Zika researchers reveal antibody treatment that could protect infected pregnant mothers

Zika breakthrough as researchers reveal antibody treatment that could protect infected pregnant mothers and their babies

Research 'proof of principle that Zika virus during pregnancy is treatable'

Tested on pregnant mice, the treatment reduced levels of the virus in the mothers, and also protected their pups from the ravages of the virus

Researchers say in could be ready for human trials in a year

Published: 11:00 EST, 7 November 2016 | Updated: 15:52 EST, 7 November 2016

A new study of the Zika virus in mice raises hope for a way to protect pregnant women and their babies from the possible repercussions of being infected, U.S. researchers said on Monday.

The experimental treatment is derived from antibodies taken from the blood of people who have recovered from Zika infections.

Tested on pregnant mice, the treatment reduced levels of the virus in the mothers, and also protected their pups from the ravages of the virus.

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Researchers hailed the study as 'proof of principle that Zika virus during pregnancy is treatable'. Tested on pregnant mice, it reduced levels of the virus in mothers, and protected pups.

HOW IT WORKS

In the study, the researchers screened 29 Zika-specific antibodies taken from the white blood cells of patients who recovered from Zika infections caused by strains in Asia, Africa and the Americas.

They found one, called ZIKV-117, that neutralized all of the strains.

The team then tested the antibodies in pregnant mice one day before and a day after infection with Zika.

Zika, spread primarily through mosquitoes, has been known to cause birth defects in infants whose mothers have been infected during pregnancy.

'This is proof of principle that Zika virus during pregnancy is treatable, and we already have a human antibody that treats it, at least in mice,' said Dr. Michael Diamond of Washington University School of Medicine in St. Louis, co-author of the study published on Monday in the journal Nature.

In the study, the researchers screened 29 Zika-specific antibodies taken from the white blood cells of patients who recovered from Zika infections caused by strains in Asia, Africa and the Americas.

They found one, called ZIKV-117, that neutralized all of the strains.

The team then tested the antibodies in pregnant mice one day before and a day after infection with Zika.

A researcher holds a tray of Zika virus growing in animal cells at Washington University School of Medicine in St. Louis. There is no treatment available to block Zika virus in a pregnant woman from infecting her fetus and potentially causing severe birth defects. But researchers have identified a human antibody that prevents, in pregnant mice, the fetus from becoming infected and the placenta from being damaged.

'The antibody reduces virus in the mother and also in the fetus, and it protects against placental and fetal damage,' said Dr. James Crowe of Vanderbilt University School of Medicine.

'These naturally occurring human antibodies isolated from humans represent the first medical intervention that prevents Zika infection and damage to fetuses,' said Crowe.

'We're excited because the data suggests we may have antibody treatments in hand that could be developed for use in pregnant women,' he said.

ZIKA infection could cause lasting infertility and lead to men's testicles shrinking, medical researchers warned in a recent study (stock image)

Crowe said he intends to keep pressing ahead, licensing the product to commercial partners.

He believes it can be ready for human trials in nine to 12 months, 'if we go flat out.'

Still, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which funded the research, cautioned that not everything that works in mice works in people.

However, he said: 'The very fact that you did get a positive result in the mouse model is a pretty good impetus to take it to the next step, which could be a non-human primate, and see if the same things works in a non-human primate.'

Vanderbilt is in the process of licensing the antibody to privately held Ridgeback Biotherapeutics, which has begun ramping up production of the antibodies in a facility designed to meet FDA manufacturing specifications.

'The antibody reduces virus in the mother and also in the fetus, and it protects against placental and fetal damage,' said Dr. James Crowe of Vanderbilt University School of Medicine (pictured).

As a treatment, antibodies for Zika could be given to pregnant women as infusions to offer temporary protection for the fetus.

The protection would last about three weeks, before another infusion is needed.

Getting support for a treatment for use in pregnant women may prove difficult, however.

'With many things outstanding in our knowledge gap with Zika, therapeutics that would be used in pregnant women to benefit an infected fetus is high risk and there is a lot of development work to be done to ensure those drugs could be used safely,' Rick Bright, who is leading Zika medical countermeasure development for Office of the Assistant Secretary for Preparedness and Response and BARDA, said in an emailed statement.

Bright said the agency might be interested in supporting the treatment in later-stage development, after it has been proven successful in early-stage studies.

'It's important to keep in mind that 80 percent of people do not even know that they have been infected with Zika, so we are focused first on vaccines to prevent infection, diagnostics to determine if someone has been infected, and screening to prevent the spread of the virus through the blood supply,' he said.

LATEST ON ZIKA: WHAT WE KNOW ABOUT THE VIRUS

HOW DO PEOPLE GET IT?

MOSQUITO BITES

Zika is transmitted to people through the bite of infected female mosquitoes, primarily the Aedes aegypti mosquito.

