An in vitro validation system for chicken bioreactors using immortalized chicken oviductal epithelial cells.

The utilization of chicken oviductal epithelial cells (OECs) as a bioreactor to produce therapeutic proteins has shown promise, but the time taken to obtain transgenic offspring impedes efficient validation of protein production. To overcome this barrier, we focused on the immortalization of chicken OECs (cOECs) using retroviral vector-mediated c-MYC oncogene expression to establish an in vitro pre-validation system for chicken bioreactors. The resulting immortalized cOECs exhibited sustained proliferation, maintained a normal diploid chicken karyotype, and expressed key oviduct-specific genes (OVA, OVM, LYZ, AVD, and ESR1). Notably, hormonal administration of diethylstilbestrol (DES) or progesterone (P4) upregulated oviduct-specific genes in these cells. To enhance the utility of these immortalized cOECs as an in vitro validation system for chicken bioreactors, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology was employed to knock-in (KI) an enhanced green fluorescence protein (EGFP) gene at the ovalbumin (OVA) locus. The resulting OVA EGFP KI immortalized cOECs secreted both EGFP and OVA proteins into the culture medium, with secretion enhanced under DES treatment. This successful integration of an exogenous gene into cOECs enhances their potential as a versatile in vitro validation system for chicken bioreactors. The established immortalized cOECs overcome previous challenges associated with long-term culture and maintenance, providing a reliable platform for efficient protein production validation. This study presents a comprehensive characterization of the immortalized cOECs, addressing critical limitations associated with in vivo systems and laying a foundation for the development of a streamlined and effective chicken bioreactor model.

Efficacy of part-time patching in preventing recurrence after bilateral lateral rectus recession in children with intermittent exotropia.

BACKGROUND: This study evaluate the efficacy of part-time patching in preventing recurrence after bilateral lateral rectus recession (BLR) in patients with intermittent exotropia (IXT). METHODS: A total of 190 children aged 3-13 years who experienced recurrence after BLR for IXT and received part-time patching were retrospectively reviewed. The patching was prescribed for 2 h per day for more than 6 months. Patients who had a recurrence of 18 PD or more underwent reoperation. Changes in exodeviation and reoperation ratio after part-time patching were analyzed. RESULTS: A total of 34 patients (17.9%) received reoperation after part-time patching, and the reoperation ratio after 2 years was 20.3% as per the Kaplan-Meier survival analysis. Patients with a recurrence of 7 to 10 PD showed a significantly better effect compared to those with a recurrence of more than 10 PD (p < 0.001), and the reoperation ratio was also lower in the survival analysis (p = 0.004). The factor associated with reoperation in patients with part-time patching was the duration between the operation and the initiation of part-time patching (hazard ratio [HR] = 1.006, p = 0.002). CONCLUSIONS: Part-time patching was effective in maintaining the efficacy of surgery and delaying the need of reoperation after BLR. This effect was better in patients with a recurrence of ≤ 10 PD.

Primary and additional treatment preference in aggressive retinopathy of prematurity and type 1 retinopathy of prematurity.

OBJECTIVE: This study aimed to evaluate the preference for antivascular endothelial growth factor (anti-VEGF) versus laser ablation therapy as primary and additional treatment in aggressive retinopathy of prematurity (ROP) and type 1 ROP. METHODS: This multicentre retrospective study was conducted at nine medical centres across South Korea. A total of 94 preterm infants with ROP who underwent primary treatment between January 2020 and December 2021 were enrolled. All eyes were classified as having type 1 ROP or aggressive ROP. Data on the zone, primary treatment chosen, injection dose, presence of reactivation and additional treatment were collected and analysed. RESULTS: Seventy infants (131 eyes) with type 1 ROP and 24 infants (45 eyes) with aggressive ROP were included. Anti-VEGF injection was selected as the primary treatment in 74.05% of the infants with type 1 ROP and 88.89% with aggressive ROP. Anti-VEGF injection was selected as the ROP was located in zone I or posterior zone II, and laser ablation was selected when it was located in zone II. The anti-VEGF injection doses varied and tended to be higher in the aggressive ROP group. Infants with aggressive ROP were 2.08 times more likely to require additional treatment than those with type 1 ROP. When ROP reactivation occurred, laser therapy was preferred as an additional treatment. CONCLUSION: In Korea, the preference for anti-VEGF therapy or laser therapy differed according to ROP subtype, zone and primary or secondary treatment. These findings suggest that ROP treatment are considered according to ROP subtype, location and reactivation.

