Griffithsin is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

isolated from the

red algae Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

Griffithsia ''Griffithsia'' is a genus of red algae in the family Wrangeliaceae. Carl Adolph Agardh named ''Griffithsia'' in the honour of phycologist Amelia Griffiths (1768–1858). Griffithsin is a protein isolated from species of ''Griffithsia''. Spe ...

''. It has a 121- amino acid sequence which exhibits a Jacalin-like lectin fold. Several structures of this protein have been solved by

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

and deposited in the PDB. It has been shown

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

to be a highly potent

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

entry inhibitor Entry inhibitors, also known as fusion inhibitors, are a class of antiviral drugs that prevent a virus from entering a cell, for example, by blocking a receptor. Entry inhibitors are used to treat conditions such as HIV and hepatitis D. HIV entr ...

. It is currently being investigated as a potential

microbicide An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

for use in the prevention of the transmission of

. Griffithsin shows a broad spectrum ability to bind to the glycoproteins of other viruses, such as the

coronavirus Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the com ...

. Griffithsin's three identical carbohydrate binding sites bind to oligosaccharides present on some envelopes of viral glycoproteins. This was demonstrated by

and

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...

studies. For instance, it was shown that griffithsin binds to the SARS-CoV spike glycoprotein to inhibit entry of the SARS virus and thus inhibit infection. A 2014 study showed griffithsin to also possess useful antiviral activity against

Ebolavirus The genus ''Ebolavirus'' (- or ; - or ) is a virological taxon included in the family ''Filoviridae'' (filament-shaped viruses), order ''Mononegavirales''. The members of this genus are called ebolaviruses, and encode their genome in the form ...

. As reported in March 2009, Kenneth Palmer and coworkers modified the tobacco mosaic virus to incorporate the griffithsin gene and infected more than 9,300

tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

plants. They were able to extract enough griffithsin to produce about 100,000 HIV microbicide doses from the leaves.

References

{{HIVpharm Eukaryote proteins Entry inhibitors