It is the same type that spreads dengue, chikungunya and yellow fever.

The Pan American Health Organization (PAHO) said Aedes aegypti mosquitoes are found in all countries in the Americas except Canada and continental Chile.

Zika will likely reach all countries and territories of the region where Aedes mosquitoes are found.

SEX

The virus can also be transmitted through sex, from either a male or female partner who has been infected.

BLOOD TRANSFUSION

A few cases of apparent infection via blood transfusion have been reported.

PREGNANCY

A mother can pass the virus to her unborn fetus.

Current research indicates the greatest microcephaly risk is associated with infection during the first trimester of pregnancy, but health officials have warned an impact could be seen in later weeks.

Recent studies have shown evidence of Zika in amniotic fluid, placenta and fetal brain tissue.

HOW DO YOU TREAT ZIKA?

There is no treatment or vaccine for Zika infection.

Companies and scientists are racing to develop a safe and effective vaccine for Zika.

However, a preventative shot is not expected to be ready for widespread use for at least two or three years.

WHAT ARE THE DANGERS?

BIRTH DEFECTS

Microcephaly

The CDC concluded that infection with the Zika virus in pregnant women is a cause of the birth defect microcephaly.

Microcephaly is a condition defined by unusually small heads that can result in developmental problems, and other severe brain abnormalities in babies.

The CDC said that since the causal relationship had been established, several important questions must still be answered with studies that could take years.

The World Health Organization in an updated assessment said the 'most likely explanation' is that Zika virus infection during pregnancy is a cause of congenital brain abnormalities including microcephaly.

Brazil recently reported 1,949 confirmed cases of microcephaly believed to be linked to Zika infections in pregnant women.

It is investigating more than 3,030 suspected cases of microcephaly.

Guillain-Barre syndrome

The WHO also updated its guidelines to say the infection is a trigger of Guillain-Barre syndrome (GBS), a rare neurological disorder that can result in paralysis.

Its previous statement, based on a rapid assessment of evidence, said there was strong scientific consensus that Zika virus caused GBS, microcephaly and other neurological disorders.

WHAT ARE THE SYMPTOMS?

People infected with Zika may have a mild fever, skin rash, conjunctivitis, muscle and joint pain and fatigue that can last for two to seven days.

But as many as 80 per cent of people infected never develop symptoms.

HOW CAN ZIKA BE CONTAINED?

Efforts to control the spread of the virus focus on eliminating mosquito breeding sites and taking precautions against mosquito bites such as using insect repellent and mosquito nets.

U.S. and international health officials have advised pregnant women to avoid travel to Latin American and Caribbean countries, sections of Miami, Florida in the United States and Singapore where they may be exposed to Zika.

They are also advising that men and women who have traveled to Zika outbreak areas use condoms or abstain from sex for six months to prevent sexual transmission of the virus.

HOW WIDESPREAD IS THE OUTBREAK?

Active Zika outbreaks have been reported in at least 59 countries or territories, most of them in the Americas, according to the CDC. Brazil has been the country most affected.

Africa: 1 country

Cape Verde

Americas: 49 countries

Anguilla, Antigua and Barbuda, Argentina, Aruba, The Bahamas, Barbados, Belize, Bolivia, Bonaire, Brazil, British Virgin Islands, Cayman Islands, Colombia, Costa Rica, Cuba, Curaçao, Dominica, Dominican Republic, Ecuador, El Salvador, French Guiana, Grenada, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Mexico, Nicaragua, Panama, Paraguay, Peru, Saba, Puerto Rico, Saint Barthelmy, Saint Lucia, Saint Martin, Saint Vincent and the Grenadines, Saint Eustatius, St. Maarten, St. Kitts and Nevis, Suriname, Trinidad and Tobago, Turks and Caicos, United States, U.S. Virgin Islands, Venezuela.

Asia: 1 country

Singapore

Oceania/Pacific Islands: 8 countries

American Samoa, Fiji, Kosrae, Federated States of Micronesia, Marshall Islands, New Caledonia, Papua New Guinea, Samoa, Tonga.

HISTORY OF ZIKA

The Zika virus is found in tropical locales with large mosquito populations.

Outbreaks of Zika have been recorded in Africa, the Americas, Southern Asia and the Western Pacific.

The virus was first identified in Uganda in 1947 in rhesus monkeys and was first identified in people in 1952 in Uganda and Tanzania, according to the WHO.

ANY OTHER ZIKA-RELATED COMPLICATIONS?

Zika has also been associated with other neurological disorders, including serious brain and spinal cord infections.

The long-term health consequences of Zika infection are unclear.

Other uncertainties surround the incubation period of the virus and how Zika interacts with other viruses that are transmitted by mosquitoes, such as dengue.