Expression of a functional single-chain antibody via Corynebacterium pseudodiphtheriticum

High-level secretory production of recombinant single-chain variable fragment (scFv) in Corynebacterium glutamicum

We describe the development of a new secretory production system for the enhanced production of a single-chain variable fragment (scFv) against the anthrax toxin in Corynebacterium glutamicum. For efficient secretory production of the antibody fragment, the following components were examined: (1) signal peptides, (2) codon usage of antibody fragment, (3) promoters, (4) 5' untranslated region (5' UTR) sequence, and (5) transcriptional terminator. Among all the systems examined, the use of a codon-optimized gene sequence, a Sec-dependent PorB signal peptide, and a fully synthetic H36 promoter, allowed the highest production of antibody fragments in a culture medium. For large-scale production, fed-batch cultivations were also conducted in a 5-L lab-scale bioreactor. When cells were cultivated in semi-defined media, cells could grow up to an OD600 of 179 for 32 h and an antibody fragment concentration as high as 68 mg/L could be obtained in a culture medium with high purity. From the culture medium, the secreted antibody was successfully purified using a simple purification procedure, with correct binding activity confirmed by enzyme-linked immunosorbent assay. To the best of our knowledge, this is the first report of a fed-batch cultivation for antibody fragment production in C. glutamicum.

Microbiome influences on insect host vector competence

Insect symbioses lack the complexity and diversity of those associated with higher eukaryotic hosts. Symbiotic microbiomes are beneficial to their insect hosts in many ways, including dietary supplementation, tolerance to environmental perturbations and maintenance and/or enhancement of host immune system homeostasis. Recent studies have also highlighted the importance of the microbiome in the context of host pathogen transmission processes. Here we provide an overview of the relationship between insect disease vectors, such as tsetse flies and mosquitoes, and their associated microbiome. Several mechanisms are discussed through which symbiotic microbes can influence the ability of their host to transmit pathogens, as well as potential disease control strategies that harness symbiotic microbes to reduce pathogen transmission through an insect vector.

Development of paratransgenic Artemia as a platform for control of infectious diseases in shrimp mariculture

AIM

To study the accumulation and retention of recombinant proteins in Artemia gut for optimizing paratransgenic disease control in shrimp aquaculture.

METHODS AND RESULTS

Transgenic Escherichia coli expressing fluorescent marker proteins and the transgenic cyanobacterium Synechococcus bacillarus expressing a functional murine single chain antibody, DB3, were fed to Artemia franciscana. Stable expression and retention of several marker molecules (e.g. GFP, DS Red and DB3) up to 10 h after of feeding with E. coli were evident within the gut of Artemia. Engineered strains of S. bacillarus expressing DB3 accumulated within the gut of Artemia with detectable antibody activity for 8-10 h of feeding via ELISA, coincident with the time period of the highest density of transgenic S. bacillarus in the Artemia gut.

CONCLUSIONS

Artemia fed transgenic bacteria or algae accumulated recombinant proteins for up to 10 h that retained biological activity. Co-delivery of multiple recombinant proteins simultaneously in the gut of Artemia was also demonstrated.

SIGNIFICANCE AND IMPACT OF THE STUDY

Expression of molecules that target infectious agents of mariculture in shrimp via commonly deployed feed organisms such as Artemia could potentially offer powerful new tools in the ongoing global effort to increase food supply.