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Elias M, Guan X, Hudson D, Bose R, Kwak J, Petrounia I, Touah K, Mansour S, Yue P, Errasti G, Delacroix T, Ghosh A, Chakrabarti R. Evolution of Organic Solvent-Resistant DNA Polymerases. ACS Synth Biol 2023; 12:3170-3188. [PMID: 37611245 DOI: 10.1021/acssynbio.2c00515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
The introduction of thermostable polymerases revolutionized the polymerase chain reaction (PCR) and biotechnology. However, many GC-rich genes cannot be PCR-amplified with high efficiency in water, irrespective of temperature. Although polar organic cosolvents can enhance nucleic acid polymerization and amplification by destabilizing duplex DNA and secondary structures, nature has not selected for the evolution of solvent-tolerant polymerase enzymes. Here, we used ultrahigh-throughput droplet-based selection and deep sequencing along with computational free-energy and binding affinity calculations to evolve Taq polymerase to generate enzymes that are both stable and highly active in the presence of organic cosolvents, resulting in up to 10% solvent resistance and over 100-fold increase in stability at 97.5 °C in the presence of 1,4-butanediol, as well as tolerance to up to 10 times higher concentrations of the potent cosolvents sulfolane and 2-pyrrolidone. Using these polymerases, we successfully amplified a broad spectrum of GC-rich templates containing regions with over 90% GC content, including templates recalcitrant to amplification with existing polymerases, even in the presence of cosolvents. We also demonstrated dramatically reduced GC bias in the amplification of genes with widely varying GC content in quantitative polymerase chain reaction (qPCR). By expanding the scope of solvent systems compatible with nucleic acid polymerization, these organic solvent-resistant polymerases enable a dramatic reduction of sequence bias not achievable through thermal resistance alone, with significant implications for a wide range of applications including sequencing and synthetic biology in mixed aqueous-organic media.
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Affiliation(s)
- Mohammed Elias
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Xiangying Guan
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Devin Hudson
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Rahul Bose
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Joon Kwak
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Ioanna Petrounia
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Kenza Touah
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Sourour Mansour
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Peng Yue
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Gauthier Errasti
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Thomas Delacroix
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Anisha Ghosh
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
- McGill University, 845 Rue Sherbrooke Ouest, Montreal, QC H3A 0G4, Canada
| | - Raj Chakrabarti
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
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PCR enhancers: Types, mechanisms, and applications in long-range PCR. Biochimie 2022; 197:130-143. [DOI: 10.1016/j.biochi.2022.02.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 02/06/2022] [Accepted: 02/24/2022] [Indexed: 12/21/2022]
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Xu L, Qi J, Wen Y, Liang W, Wang L, Yang Z, Yang X, Qi Y, Duan M, Zhao K, Gu J, Shen Y, Rao P, Ding M, Ren S, Li L, Liu G. A polyA DNA probe-based ultra-sensitive and structure-distinguishable electrochemical biosensor for the analysis of RNAi transgenic maize. Analyst 2021; 146:3526-3533. [PMID: 33881427 DOI: 10.1039/d1an00313e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Since the application of RNA interference (RNAi) is rapidly developing in GMO technology, accurate and sensitive detection of functional RNA molecules was urgently needed, for the safety and functional assessment of RNAi crops. In this work, we developed an electrochemical biosensor for transgene-derived long RNA based on a poly-adenine (polyA) DNA capture probe. The polyA self-assembling monolayer (SAM) provided enhanced interface stability and optimized surface density for the subsequent hybridization of the long RNA molecule. A multiple reporter probe system (MRP) containing 12 reporter probes (RPs) and 2 spacers was applied to open the complex molecular secondary structure and hybridize with the long RNA, with the critical assistance of dimethyl sulfoxide (DMSO). By using 3 addressable RPs, structural recognition was performed among long stem-loop RNA, long dsRNA (no loop), and siRNA. Excellent selectivity was achieved when the extracted total RNA samples were directly analyzed. When reverse transcription recombinase polymerase amplification (RT-RPA) technology was combined, the sensitivity was improved to 10 aM. To the best of our knowledge, this is the first electrochemical biosensor with the excellent capability of quantification and structural analysis of the long RNA of the RNAi GMO. Our work shows great potential in a wide range of RNAi GMO samples.
