Seaweed compound blocks cervical cancer virus
* 13:14 14 July 2006
* NewScientist.com news service
* Roxanne Khamsi
A seaweed extract called carrageenan strongly inhibits human papillomavirus – known to cause cervical cancer – from entering human cells in the lab, a new study shows. The compound, derived from red algae, is already used as a thickening agent in infant feeding formulas and in sexual lubricants. The researchers hope their findings could one day help prevent the spread of the virus.
Human papillomavirus is sexually transmitted and certain high-risk strains are linked to cervical cancer. Condoms can prevent its spread to a certain degree. And a new vaccine called Gardasil – recently been recommended for girls aged 11 to 12 by an influential US advisory panel – is almost 100% effective in protecting against the most dangerous HPV strains. However, the three-dose vaccination course costs $360, which puts many women off. And this is especially expensive for women in developing countries.
Developing an inexpensive gel, or microbicide, to block HPV might help stop its spread, says the John Schiller at the National Cancer Institute in Maryland, US.
His team tested various compounds in the lab, screening for the ones that interfered most with the virus’ ability to invade human cells. The researchers found that carrageenan strongly inhibited different HPV strains’ ability to attach and therefore enter human cells. “We were floored by how much better it worked than anything else we have tested,” says Schiller.
Serendipity
The researchers note that although lab tests have shown some strains of HIV and herpes as vulnerable to carrageenan, genital HPV appears about a thousand-fold more susceptible to the compound. Their tests also showed that carrageenan was effective against HPV strains 16 and 18 – two of the most dangerous in terms of cervical cancer risk.
Carrageenan is already used a thickening agent in foods such as baby formula, and is perfectly safe to ingest. The researchers note it is serendipitous that some sexual lubricants already contain the compound. But these are not yet proven to be effective in preventing the spread of HPV, stresses team member Cynthia Thompson.
She says pharmaceutical companies will have to pursue this idea with future tests and then apply for approval from drug regulators to market their products as HPV blockers.
Roughly 50% of sexually active women between the ages of 18 and 22 are infected with human papillomavirus (HPV) at some point, although their own immune systems can clear infections caused by the less aggressive strains.
Journal reference: PLoS Pathogens (DOI: 10.1371/journal.ppat.0020069)
Carrageenan Blocks Human Pappiloma Virus! W00t!
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