Cloning and expression of a codon-optimized gene encoding the infl uenza A virus nucleocapsid protein in Lactobacillus casei Authors Namfon Suebwongsa Department of Microbiology and Research and Diagnostic Center for Emerging Infectious Diseases (RCEID), Faculty of Medicine, Khon Kaen University, Khon Kaen Marutpong Panya College of Medicine and Public Health, Ubon Ratchathani University, Ubon Ratchathani Wises Namwat Department of Microbiology and Research and Diagnostic Center for Emerging Infectious Diseases (RCEID), Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand. Saovaluk Sookprasert Department of Microbiology and Research and Diagnostic Center for Emerging Infectious Diseases (RCEID), Faculty of Medicine, Khon Kaen University, Khon Kaen Begoña Redruello Dairy Institute of Asturias (IPLA-CSIC), Villaviciosa Baltasar Mayo Dairy Institute of Asturias (IPLA-CSIC), Villaviciosa Miguel A. Álvarez Dairy Institute of Asturias (IPLA-CSIC), Villaviciosa Viraphong Lulitanond Department of Microbiology and Research and Diagnostic Center for Emerging Infectious Diseases Faculty of Medicine, Khon Kaen University Keywords: Lactobacillus casei, lactic acid bacteria, infl uenza A virus, viral nucleocapsid proteins, heterologous expression, codon usage Abstract Lactic acid bacteria (LAB) species are envisioned as promising vehicles for the mucosal delivery of therapeutic and prophylactic molecules, including the development of oral vaccines. In this study, we report on the expression of a synthetic nucleocapsid (NP) gene of infl uenza A virus in Lactobacillus casei. The NP gene was re-designed based on the tRNA pool and the codon usage preference of L. casei BL23. The codon-optimized NP gene was then cloned and expressed in L. casei RCEID02 under the control of a constitutive promoter, that of the lactate dehydrogenase (ldh) gene. The synthetic NP gene was further expressed in L. casei EM116 under the control of an inducible promoter, that of the structural gene of nisin (nisA) from Lactococcus lactis. Based on Western blot analysis, the specifi c protein band of NP, with a molecular mass of 56.0 kDa, was clearly detected in both expression systems. Thus, our study demonstrates the success of expressing a codon-optimized infl uenza A viral gene in L. casei. The suitability of the recombinant LAB strains for immunization purposes is currently under evaluation. [Int Microbiol 2013; 16(2):93-101]Keywords: Lactobacillus casei; lactic acid bacteria; infl uenza A virus; viral nucleocapsid proteins; heterologous expression; codon usage Downloads PDF Issue Vol. 16 No. 2 (2013) Section Research Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. The corresponding author signs for and accepts responsability for releasing this material and will act on behalf of any and all coauthors regarding the editorial review and publication process.If an article is accepted for publication in International Microbiology, the authors (or other copyright holder) must transfer to the journal the right–not exclusive–to reproduce and distribute the article including reprints, translations, photographic reproductions, microform, electronic form (offline, online) or any other reproductions of similar nature. Nevertheless, all article in International Microbiology will be available on the Internet to any reader at no cost. The journal allows users to freely download, copy, print, distribute, search, and link to the full text of any article, provided the authorship and source of the published article is cited. The copyright owner's consent does not include copying for new works, or resale. In these cases, the specific written permission of International Microbiology must first be obtained.Authors are requested to create a link to the published article on the journal's website. The link must be accompanied by the following text: "The original publication is available on LINK at <http://www.im.microbios.org>. Please use the appropiate URL for the article in LINK. Articles disseminated via LINK are indexed, abstracted, and referenced by many abstracting and information services, bibliographic networks, subscription agencies, library networks, and consortia.