Correlation between bilateral lateral rectus muscle recession and myopic progression in children with intermittent exotropia.

Although several studies have reported about the relationship between the surgical correction of intermittent exotropia and myopic progression, it remains unclear, unlike the relationship between esotropia and hyperopia. Thus, this retrospective case control study evaluated the impact of bilateral lateral rectus recession in intermittent exotropia on myopic progression. This study included 388 patients with intermittent exotropia. The refractive errors and degree of exodeviation at each follow up period were analyzed. The rate of myopic progression was -0.46 ± 0.62 diopter (D)/year in patients who underwent surgery and -0.58 ± 0.78 D/year in patients who did not, with no significant difference between them (p = 0.254). Patients who had recurrences of more than 10 prism diopters were compared with patients who did not have. The rate of myopic progression was -0.57 ± 0.72 D/year in the recurrent group and -0.44 ± 0.61 D/year in the non-recurrent group, with no significant difference between them (p = 0.237). Patients with fast myopic progression had more recurrence than patients with slow progression (p = 0.042). Moreover, recurrence had a positive correlation with fast myopic progression (OR = 2.537, p = 0.021). Conclusively, the surgical correction of intermittent exotropia did not influence myopic progression.

Female Germ Cell Development in Chickens and Humans: The Chicken Oocyte Enriched Genes Convergent and Divergent with the Human Oocyte.

The development of germ cells and other physiological events in the differentiated ovary of humans are highly conserved with several mammalian species, except for the differences in timing. However, comparative knowledge on this topic is very scarce with respect to humans and lower vertebrates, such as chickens. In chickens, female germ cells enter into meiosis around embryonic day (E) 15.5 and are arrested in meiotic prophase I as primary oocytes. The oocytes arrested in meiosis I are accumulated in germ-cell cysts; shortly after hatching, they are enclosed by flattened granulosa cells in order to form primordial follicles. In humans, the process of meiotic recombination in female germ cells begins in the 10-11th week of gestation, and primordial follicles are formed at around week 20. In this review, we comprehensively elucidate both the conservation and the species-specific differences between chickens and humans with respect to germ cell, oocyte, and follicle development. Importantly, we provide functional insights into a set of chicken oocyte enriched genes (from E16 to 1 week post-hatch) that show convergent and divergent expression patterns with respect to the human oocyte (from week 11 to 26).

Generation and characterization of genome-modified chondrocyte-like cells from the zebra finch cell line immortalized by c-MYC expression.

BACKGROUND: Due to their cost effectiveness, ease of use, and unlimited supply, immortalized cell lines are used in place of primary cells for a wide range of research purposes, including gene function studies, CRISPR-based gene editing, drug metabolism tests, and vaccine or therapeutic protein production. Although immortalized cell lines have been established for a range of animal species, there is still a need to develop such cell lines for wild species. The zebra finch, which is used widely as a model species to study the neurobiological basis of human speech disorders, has been employed in several functional studies involving gene knockdown or the introduction of exogenous transgenes in vivo; however, the lack of an immortalized zebra finch cell line has hampered precise genome editing studies. RESULTS: Here, we established an immortalized cell line by a single genetic event, expression of the c-MYC oncogene, in zebra finch embryonic fibroblasts and examined its potential suitability for gene targeting investigations. Retroviral vector-mediated transduction of c-MYC was used to immortalize zebra finch primary fibroblasts; the transformed cells proliferated stably over several passages, resulting in the expression of chondrocyte-specific genes. The transfection efficiency of the immortalized cells was much higher than that of the primary cells. Targeted knockout of the SOX9 gene, which plays a role in the differentiation of mesenchymal progenitor cells into chondrocytes, was conducted in vitro and both apoptosis and decreased expression levels of chondrogenic marker genes were observed in edited cells. CONCLUSIONS: The c-MYC induced immortalized chondrocyte-like cell line described here broadens the available options for establishing zebra finch cell lines, paves the way for in-depth biological researches, and provides convenient approaches for biotechnology studies, particularly genomic modification research.

