11C1 entry. Receptor sharing was also manifested in superinfection interference, with preinfection of cells with ALV-A, but not ALV-B or ALV-J, blocking subsequent JS11C1 infection. Finally, direct binding of JS11C1 and Tva was demonstrated by preincubation of the virus with soluble Tva, which substantially decreased viral infectivity in susceptible chicken cells. Collectively, these findings indicate that JS11C1 represents a new and bona fide ALV subgroup that utilizes Tva for cell entry and binds to a site other than that for ALV-A.IMPORTANCE ALV consists of several subgroups that are particularly characterized by their receptor usage, which subsequently dictates the host range and tropism of the virus. A few newly emerging and highly pathogenic Chinese ALV strains have recently been suggested to be an independent subgroup, ALV-K, based solely on their genomic sequences. Here, we performed a series of experiments with the ALV-K strain JS11C1, which showed its dependence on the Tva cell surface receptor. Due to the sharing of this receptor with ALV-A, both subgroups were able to interfere with superinfection. Because ALV-K could become an important pathogen and a significant threat to the poultry industry in Asia, the identification of a specific receptor could help in the breeding of resistant chicken lines with receptor variants with decreased susceptibility to the virus.
- Keywords
- Tva, avian leukosis virus K, host range, resistance/susceptibility to retrovirus, retrovirus receptor, superinfection interference,
- MeSH
- Cell Line MeSH
- Species Specificity MeSH
- Fibroblasts cytology metabolism virology MeSH
- Virus Internalization MeSH
- Mesocricetus MeSH
- Chickens MeSH
- Disease Susceptibility MeSH
- Avian Leukosis genetics metabolism virology MeSH
- Avian Proteins genetics metabolism MeSH
- Receptors, Virus genetics metabolism MeSH
- Avian Leukosis Virus classification pathogenicity physiology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Avian Proteins MeSH
- Tva receptor MeSH Browser
- Receptors, Virus MeSH
