Berto Tejera
Foster City
Summary
Molecular biologist (US Permanent Resident) with 3 years of postdoctoral and 3+ years of industry experience designing, executing, and optimizing molecular and cellular assays in academic and biotech settings. Proven track record in nucleic acid research, assay development, and cross-functional collaboration. Skilled in in vitro transcription (IVT), RNA transfection and mRNA-LNP testing in mammalian cell systems. Experienced in antigen expression, ELISA-based assays, and cross-functional collaboration to advance RNA-based vaccine and therapeutic programs.
Overview
13
13
years of professional experience
Work History
Scientist II - mRNA Research R&D
ReCode Therapeutics
Menlo Park, CA
04.2022 - 08.2025
- Project development experience
- Co-leaded projects to select top mRNA performers to support pre-clinical studies and clinical trials.
- Performed mRNA design and coordinated CRO manufacturing for mRNA production.
- Coordinated and performed mRNA translation efficiency experiments (cell transfection, sample preparation and capillary western).
- Coordinated and performed mRNA stability assays in LNP-mRNA treated cells (RT-qPCR).
- Selected top mRNA performers and helped to coordinate protein functional readouts.
- Presented and discussed outcomes in cross-functional meetings
- Molecular Biology
- Designed and optimized mRNA constructs for codon usage, untranslated region (UTR) selection, and poly(A) configuration to improve mRNA stability and protein yield and function enabling data-driven selection of mRNA drug candidates and accelerating development timelines.
- Developed and directed plasmid cloning workflows (Gibson Assembly, restriction digestion and site-directed mutagenesis, sequencing analysis). Participated in the clone selection to create a master cell bank.
- Performed and supervised plasmid purification (mini, midi and mega-preps) and optimized plasmid linearization to improve mRNA quality and production.
- Developed and optimized in vitro transcription (IVT) using DoE to improve mRNA yield and purity; mRNA capping (vaccinia and analogs) and mRNA purification workflows to transfer optimal conditions to CMC for mRNA large scale production.
- Designed and executed RT-qPCR assays to analyze mRNA stability in mRNA-LNP treated cells to select top mRNA performers for in vivo studies.
- Ensured documentation accuracy using ELN (Benchling), contributed to technical reports and patent applications.
- Trained and supervised junior scientists in molecular techniques and safety practices.
- Cell Biology
- Established and optimized mammalian cell transfection protocols under BSL-2 conditions to evaluate protein expression by potency assays to select top mRNA and LNP performers.
- Maintained mammalian cell cultures and prepared reagents using aseptic techniques.
- Experience in protein detection in animal tissues (lung, liver and spleen) and fluids (bronchoalveolar lavage [BALF], serum) to support translational studies (capillary Western [JESS] and [ELISA])
- Bioanalytical and Purification
- Developed, validated, and executed analytical assays for mRNA including: mRNA capping efficiency (Ribozyme test), poly(A) tail integrity (capillary electrophoresis), dsRNA content (ELISA), residual plasmid/bacteria DNA content (qPCR), RNA integrity (capillary electrophoresis), endotoxin content (chromogenic method) and protein expression (capillary Western JESS) to ensure that the mRNA passes the quality industry standards.
- Coordinated contract work organization (CRO) activities for mRNA manufacturing.
- Developed automated liquid chromatography (AKTA) FPLC purification workflows for mRNA using oligo-dT systems to increase the mRNA purity.
- Presented analytical findings to cross-functional teams to guide decision-making.
Postdoctoral Researcher - Microbiology & Immunology
University of Michigan Medical School
Ann Arbor, MI
07.2019 - 03.2022
- Investigated host-adenovirus interactions to uncover mechanisms of viral immune evasion, integrating molecular biology and cell-based models.
- Evaluated viral gene function in mammalian cells by transfection and expression assays.
- Optimized immunodetection assays (Western blot, antibody titration, immunofluorescence) for protein expression analysis.