Amplification of immunity by engineering chicken MDA5 combined with the C terminal domain (CTD) of RIG-I.

Innate immune system is triggered by pattern recognition receptors (PRRs) recognition. Retinoic acid-inducible gene 1 (RIG-I) is a major sensor that recognizes RNA ligands. However, chickens have no homologue of RIG-I; instead, they rely on melanoma differentiation-associated protein 5 (MDA5) to recognize RNA ligands, which renders chickens susceptible to infection by influenza A viruses (IAVs). Here, we engineered the cMDA5 viral RNA sensing domain (C-terminal domain, CTD) such that it functions similarly to human RIG-I (hRIG-I) by mutating histidine 925 into phenylalanine, a key residue for hRIG-I RNA binding loop function, or by swapping the CTD of cMDA5 with that of hRIG-I or duck RIG-I (dRIG-I). The engineered cMDA5 gene was expressed in cMDA5 knockout DF-1 cells, and interferon-beta (IFN-ß) activity and expression of interferon-related genes were measured after transfection of cells with RNA ligands of hRIG-I or human MDA5 (hMDA5). We found that both mutant cMDA5 and engineered cMDA5 triggered significantly stronger interferon-mediated immune responses than wild-type cMDA5. Moreover, engineered cMDA5 reduced the IAV titer by 100-fold compared with that in control cells. Collectively, engineered cMDA5/RIG-I CTD significantly enhanced interferon-mediated immune responses, making them invaluable strategies for production of IAV-resistant chickens. KEY POINTS: • Mutant chicken MDA5 with critical residue of RIG-I (phenylalanine) enhanced immunity. • Engineered chicken MDA5 with CTD of RIG-I increased IFN-mediated immune responses. • Engineered chicken MDA5 reduced influenza A virus titers by up to 100-fold.

Colon Polyp Detection in Primary Health Care Institutions of Korea: Detection Rate and Issues with Following the Guidelines.

Background/Aims: There have been few multicenter studies on colonic polyps conducted by primary medical institutions. This study examined the detection rate of colonic polyps in primary health care institutions and the related factors while following the guidelines. Methods: The medical records of 14,029 patients who underwent colonoscopy between January-June 2020 at 40 primary medical institutions in Korea were analyzed. High-risk adenoma was defined as advanced adenoma, carcinoma, or ≥3 adenomas. Results: Most patients (71.2%) aged ≥50 years underwent re-colonoscopy within 5 years (51.3%) for diagnostic purposes (61.3%) in Korean primary medical institutions. The detection rates of colon polyps, adenoma, advanced adenoma, high-risk adenoma, and carcinoma was 59.9%, 38.9%, 5.9%, 11.4%, and 0.3% in all subjects and 59.8%, 37.5%, 8.5%, 12.9%, and 0.3% in average-risk patients, respectively. The incidences of adenoma in average-risk patients increased significantly with age (30s/40s/50s: 20.1%/29.4%/43% for adenoma, 4.4%/6.7%/10.3% for advanced adenoma, and 5.6%/9.5%/14.6% for high-risk adenoma; p<0.05). Before 50 years of age, high-risk adenoma was detected in 9.1% of patients in the first-time screening group, and the significant risk factors were being male and ≥40 years of age. The detection rate of high-risk adenoma in the normal index colonoscopy group within 5 years was 9.0%. The significant risk factors included older age, male sex, positive fecal occult blood test, stool form changes, and nonspecific symptoms (gas and indigestion). Conclusions: More colonic adenoma studies targeting real-world clinical practice will be needed to revise the Korean guidelines for colorectal cancer screening and surveillance.

