A molecule in green tea, known as epigallocatechin (EGCG), blocks the entry of a Brazilian strain of Zika virus into host cells, and may hold potential benefit for prevention of Zika virus infections, a new study has found.
Bruno M. Carneiro, São Paolo State University, Brazil, and colleagues published the results of their study in the journal Virology.
“The mechanism by which this inhibition occurs is probably related to the direct interaction of the drug with lipid envelope, leading to a subsequent destruction of the virus particle,” the authors write.
Zika virus, which causes Zika virus disease, is an emerging mosquito-borne virus that is transmitted to people predominantly through the bite of an Aedes mosquito. The disease originated in 1947 in Uganda, and was mostly confined to monkeys for several decades. However, in 2007, a disease outbreak on Micronesia’s Yap Island turned out to be caused by Zika virus. Later outbreaks of Zika disease virus also occurred in French Polynesia and Easter Island, and, most recently, outbreaks were confirmed in Brazil and Colombia.
Of increasing concern, the Zika virus disease outbreak in Brazil has been linked to birth defects, in particular microcephaly. However, no vaccine or approved drug is available for the treatment or prevention of Zika virus infection. With this in mind, Carneiro and colleagues conducted a study to examine the effect of EGCG on entry of Zika virus into cells.
EGCG is a polyphenol that is found in large quantities in green tea, and has been shown to have activity against many viruses, including HIV, by preventing viral entry into host cells. The researchers used a Brazilian strain of Zika virus to infect cells in a cell culture system in the laboratory. They mixed the virus with different concentrations of EGCG and added the different mixtures to the cells.
They found that higher concentrations of EGCG (100 μM or greater), in particular, prevented entry of more than 90% of the Zika virus into the cells.
According to the authors, this is the first study to show the potential benefit of EGCG in protecting against Zika virus infection. They also note that EGCG has been shown to be safe when given to healthy individuals, and that studies in rats have also suggested that EGCG may even be safe for administration to pregnant women.
Nevertheless, the authors conclude that further studies to assess the bioavailability and safety of EGCG, especially in pregnant women, should be performed before its clinical use can be considered.
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Carneiro BM, Batista MN, Braga AC, Nogueira ML, Rahal P. The green tea
molecule EGCG inhibits Zika virus entry. Virology. 2016 Jun 23;496:215-218.
During ZIKV the outbreak in Brazil it was observed an increase of almost 20 times the number of reported cases of microcephaly in newborn babies. There is no vaccine or approved drug available for the treatment and prevention of infections by this virus. EGCG, a polyphenol present in green tea has been shown to have an antiviral activity for many viruses. In view of the need for the development of a drug against a Brazilian strain of ZIKV, we assessed the effect of EGCG on ZIKV entry in Vero E6 cells. The drug was capable of inhibiting the virus entry by at least 1-log (>90%) at higher concentrations (>100μM). The pre-treatment of cells with EGCG did not show any effect on virus attachment. This is the first study to demonstrate the effect of EGCG on ZIKV indicating that this drug might be possibility to be used for prevention of Zika virus infections.