- Supervised trainees and presented research findings at national and international conferences, contributing to collaborative scientific projects.
Associate Scientist - Human Genotyping
Codigo 46 SA de CV
Morelos, Mexico
12.2016 - 05.2019
- Performed DNA extraction from human saliva using high-throughput DNA extraction systems (Hamilton)
- Conducted DNA microarrays (Illumina HTS) for human genotyping using liquid handler (Tecan)
- Maintained experimental workflows in LIMS, ensuring quality and traceability.
- Regularly presented data in team meetings, contributing to project decisions.
Research Assistant - Molecular Virology
Autonomous University of the State of Morelos
Mexico
07.2012 - 05.2019
- Generated recombinant adenoviruses and investigated the role of the viral protein-RNA interaction and its implication on mRNA splicing and protein localization.
- Conducted RNA/DNA quantification (qPCR, RT-qPCR) and protein analysis (Western blot, immunoprecipitation, EMSA) to characterize viral late mRNA metabolism during the virus replication cycle.
- Mentored undergraduates and presented at international virology congresses.
Education
Ph.D. - Cellular and Molecular Biology
Autonomous University of the State of Morelos
Mexico01.2019
B.Sc. - Microbiology
University of Havana
Cuba01.2008
Skills
- Molecular Biology: Cloning (Gibson Assembly, restriction digestion, site-directed mutagenesis, bacterial transformation), DNA/RNA extraction, qPCR/RT-qPCR, gel and capillary electrophoresis, experience in liquid handler equipment for DNA microarrays (Tecan) and DNA extraction (Hamilton)
- RNA Technologies: In vitro transcription (IVT), mRNA capping (enzymatic and analog), poly(A) tail analysis, potency assays (capillary Western [JESS]) and electrophoretic mobility shift assay (EMSA)
- Virological Methods: Virus infections, propagation, titration (plaque assay and immunofluorescence microscopy), viral nucleic acid and protein purification and analysis
- Analytical Methods: ELISA, SDS-PAGE, endotoxin testing, nucleic acid quantification (Qubit, Nanodrop), Lipid nanoparticle (LNP) formulation testing and immunofluorescence microscopy, UV-vis, AKTA-FPLC
- Cell Culture: Human-derived cell lines, aseptic techniques, BSL-2 compliance and sample preparations
- Data & Documentation: Electronic lab notebooks (ELN), Laboratory Information Management Software (LIMS), Prism GraphPad, JMP
Timeline
Scientist II - mRNA Research R&D
ReCode Therapeutics
04.2022 - 08.2025
Postdoctoral Researcher - Microbiology & Immunology
University of Michigan Medical School
07.2019 - 03.2022
Associate Scientist - Human Genotyping
Codigo 46 SA de CV
12.2016 - 05.2019
Research Assistant - Molecular Virology
Autonomous University of the State of Morelos
07.2012 - 05.2019
B.Sc. - Microbiology
University of Havana
Ph.D. - Cellular and Molecular Biology
Autonomous University of the State of Morelos
Publications
- Tejera-Hernández, B., Goodman D., Nevarez J., Spindler K. (2022). Mouse adenovirus type 1 E4orf6 induces PKR degradation. J Virol. 96(7): e0206321. doi: 10.1128/jvi.02063-21. Epub 2022 Mar 14.
- Tejera B., López R. E., Hidalgo P. Cárdenas, R., Ballesteros, G. Rivillas, L., French, L. Amero, C., Pastor, N. Santiago, A. Groitl, P, Dobner, T. Gonzalez, R. (2019). The human adenovirus type 5 E1B 55kDa protein interacts with RNA, promoting timely DNA replication and viral late mRNA metabolism. PLoS One. 14(4): e0214882. doi: 10.1371/journal.pone.0214882.
Patents
Chen J., Tejera B., and Hennig, M (2025). Compositions and methods of treating alpha-1 antitrypsin deficiency using lipid nanoparticle compositions. United States Application No: 63/805,213 filed May 13, 2025.