Efficient gene transfer into zebra finch germline-competent stem cells using an adenoviral vector system.

Zebra finch is a representative animal model for studying the molecular basis of human disorders of vocal development and communication. Accordingly, various functional studies of zebra finch have knocked down or introduced foreign genes in vivo; however, their germline transmission efficiency is remarkably low. The primordial germ cell (PGC)-mediated method is preferred for avian transgenic studies; however, use of this method is restricted in zebra finch due to the lack of an efficient gene transfer method for the germline. To target primary germ cells that are difficult to transfect and manipulate, an adenovirus-mediated gene transfer system with high efficiency in a wide range of cell types may be useful. Here, we isolated and characterized two types of primary germline-competent stem cells, PGCs and spermatogonial stem cells (SSCs), from embryonic and adult reproductive tissues of zebra finch and demonstrated that genes were most efficiently transferred into these cells using an adenovirus-mediated system. This system was successfully used to generate gene-edited PGCs in vitro. These results are expected to improve transgenic zebra finch production.

Pachydrusen, choroidal vascular hyperpermeability, and punctate hyperfluorescent spots.

PURPOSE: To investigate the relationship between pachydrusen and features of choroidal vascular hyperpermeability (CVH) and punctate hyperfluorescent spots (PHS) on serial imaging in patients with polypoidal choroidal vasculopathy (PCV) or pachychoroid neovasculopathy (PNV). METHODS: Patients diagnosed between January 2007 and June 2016 at 2 high-volume, tertiary hospitals were retrospectively reviewed with serial multimodal imaging assessment. The primary outcome was the association between drusen subtypes (hard/soft drusen, subretinal drusenoid droplets, or pachydrusen) with CVH and PHS, previously described in central serous chorioretinopathy. RESULTS: Among the 105 eyes (105 patients; mean age, 67.0 years), 87 (82.9%) were diagnosed with PCV and 18 (17.1%) with PNV. Pachydrusen was the most frequently identified subtype (54 eyes, 51.4%). CVH (72.2% vs 41.4%, P = 0.021) and PHS (72.2% vs 44.8%, P = 0.041) were observed with greater frequency in PNV eyes. Significant correlations were found between CVH and PHS (phi coefficient φ 0.30, P = 0.003), and PHS with pachydrusen (φ 0.20, P = 0.040). Over a mean follow-up of 74.8 months, new drusen co-localizing to PHS were noted in 22 (21.0%) eyes (φ 0.54, P < 0.001). CONCLUSION: We observed a trend of pachydrusen appearing in conjunction with PHS in PCV or PNV. Frequent localization of new drusen to these choroidal lesions was observed over long-term follow-up. PHS may be a form of late-staining "forme fruste" drusen, possibly associated with micro-ischemic changes to the choriocapillaris.

Long-term surgical outcomes of primary retropupillary iris claw intraocular lens implantation for the treatment of intraocular lens dislocation.

We aimed to investigate the efficacy and safety of primary retropupillary iris claw intraocular lens (R-IOL) implantation in patients with complete intraocular lens (IOL) dislocation. In this single-center retrospective case series, we reviewed the medical records of patients who underwent R-IOL implantation surgery with pars plana vitrectomy for the treatment of IOL dislocation between September 2014 and July 2019. The primary outcome was change in visual acuity (VA) up to 24 months postoperatively. The secondary outcomes included changes in intraocular pressure (IOP), refractive errors, and endothelial cell count (ECC) over the same period. Data of 103 eyes (98 patients) were analyzed. The mean uncorrected VA was significantly improved at one month postoperatively (- 0.69 logMAR, P < 0.001), compared to the preoperative value. IOP (- 2.3 mmHg, P = 0.008) and ECC (- 333.4 cells/mm2, P = 0.027) significantly decreased one month post-surgery and remained stable thereafter. Postoperative mean spherical equivalents were similar to the prediction error throughout the follow-up period. IOP elevation (n = 8, 7.8%), cystoid macular edema (n = 4, 3.9%), and dislocation of the R-IOL (n = 10, 9.7%) were managed successfully. Overall, primary R-IOL implantation with pars plana vitrectomy is effective and safe for correcting IOL dislocation due to various causes.