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Affiliation(s)
- Li Xu
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Jiawei Qi
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China. and College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai, 201620, P.R. China
| | - Yanli Wen
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Wen Liang
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Lele Wang
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Zhenzhou Yang
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Xue Yang
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Yu Qi
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Manlei Duan
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Keke Zhao
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Jie Gu
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Yiji Shen
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Pinhua Rao
- College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai, 201620, P.R. China
| | - Min Ding
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Shuzhen Ren
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
| | - Liang Li
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Gang Liu
- Laboratory of Biometrology, Division of Chemistry and Ionizing Radiation Measurement Technology, Shanghai Institute of Measurement and testing technology, Shanghai, 201203, P.R. China.
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Disruptors, a new class of oligonucleotide reagents, significantly improved PCR performance on templates containing stable intramolecular secondary structures. Anal Biochem 2021; 624:114169. [PMID: 33766577 DOI: 10.1016/j.ab.2021.114169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 11/21/2022]
Abstract
Intramolecular secondary structures within templates have been shown to lower PCR performance. Whereas many approaches have been developed to mitigate such impairment on PCR, their effects can vary greatly depending on template sequences. Here we present a novel, universally effective approach to improve PCR performance involving specifically designed oligonucleotides called disruptors. A disruptor contained three functional components, an anchor designed to initiate template binding, an effector to disrupt intramolecular secondary structure, and a 3' blocker to prevent its elongation by DNA polymerase. A functional mechanism for a disruptor to improve PCR efficiency was proposed where anchor first binds to template followed by effector-mediated strand displacement to unwind intramolecular secondary structure. Such a mechanism was consistent with the observation that anchor played a more critical role for disruptor function. As an example of potential disruptor applications, inverted terminal repeat sequences of recombinant adeno-associated virus vectors were successfully amplified in the presence of disruptors despite their well-known reputation as some of the most difficult templates for PCR amplification and Sanger sequencing due to their ultra-stable T-shaped hairpin structures. In stark contrast, both DMSO and betaine, two PCR additives routinely used to facilitate PCR amplification and Sanger sequencing of GC-rich templates, did not demonstrate any improving effect.
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Swenson SJ, Gemeinholzer B. Testing the effect of pollen exine rupture on metabarcoding with Illumina sequencing. PLoS One 2021; 16:e0245611. [PMID: 33529182 PMCID: PMC7853484 DOI: 10.1371/journal.pone.0245611] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 01/04/2021] [Indexed: 12/21/2022] Open
Abstract
Pollen metabarcoding has received much attention recently for its potential to increase taxonomic resolution of the identifications of pollen grains necessary for various public health, ecological and environmental inquiry. However, methodologies implemented are widely varied across studies confounding comparisons and casting uncertainty on the reliability of results. In this study, we investigated part of the methodology, the effects of level of exine rupture and lysis incubation time, on the performance of DNA extraction and Illumina sequencing. We examined 15 species of plants from 12 families with pollen that varies in size, shape, and aperture number to evaluate effort necessary for exine rupture. Then created mock communities of 14 of the species from DNA extractions at 4 levels of exine rupture (0, 33, 67, and 100%) and two levels of increased lysis incubation time without exine rupture (2 or 24 hours). Quantities of these DNA extractions displayed a positive correlation between increased rupture and DNA yield, however increasing time of lysis incubation was associated with decreased DNA yield. Illumina sequencing was performed with these artificial community treatments with three common plant DNA barcode regions (rbcL, ITS1, ITS2) with two different primer pairings for ITS2 and rbcL. We found decreased performance in treatments with 0% or 100% exine rupture compared to 33% and 67% rupture, based on deviation from expected proportions and species retrieval, and increased lysis incubation was found to be detrimental to results.
