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.

Richard L. Bruno, HD, PhD

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“Non-Paralytic” Polio