Production of quail (Coturnix japonica) germline chimeras by transfer of Ficoll-enriched spermatogonial stem cells.

Due to the absence of long-term in vitro germline competent stem cell maintenance systems and efficient methods for germline transmission, efforts to develop an effective transgenic system in quail has remained limited. To overcome this limitation, here we produced germline chimeric quails through transplantation of spermatogonial stem cells (SSCs) enriched by density gradient methods utilizing Ficoll-Paque PLUS (Ficoll), Percoll and sucrose solution as a practical strategy for germline transmission in quail. For all gradient methods, testicular cells were separated as two fractions, and the expression levels of SSC-specific genes (GFRA1, ITGA6, ITGB1) and pluripotency genes (NANOG, POUV) were examined. As a result, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and RNA probe hybridization analysis revealed that the upper fraction that was separated by Ficoll showed the highest expression of SSC-specific and pluripotency genes among all fractions. Cells in the upper Ficoll gradient fraction also displayed reduced heterochromatin distribution, as observed in differentiated spermatogonia using transmission electron microscopy (TEM). These results indicate that SSCs were enriched in the upper fraction by Ficoll density gradient centrifugation. Subsequent transplantation experiments revealed that the efficiency of germline transmission to donor-derived gametes in the germline chimeras with transplanted SSCs and whole testicular cells was 0-13.2% and 0-4.4%, respectively. Collectively, these results demonstrate that quail SSCs were easily enriched with a density gradient method and that this method is a feasible and practical way to preserve the germplasm of quail. Furthermore, we can expect to apply this method in research examining the production of transgenic quail and preservation of avian species.

Targeted Knockout of MDA5 and TLR3 in the DF-1 Chicken Fibroblast Cell Line Impairs Innate Immune Response Against RNA Ligands.

The innate immune system, which senses invading pathogens, plays a critical role as the first line of host defense. After recognition of foreign RNA ligands (e.g., RNA viruses), host cells generate an innate immune or antiviral response via the interferon-mediated signaling pathway. Retinoic acid-inducible gene I (RIG-1) acts as a major sensor that recognizes a broad range of RNA ligands in mammals; however, chickens lack a RIG-1 homolog, meaning that RNA ligands should be recognized by other cellular sensors such as melanoma differentiation-associated protein 5 (MDA5) and toll-like receptors (TLRs). However, it is unclear which of these cellular sensors compensates for the loss of RIG-1 to act as the major sensor for RNA ligands. Here, we show that chicken MDA5 (cMDA5), rather than chicken TLRs (cTLRs), plays a pivotal role in the recognition of RNA ligands, including poly I:C and influenza virus. First, we used a knockdown approach to show that both cMDA5 and cTLR3 play roles in inducing interferon-mediated innate immune responses against RNA ligands in chicken DF-1 cells. Furthermore, targeted knockout of cMDA5 or cTLR3 in chicken DF-1 cells revealed that loss of cMDA5 impaired the innate immune responses against RNA ligands; however, the responses against RNA ligands were retained after loss of cTLR3. In addition, double knockout of cMDA5 and cTLR3 in chicken DF-1 cells abolished the innate immune responses against RNA ligands, suggesting that cMDA5 is the major sensor whereas cTLR3 is a secondary sensor. Taken together, these findings provide an understanding of the functional role of cMDA5 in the recognition of RNA ligands in chicken DF-1 cells and may facilitate the development of an innate immune-deficient cell line or chicken model.

