Plant Based Polio Vaccines
From Dr. Bruno: I found this article fascinating.
Plant-Made Poliovirus Vaccines – Safe alternatives for global vaccination
By: Omayra C. Bolaños-Martínez and Richard Strasser*
Department of Applied Genetics and Cell Biology, Institute of Plant Biotechnology and Cell Biology, University of Natural
Resources and Life Sciences, Vienna, Austria. October, 2022
“Human polioviruses are highly infectious viruses that are spread mainly through the fecal-oral route.
Infection of the central nervous system frequently results in irreversible paralysis, a disease called
poliomyelitis. Children under five years are mainly affected if they have not acquired immunity
through natural infection or via vaccination. Current polio vaccines comprise the injectable
inactivated polio vaccine (IPV, also called the Salk vaccine) and the live-attenuated oral polio
vaccine (OPV, also called the Sabin vaccine). The main limitations of the IPV are the reduced
protection at the intestinal mucosa, the site of virus replication, and the high costs for manufacturing
due to use of live viruses. While the OPV is more effective and stimulates mucosal immunity, it is
manufactured using live-attenuated strains that can revert into pathogenic viruses resulting in major
safety concerns and vaccine-derived outbreaks. During the last fifteen years, plant-based poliovirus
vaccines have been explored by several groups as a safe and low-cost alternative, and promising
results in protection against challenges with viruses and induction of neutralizing antibodies have
been obtained. However, low yields and a high frequency in dose administration highlight the need
for improvements in polioviral antigen production. In this review, we provide insights into recent
efforts to develop plant-made poliovirus candidates, with an emphasis on strategies to optimize the
production of viral antigens. . . . ”
Introduction
“Poliomyelitis (polio) is a viral disease which is caused by polioviruses that are transmitted by the
fecal-oral route and predominantly affects children under five years. The severity ranges from
asymptomatic occurrence to meningitis and acute flaccid paralysis. Polio has the peculiarity to
seriously affect the central nervous system (CNS) and damage the motor neurons located in the
anterior horn of spinal nerve roots. This harm leads to muscular dysfunction or even death when
vital body functions such as deglutition or respiration are compromised (Sabin, 1956). Post-polio
syndrome (PPS) is a non-contagious and slowly progressive appearance of a variety of symptoms
that occur many years or decades after virus infection and involves symptoms like muscular
weakness, limb paresis with muscle atrophy, paresthesia, joints pain, fatigue, physical and mental
activity deterioration. The cause of PPS remains poorly understood, it may be related to the slow
degeneration of individual nerve terminals in the motor units (Pastuszak et al., 2017).
Polio has a huge impact on developing countries with poor sanitation and weak public health
systems. Due to worldwide vaccination efforts that began in the late ‘80s with the creation of the
Global Polio Eradication Initiative (GPEI), polio has been considered almost completely eradicated.
To date, polio remains endemic in two countries: Afghanistan and Pakistan (Greene et al., 2019).
However, recent cases of paralytic poliomyelitis in the US, the UK and Israel highlight that poliovirus
is still a worldwide threat that needs attention in all countries (Hill et al., 2022). These new cases in
countries deemed polio-free were reported in under vaccinated communities which emphasizes the
need to improve vaccination coverage for global polio eradication. . . . ”
Future directions
“To achieve global poliomyelitis eradication, innovative vaccines are needed since the actual
vaccines are produced with infectious or attenuated poliovirus strains that raise safety concerns.
Endemic and vaccine-derived polio cases are mainly observed in developing or low-income countries
which urges the need to develop affordable and accessible vaccines. Transient expression in plants
provides a fast and flexible approach to produce vaccines in case of newly emerging viral pathogens
as shown by the current COVID-19 pandemic or in cases where a vaccine has to be adapted quickly
to a mutating virus. For genetically more stable viruses, transgenic expression could be cheaper and
provide a constant supply for vaccination. . . . .”
Article abbreviated from the original. The full article.