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Yang Z, Le JT, Hutter D, Bradley KM, Overton BR, McLendon C, Benner SA. Eliminating primer dimers and improving SNP detection using self-avoiding molecular recognition systems. Biol Methods Protoc 2020; 5:bpaa004. [PMID: 32395633 PMCID: PMC7200914 DOI: 10.1093/biomethods/bpaa004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 01/25/2023] Open
Abstract
Despite its widespread value to molecular biology, the polymerase chain reaction (PCR) encounters modes that unproductively consume PCR resources and prevent clean signals, especially when high sensitivity, high SNP discrimination, and high multiplexing are sought. Here, we show how "self-avoiding molecular recognition systems" (SAMRS) manage such difficulties. SAMRS nucleobases pair with complementary nucleotides with strengths comparable to the A:T pair, but do not pair with other SAMRS nucleobases. This should allow primers holding SAMRS components to avoid primer-primer interactions, preventing primer dimers, allowing more sensitive SNP detection, and supporting higher levels of multiplex PCR. The experiments here examine the PCR performances of primers containing different numbers of SAMRS components placed strategically at different positions, and put these performances in the context of estimates of SAMRS:standard pairing strengths. The impact of these variables on primer dimer formation, the overall efficiency and sensitivity of SAMRS-based PCR, and the value of SAMRS primers when detecting single nucleotide polymorphisms (SNPs) are also evaluated. With appropriately chosen polymerases, SNP discrimination can be greater than the conventional allele-specific PCR, with the further benefit of avoiding primer dimer artifacts. General rules guiding the design of SAMRS-modified primers are offered to support medical research and clinical diagnostics products.
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Affiliation(s)
- Zunyi Yang
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 7, Alachua, FL 32615, USA
- Firebird Biomolecular Sciences LLC, 13709 Progress Blvd, Box 17, Alachua, FL 32615, USA
| | - Jennifer T Le
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 7, Alachua, FL 32615, USA
| | - Daniel Hutter
- Firebird Biomolecular Sciences LLC, 13709 Progress Blvd, Box 17, Alachua, FL 32615, USA
| | - Kevin M Bradley
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 7, Alachua, FL 32615, USA
- Firebird Biomolecular Sciences LLC, 13709 Progress Blvd, Box 17, Alachua, FL 32615, USA
| | - Benjamin R Overton
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 7, Alachua, FL 32615, USA
| | - Chris McLendon
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 7, Alachua, FL 32615, USA
- Firebird Biomolecular Sciences LLC, 13709 Progress Blvd, Box 17, Alachua, FL 32615, USA
| | - Steven A Benner
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Blvd, Box 7, Alachua, FL 32615, USA
- Firebird Biomolecular Sciences LLC, 13709 Progress Blvd, Box 17, Alachua, FL 32615, USA
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Jakubovska J, Tauraite D, Birštonas L, Meškys R. N4-acyl-2'-deoxycytidine-5'-triphosphates for the enzymatic synthesis of modified DNA. Nucleic Acids Res 2019; 46:5911-5923. [PMID: 29846697 PMCID: PMC6158702 DOI: 10.1093/nar/gky435] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/08/2018] [Indexed: 02/06/2023] Open
Abstract
A huge diversity of modified nucleobases is used as a tool for studying DNA and RNA. Due to practical reasons, the most suitable positions for modifications are C5 of pyrimidines and C7 of purines. Unfortunately, by using these two positions only, one cannot expand a repertoire of modified nucleotides to a maximum. Here, we demonstrate the synthesis and enzymatic incorporation of novel N4-acylated 2′-deoxycytidine nucleotides (dCAcyl). We find that a variety of family A and B DNA polymerases efficiently use dCAcylTPs as substrates. In addition to the formation of complementary CAcyl•G pair, a strong base-pairing between N4-acyl-cytosine and adenine takes place when Taq, Klenow fragment (exo–), Bsm and KOD XL DNA polymerases are used for the primer extension reactions. In contrast, a proofreading phi29 DNA polymerase successfully utilizes dCAcylTPs but is prone to form CAcyl•A base pair under the same conditions. Moreover, we show that terminal deoxynucleotidyl transferase is able to incorporate as many as several hundred N4-acylated-deoxycytidine nucleotides. These data reveal novel N4-acylated deoxycytidine nucleotides as beneficial substrates for the enzymatic synthesis of modified DNA, which can be further applied for specific labelling of DNA fragments, selection of aptamers or photoimmobilization.