Clinical characteristics, risk factors, and surgical outcomes of secondary macular hole after vitrectomy.

Secondary macular hole(MH) formation after vitrectomy is rare and its risk factors and pathogenesis are not clearly understood. This retrospective study was conducted to identify the risk factors of this complication and assess outcomes at 2 tertiary centres. The primary outcomes were the clinical characteristics associated with development of secondary MH, which included the primary diagnosis for initial vitrectomy, features on optical coherence tomography, and adjuvant surgical techniques used during the initial surgery. Secondary outcomes included the change in best-corrected visual acuity(BCVA), clinical factors associated with the need for re-operations for MH closure and prognostic factors for the visual outcomes. Thirty-eight eyes out of 6,354 cases (incidence 0.60%) developed secondary MH after undergoing vitrectomy for various vitreoretinal disorders over an 11-year period, most frequently after initial surgery for retinal detachment(RD) (9 eyes) and secondary epiretinal membrane (6 eyes). The mean age was 57.1 years (range: 17.8-76.7), and the mean follow-up was 51.1 months (range: 6.8 to 137.6). Prior to secondary MH formation, development of ERM was the most common OCT feature (19 eyes, 50%), and no cases of cystoid macular oedema (CME) were observed. A greater proportion of eyes with secondary MH had long axial lengths (32% ≥26 mm vs 5% of eyes ≤22 mm). MH closure surgery was performed in 36 eyes and closure was achieved in 34 (success rate 94%, final BCVA 20/86), with ≥3-line visual gain in 18 cases. BCVA at MH onset (OR = 0.056, P = 0.036), BCVA at post-MH surgery month 3 (OR = 52.671, P = 0.011), and axial length ≥28 mm (OR = 28.487, P = 0.030) were associated with ≥3-line visual loss; a history of macula-off RD (OR = 27.158, P = 0.025) was associated with the need for multiple surgeries for MH closure. In conclusion, secondary MH occurs rarely but most commonly after vitrectomy for RD. Patients with axial length ≥28 mm and poor BCVA at 3 months post-operation may have limited visual prognosis; those with a history of macula-off RD may require multiple surgeries for hole closure.

Impact of antibiotic resistance of pathogens and early vitrectomy on the prognosis of infectious endophthalmitis: a 10-year retrospective study.

PURPOSE: Infectious endophthalmitis (IE) is a severe complication that can lead to blindness even with treatment. However, the impact of antibiotic resistance and early vitrectomy on its prognosis has scarcely been documented. This study investigated the impact of antibiotic resistance of pathogen and early vitrectomy on the prognosis of IE. METHODS: The medical records of 171 patients treated for IE at a tertiary referral center between 2007 and 2016 were retrospectively reviewed and analyzed for etiology, pathogen, drug resistance to vancomycin or third-generation cephalosporins, treatment types and timing, and visual outcomes. Multivariate logistic regression analysis was used to determine significant prognostic factors. RESULTS: Among 171 eyes, 121 (70.8%) eyes developed IE after intraocular surgery (cataract surgery, 46.3%; intraocular injection, 13.2%), 37 (21.6%) eyes developed IE endogenously, and 9 (5.3%) eyes developed IE after trauma. The major causative pathogens were Staphylococcus aureus (9.4%) and Klebsiella pneumoniae (7.0%). In total, 72.6% of the identified pathogens demonstrated antibiotic resistance. Antibiotic resistance was associated with a worse final vision (P = .027). Visual prognosis was better for eyes treated with early vitrectomy combined with intravitreal antimicrobial injections within 24 h of onset than for eyes that received only intravitreal antimicrobial injections before undergoing delayed vitrectomy (P = .003). CONCLUSION: Antibiotic resistance of organisms causing IE is one of the most important prognostic factors. Early vitrectomy (i.e., within 24 h) may be helpful for achieving a better visual outcome. Immediate vitrectomy can be recommended, especially in IE cases caused by organisms with resistance to empirically used antibiotics.

