Zika vaccine Current Affairs

Scientists develop world’s first plant-based Zika vaccine

Scientists from US have developed the world’s first plant-based Zika vaccine that may be more effective, safer and cheaper than other vaccines against the mosquito-borne Zika virus.

The vaccine was developed using proteins derived from Tobacco plant. Currently, there are no licensed vaccines or therapeutics available to combat Zika.

 Key Facts

The plant-based Zika vaccine works against DIII, a part of a Zika viral protein that plays a key role for the virus to infect people. All flaviviruses have the envelope protein on the outside part of the virus. It has three domains. The domain III has a unique stretch of DNA for the Zika virus.

Researchers exploited domain III to generate a robust and protective immune response that is unique for Zika. First they had grown the envelope protein in bacteria then prepared the DIII protein domain in tobacco plants. The multiple immunisation experiments of the vaccine performed on mice shows 100% protection against multiple Zika virus strains in mice.

Significance: The plant protein-based vaccine uses smallest and most unique part of the Zika virus that can still elicit a potent and robust immune response. It produces a potent protective immune response against Zika Virus and also not produce antibodies that may be cross reactive for West Nile fever, Dengue, Yellow fever or others.

About Zika virus

Zika virus is vector borne disease transmitted primarily by Aedes aegypti mosquitoes, the same mosquito that transmits dengue, West Nile fever, Yellow fever. The virus has been named after Zika forest in Uganda where it was first isolated in 1947.

The virus is capable of causing serious birth defects i.e. neurological disorders and foetal deformation known as Microcephaly in which infants are born with abnormally smaller heads. Besides a possible link between the virus and Guillain-Barré syndrome (a condition in which the body’s immune system attacks part of the nervous system) is also suspected. It is also found that, sexual transmission of Zika virus disease is possible.

The worldwide Zika threat first emerged in 2015, infecting millions in South America. The World Health Organization (WHO) had declared the disease as epidemic and global health emergency but later revoked it after the outbreak was brought under control.

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Single-dose Zika vaccine works in animals: study

 According to recent study, an innovative vaccine made from genetic material protected lab animals from the Zika virus in experiments.

A single, low dose of the vaccine shielded mice exposed to Zika five months after the shot. Even monkeys exposed five weeks after they were innoculated were also not affected by the virus.

Key Facts
  • The new vaccine is based on a modified version of genetic material called messenger RNA (mRNA). It is designed to pass under the radar of the immune system and enter directly into human cells.
  • Once there, RNA vaccine is incorporated into the cell’s protein-making machinery, it mimics the action of a live virus vaccine building up an immune response.
  • It can be delivered into the blood stream by fat-based nanoparticles. It can be injected just below the skin and is thus easy to administer.
  • RNA-based vaccines are non-replicating, i.e. they cannot integrate into the host’s genetic blueprint. It overcomes safety concern that comes with live-virus vaccines.
Background

Zika virus had erupted on a large scale in mid-2015 in which more than 1.5 million people were infected, mostly in Brazil and other countries in South America. The virus is transmitted mainly by mosquitos. It causes mild, flu-like symptoms in most people, pregnant women run the risk of giving birth to babies with severe brain damage. The World Health Organization (WHO) had declared a global health emergency in February 2016, and declared it over in November 2016.

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