Plants As an Innovative and Accelerated Vaccine-Manufacturing Solution - A plant-based expression system could provide greater speed and capacity at a comparatively low cost. - BioPharm International

ADVERTISEMENT

Plants As an Innovative and Accelerated Vaccine-Manufacturing Solution
A plant-based expression system could provide greater speed and capacity at a comparatively low cost.


BioPharm International Supplements
Volume 24, Issue 5, pp. s27-s30

THE VLP PRESENTATION SYSTEM

In the life cycle of the influenza virus, formation of the viral particle involves the budding of a portion of the host plasma membrane saturated with the viral surface proteins. HA is the major surface protein of the influenza virus with a transmembrane domain that spans through the viral envelope. The authors demonstrated that transient expression of the HA surface protein in plant cells results in the formation of VLPs budding from microdomains of the plasma membrane saturated with recombinant HA.


Figure 2: Structural characteristics of influenza virus and viruslike particles, including (a) a comparison of surface attributes, (b) a cross-section showing internal distinctions, and (c) transmission electron microscopy images of influenza viral particles and influenza viruslike particles.
At maturity, these VLPs have morphological features similar to those of the influenza virus, but only contain its immunogenic determinants, with none of the viral RNA, which is packaged within the enveloped particles of true viruses. Compared with isolated soluble antigens, antigens at the surface of VLPs have the double advantage of adopting a conformation that is identical to those found on the cognate virus, and of being presented in a multivalent structure similar to that of the native virus. These features enable VLPs to achieve enhanced stimulation of the immune response with balanced humoral and cellular components. This benefit of VLPs over soluble recombinant antigens is believed to be particularly strong in vaccine products against enveloped viruses because VLPs present the surface antigens in their natural, membrane-bound state (4). As the influenza viral particle, influenza VLPs are enveloped, pleiomorphic, and 100 to 150 nm in size (see Figure 2).

THE MANUFACTURING OF INFLUENZA VLPS

HA expression plasmid, master, and working cell bank of transformed Agrobacteria

The recombinant influenza HA gene is built in such a way that native HA is expressed, thus yielding a mature protein product identical to the wild type influenza HA protein. Expression is maximized by the integration of elements that result in high transcription of mRNA and hypertranslation of the product. In addition to these elements, a suppressor of silencing is coexpressed with the HA protein to counteract specific HA mRNA degradation (i.e., mRNA silencing) that is triggered by the significant accumulation of HA mRNA in plant cells.

Before their transfer into A. tumefaciens, the plasmids are fully sequenced to ensure sequence integrity. Upon confirmation of integrity, plasmids are introduced into A. tumefaciens, selected clones are grown in a master cell bank (MCB) that generates the working cell bank (WCB). The MCB and WCB are tested for purity and plasmid integrity.

A liquid culture of the bacterial vector is produced from the WCB and used to prepare the A. tumefaciens inoculum for infiltration.


blog comments powered by Disqus

ADVERTISEMENT

ADVERTISEMENT

New Tax Rules May Deter Future Pharma M&A
October 1, 2014
NIH Seeks to Improve Vaccine Response with New Adjuvants
September 30, 2014
New Report Details Players and Pipelines in the Biosimilar Space
September 30, 2014
Baxter International Plans to Open R&D Center for Baxalta
September 30, 2014
FDA Releases First-Ever Purple Book for Biosimilar Characterization
September 26, 2014
Author Guidelines
Source: BioPharm International Supplements,
Click here