Germ Cell Transplantation in Avian Species.

Germ cell transplantation technology has played a critical role in germline modification and preservation of genetic resources. Several germ cell transplantation systems have been developed, including sperm, oocyte, or germline stem cell transplantation systems in mammals. Meanwhile, in avian species, this has mostly relied on primordial germ cell (PGC) transplantation for efficient germline transmission. In this chapter, we describe how to isolate PGCs from avian embryos and produce germline chimeras through transplantation of donor PGCs to recipient embryos.

The transgenic chicken derived anti-CD20 monoclonal antibodies exhibits greater anti-cancer therapeutic potential with enhanced Fc effector functions.

Modern genetic techniques, enable the use of animal bioreactor systems for the production and functional enhancement of anti-cancer antibodies. Chicken is the most efficient animal bioreactor for the production of anti-cancer antibodies because of its relatively short generation time, plentiful reproductive capacity, and daily deposition in the egg white. Although several studies have focused on the production of anti-cancer antibodies in egg white, in-depth studies of the biological activity and physiological characteristics of transgenic chicken-derived anti-cancer antibodies have not been fully carried out. Here, we report the production of an anti-cancer monoclonal antibody against the CD20 protein from egg whites of transgenic hens, and validated the bio-functional activity of the protein in B-lymphoma and B-lymphoblast cells. Quantitative analysis showed that deposition of the chickenised CD20 monoclonal antibody (cCD20 mAb) from transgenic chickens increased in successive generations and with increasing transgene copy number. Ultra-performance liquid chromatography (UPLC) tandem mass spectrometry (LC/MS/MS) analysis showed that the cCD20 mAb exhibited 14 N-glycan patterns with high-mannose, afucosylation and terminal galactosylation. The cCD20 mAb did not exhibit significantly improved Fab-binding affinity, but showed markedly enhanced Fc-related functions, including complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) compared to commercial rituximab, a chimeric mAb against CD20. Our results suggest that the transgenic chicken bioreactor is an efficient system for producing anti-cancer therapeutic antibodies with enhanced Fc effector functions.

Precise gene editing of chicken Na+/H+ exchange type 1 (chNHE1) confers resistance to avian leukosis virus subgroup J (ALV-J).

Avian leukosis virus subgroup J (ALV-J), first isolated in the late 1980s, has caused economic losses to the poultry industry in many countries. As all chicken lines studied to date are susceptible to ALV infection, there is enormous interest in developing resistant chicken lines. The ALV-J receptor, chicken Na+/H+ exchange 1 (chNHE1) and the critical amino acid sequences involved in viral attachment and entry have already been characterized. However, there are no reported attempts to induce resistance to the virus by targeted genome modification of the receptor sequences. In an attempt to induce resistance to ALV-J infection, we used clustered regularly interspaced short palindromic repeats (CRISPR)-associated (CRISPR/Cas9)-based genome editing approaches to modify critical residues of the chNHE1 receptor in chicken cells. The susceptibility of the modified cell lines to ALV-J infection was examined using enhanced green fluorescent protein (EGFP)-expressing marker viruses. We showed that modifying the chNHE1 receptor by artificially generating a premature stop codon induced absolute resistance to viral infection, with mutations of the tryptophan residue at position 38 (Trp38) being very critical. Single-stranded oligodeoxynucleotide (ssODN)-mediated targeted recombination of the Trp38 region revealed that deletions involving the Trp38 residue were most effective in conferring resistance to ALV-J. Moreover, protein structure analysis of the chNHE1 receptor sequence suggested that its intrinsically disordered region undergoes local conformational changes through genetic alteration. Collectively, these results demonstrate that targeted mutations on chNHE1 alter the susceptibility to ALV-J and the technique is expected to contribute to develop disease-resistant chicken lines.