This document discusses vaccines and the potential for using plants as bioreactors to produce vaccines. It notes that vaccines provide active immunity against diseases and typically contain weakened or killed forms of pathogens. Vaccination is an effective public health measure. Recently, genetically engineering plants to express antigen proteins from pathogens has emerged as a way to develop subunit vaccines more economically than traditional methods. The document outlines opportunities like safety, immune response, stability, low cost, and challenges like regulatory concerns for plant-based vaccines. It provides examples of plant-made influenza vaccines in development that could allow rapid production in response to pandemics.

1. BUSHRA JAMIL

2. VACCINE
 A vaccine is a biological preparation that provides
active acquired immunity to a particular disease.
 A vaccine typically contains an agent that resembles a
disease-causing microorganism and is often made
from weakened or killed forms of the microbe, its
toxins or one of its surface proteins.

3.  Vaccination is important and effective public-health
measure for safeguarding against disturbing outcomes
of infectious diseases.
 Current vaccines rely on the use of either attenuated
(weakened) or killed strains of pathogens, e.g. against
diphtheria, tetanus, measles and mumps.
 For some vaccines, such as the one against human
smallpox, a strain from a different species (cowpox) is
used instead.

4.  In the last several years, a novel approach for
developing subunit vaccines has emerged as a result of
the genetic engineering technology: the use of plants
as hosts—biological bioreactors.
 the most economical and technically reasonable class
of products using this approach involves the genetic
engineering of genes to express novel proteins

5. Opportunities
 The important features is that the effective vaccine
include safety, protective immunity that is sustained
for long periods of time , stability, ease of
administration, low cost and few side-effects.
 Plants that have been engineered with genes encoding
antigenic proteins of various pathogenic viral and
bacterial organisms have been to correctly express the
proteins that bring out production of antibodies in
mammalian hosts.

6.  Plants can readily and properly handle the
downstream processing of foreign proteins, including
expression, folding, assembly, and glycosylation, all
contributing to the fidelity of antigenic proteins
 these proteins maintain their activity and efficacy, thus
contributing to their viability as subunit-vaccine
candidates
 Plants can produce not only single, simple foreign
proteins, but also complex multimeres, such as
secretory proteins and antibodies

7.  They cost less to produce than via fermentation or
bioreactors; plants can be grown in the field or in a
greenhouse relatively inexpensively.
 When produced in edible parts of the plant, such as
grain, fruit or even leaves, subunit vaccines may not
require purification.

8.  The advantages and opportunities from producing
subunit vaccines in plants may be summarized as
follows:
 Elimination of risk of contamination with infectious
agents
 With oral delivery, they activate the mucosal immune
system—the first line of defense
 Avoidance of injections
 – reduced risk of transmission of other infectious
agents through contaminated needles

9.  – reduced risk of transmission of other infectious
agents through contaminated needle
 Longer shelf-life
 Cost-effective in large quantities

10. Challenges
 The challenges in front of plant-based-vaccine
development include technical, regulatory and
economic aspects and public awareness.
 a plant system that can be grown under conditions
that minimize environmental risks, such as transfer of
pollen from transgenic to conventional varieties .
 Expression of antigens in plants is a major regulatory
concern.

11.  Targeting expression via a tissue-specific promoter
driving the transgene may reduce regulatory
concerns.
 Depending on the target protein product, levels of 10
mg/kg of plant dry weight of a crop may be sufficient,
although levels of 100 mg/kg or higher are more likely
to be necessary
 Approximately 50 kg per year of a particular antigenic
protein would certainly meet economic possibility.

12.  The use of food crops for production of plant-based
vaccines have been accompanied with calls for
targeting non-food crops for pharmaceutical purposes,
whether for the production of beneficial proteins or
plant-based vaccines.

13. Successful cases of plant made
bio-pharmaceutical
 INFLUENZA VACCINE:
 One of the most advance plant-based human vaccine
is under development by medicago Inc(USA and
Canada)
 Candidate influenza vaccine have been developed by
means of expressing the hemagglutinin(HA) protein
of H5N1 INFLUENZA and H1N1 viruses, so as to
obtain VLPs in a trainsent expression system in
Nicotinana bentamiana plants.

14.  This platform is proposed as an ideal approach for
producing vaccine quickly , which is critical for new
pandemic influenza strains and viruses such as
SARS-CoV .
 It is estimated that plant –based vaccines produced
in a transient expression system can be generated
with in 3 weeks from the release of sequence
information