Thursday, July 14, 2016

Zika virus and green tea

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.


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.


  1. On the heels of new data suggesting the Zika epidemic will last for another 3 years, a new case reveals there may be an additional mode of sexual transmission of the virus.

    The Centers for Disease Control and Prevention (CDC) recently reported that males may now be susceptible to sexual transmission of the Zika virus through intercourse with females. Previously, the CDC reported that the Zika virus can be transferred in semen excreted during vaginal, oral, and anal sex. However, a recent case reported in New York City is the first to indicate that a female may also be able to pass on the virus to a male through bodily fluids excreted during sexual intercourse.

    Infection with the Zika virus is known to be most harmful in pregnant women. There has been consensus that Zika infection may cause microcephaly in infected fetuses. Further analysis of the congenital effects of Zika have also proved that the virus may cause neurological impairments that may not be detectable through microcephaly testing.

    - See more at:

  2. Which came first: high Zika viral load or a diminished immune system? This is a question that epidemiologists and medical experts from the Centers for Disease Control and Prevention are pondering in regards to the recent case of Zika identified in Salt Lake City, Utah that may have resulted in the individual's death.

    Just last week a Utah resident was reported to have died with a Zika infection in June. The CDC confirmed that the male patient presented with a “unique situation”: an unusually elevated Zika blood viral load (100,000 times higher than any other sampled Zika patients). In what CDC experts called a “chicken or egg” investigation, it was noted that it is still unclear whether the elderly patient died from the Zika infection or from other underlying comorbidities. Thus, the CDC is conducting a “thorough review” to understand the clinical course of the deceased patient’s underlying comorbidities to uncover whether the high viral load contributed to the patient’s death, or if the patient’s comorbidities left him immunocompromised, which lead to the high viral load.

    Now, a family member of the deceased patient has tested positive for the Zika virus. The individual experienced mild symptoms associated with a Zika infection, and a rapid recovery, as is the “typical clinical course” of the virus. At the moment there is no clear evidence as to how the patient became infected.

    Although the primary mode of transmission of the Zika virus remains the bite of an infected female Aedes aegypti mosquito, the virus has also been identified in contaminated saliva, blood, semen, and urine.

    The CDC has dispatched an Emergency Response Team (CERT), including infection control, virology, mosquito control, disease investigation and health communications experts, to work in conjunction with the Utah Department of Health to help investigate this “unusual” case of Zika transmission. CERT will be conducting interviews with other family members of the deceased patient as well as healthcare workers who may have come in contact with him. In addition, although Utah does not harbor any of the Zika mosquito vectors (Ae. aegypti and Aedes albopictus), the team will be collecting local mosquitos for viral testing.

    During a briefing, CDC experts confirmed that nothing can be truly ruled out in terms of modes of viral transmission. However, they believe that two scenarios are “extremely unlikely”: Zika is an airborne virus; other mosquito populations within this particular area have become Zika vectors. It was confirmed that, thus far, there has been no clinical evidence of Zika transmission through casual contact, sneezing, or coughing. Nonetheless, Michael Bell, MD, deputy director of the Division of Healthcare Quality Promotion, confirmed that the CDC is currently meticulously assessing the situation to see if any other mode of transmission is possible. Although the recently identified patient is a family member of the deceased, it is not impossible that this patient could have acquired a Zika infection through other means.