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Affiliation(s)
- Jevgenija Jakubovska
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Daiva Tauraite
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Lukas Birštonas
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
| | - Rolandas Meškys
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania
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Pavón-Romero GF, Pérez-Rubio G, Ramírez-Jiménez F, Ambrocio-Ortiz E, Bañuelos-Ortiz E, Alvarado-Franco N, Xochipa-Ruiz KE, Hernández-Juárez E, Flores-García BA, Camarena ÁE, Terán LM, Falfán-Valencia R. MS4A2-rs573790 Is Associated With Aspirin-Exacerbated Respiratory Disease: Replicative Study Using a Candidate Gene Strategy. Front Genet 2018; 9:363. [PMID: 30254660 PMCID: PMC6141666 DOI: 10.3389/fgene.2018.00363] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/21/2018] [Indexed: 01/08/2023] Open
Abstract
Aspirin exacerbated respiratory disease (AERD) is a set of diseases of the unified airway, and its physiopathology is related to disruption of the metabolism of arachidonic acid (AA). Genetic association studies in AERD had explored single nucleotide polymorphism (SNPs) in several genes related to many mechanisms (AA metabolism, inflammation, drug metabolism, etc.) but most lack validation stages in second populations. Our aim is to evaluated whether contribution to susceptibility of SNPs reported in other populations are associated with AERD in Mexican Mestizo patients. We developed a replicative study in two stages. In the first, 381 SNPs selected by fine mapping of associated genes, (previously reported in the literature), were integrated into a microarray and tested in three groups (AERD, asthma and healthy controls -HC-) using the GoldenGate array. Results associated to risk based on genetic models [comparing: AERD vs. HC (comparison 1, C1), AERD vs. asthma (C2), and asthma vs. HC (C3)] were validated in the second stage in other population groups using qPCR. In the first stage, we identified 11 SNPs associated with risk in C1.The top SNPs were ACE-rs4309C (p = 0.0001) and MS4A2-rs573790C (p = 0.0002). In C2, we detected 14 SNPs, including ACE-rs4309C (p = 0.0001). In C3, we found MS4A2-rs573790C (p = 0.001). Using genetic models, C1 MS4A2-rs57370 CC (p = 0.001), and ACE-rs4309 CC (p = 0.002) had associations. In C2 ACE-rs4309 CC (p = 0.0001) and C3 MS4A2-rs573790 CC (p = 0.001) were also associate with risk. In the second stage, only MS4A2-rs573790 CC had significance in C1 and C3 (p = 0.008 and p = 0.03). We concluded that rs573790 in the MS4A2 gene is the only SNP that supports an association with AERD in Mexican Mestizo patients in both stages of the study.
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Affiliation(s)
- Gandhi F Pavón-Romero
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Gloria Pérez-Rubio
- HLA Laboratory, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Fernando Ramírez-Jiménez
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Enrique Ambrocio-Ortiz
- HLA Laboratory, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Elisé Bañuelos-Ortiz
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Norma Alvarado-Franco
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Karen E Xochipa-Ruiz
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Elizabeth Hernández-Juárez
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Beatriz A Flores-García
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Ángel E Camarena
- HLA Laboratory, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
| | - Luis M Terán
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico.,Biomedicine in the Post-Genomic Era, Mexico City, Mexico
| | - Ramcés Falfán-Valencia
- HLA Laboratory, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
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