Starpharma (ASX: SPL) has announced that the VivaGel active, astodrimer sodium (SPL7013), has been shown to have potent antiviral activity against the Zika virus in laboratory studies.
According to the company, the studies showed near complete antiviral protection at SPL7013 concentrations significantly below that used in the VivaGel condom.
The World Health Organisation has declared the Zika virus outbreak a global emergency. It now affects more than 40 countries in total - 20 countries in the Americas, most of the Caribbean and several in the Pacific.
The most significant outbreak, and resulting effects on babies, has been reported in Brazil, where an estimated one million people have already been infected with Zika.
Although Zika is a mosquito-borne virus, it is now also confirmed to be a sexually transmitted infection. The US Centers for Disease Control and Prevention has reported more than 425 travel-associated cases of Zika virus and there are now a growing number of people infected through sexual transmission by travellers returning from affected areas.
Zika virus infection is of particular concern during pregnancy. Infection during pregnancy is a cause of microcephaly and other severe foetal brain defects, and has been linked to problems in infants, including eye defects, hearing loss and impaired growth.
The US Centers for Disease Control and Prevention has advised that the virus can be spread during sex regardless of whether the man has symptoms or not. Its guidelines recommend that if a male is infected, non-pregnant couples should use a condom every time they have sex to prevent possible infection or abstain from sex for at least six months.
For pregnant couples, this recommendation also applies but for the duration of the pregnancy.
The VivaGel condom, marketed in Australia as the Dual Protec condom by Ansell, contains the antiviral VivaGel active. The physical barrier of the condom provides primary protection against sexually transmitted infections), while VivaGel is included in the condom lubricant as an antiviral agent that has been proven, in laboratory studies only, to inactivate HIV, HSV and HPV.
The company said that, in view of the potent antiviral activity identified for the VivaGel active against Zika virus, it is now investigating the inclusion of Zika in the list of viruses inactivated by the VivaGel condom.
“There is currently no vaccine or therapy available for Zika virus. Given sexually transmitted infection is of increasing importance, the potent activity of the VivaGel active against Zika virus could prove very important from a public health standpoint and a significant commercial opportunity,” said Starpharma CEO, Dr Jackie Fairley.