The first live-attenuated vaccine candidate completely protects mice against Zika infection

April 10, 2017
Credit: University of Texas Medical Branch at Galveston

The first live-attenuated Zika vaccine still in the development stage completely protected mice against the virus after a single vaccination dose, according to new research from The University of Texas Medical Branch at Galveston and Instituto Evandro Chagas at the Ministry of Health in Brazil. The findings are currently available in Nature Medicine.

While a Zika infection typically results in mild or symptom-free infections in healthy adults and children, the risk of microcephaly and other diseases in the developing fetus is an alarming consequence that has created a worldwide health threat. Pregnant women who are infected with the Zika but never display any disease symptoms may still give birth to a baby with microcephaly.

An effective vaccine is urgently needed for women of childbearing age and travelers to areas where the virus has been reported. Since Zika virus could also be sexually transmitted, prevention of men from infection through vaccination could also halt Zika transmission and diseases.

Rapid and promising progress has been made toward a Zika vaccine. These developing vaccines have been made from an inactivated version of the Zika virus or subunits of the virus; these vaccine candidates have been shown effective in mice and nonhuman primates.

"We chose to pursue a vaccine made from live virus that has been sufficiently attenuated, or weakened, to be safe, and is able to illicit robust immune response to protect us from Zika virus infection. Such live-attenuated vaccine has the advantage of single-dose immunization, rapid and strong immune response and potentially long-lived protection," said UTMB's Pei-Yong Shi, senior author and the I.H. Kempner professor at the Department of Biochemistry and Molecular Biology. "A successful vaccine requires a fine balance between efficacy and safety - vaccines made from attenuated live viruses generally offer fast and durable immunity, but sometimes with the trade-off of reduced safety, whereas inactivated and subunit viruses often provide enhanced safety but may require several doses initially and periodic boosters. Therefore, a safe live-attenuated vaccine will be ideal in prevention of Zika virus infection, especially in developing countries."

To create the vaccine, the researchers engineered the Zika virus by deleting one segment of the viral genome. A similar approach has successfully been used to develop a dengue virus vaccine, which is currently in phase three clinical trials.

Shi explained that the data indicate that the vaccine the team is developing has a good balance between safety and efficacy. A single immunization with the produced strong immune responses and prevented the virus from infecting mice at all.

"Safety is a major hurdle when developing a live-attenuated vaccine. Our Zika vaccine showed promising safety profile in mice when compared with clinically approved live-attenuated vaccines, such as the yellow fever vaccine," Shi said.

"Vaccines are an important tool for preventing Zika virus transmission and microcephaly," said Pedro F. C. Vasconcelos, medical virologist and present director of the Evandro Chagas Institute and co-author. "This vaccine, the first live-attenuated vaccine for Zika, will improve the public health efforts to avoid the birth defects and diseases caused by Zika in countries where the virus is commonly found. The initial target of this is women of childbearing age, their sexual partners and children less than 10 years old.

Explore further: More evidence that Zika mRNA vaccines can stop viral replication in mice

More information: Chao Shan et al. A live-attenuated Zika virus vaccine candidate induces sterilizing immunity in mouse models, Nature Medicine (2017). DOI: 10.1038/nm.4322

Related Stories

More evidence that Zika mRNA vaccines can stop viral replication in mice

February 17, 2017
Vaccine developers have successfully protected mice against Zika by injecting synthetic messenger RNA that encodes for virus proteins into the animals. The cells of the mice then build parts of the virus, training the immune ...

Video: Responding to a crisis—a vaccine for Zika

March 30, 2017
While a new Gallup poll finds most Americans are not worried about Zika, the recent case of an infected baby born in San Diego demonstrates the virus is a very real issue in this country.

Immune molecule protects against Zika virus infection in animal models

March 14, 2017
A molecule naturally produced by the immune system protects mice and monkeys against Zika virus infection, an international team of researchers has found. Administering the molecule, called 25-hydroxycholesterol or 25HC, ...

Research teams hone in on Zika vaccines, but challenges remain

February 21, 2017
As public health officials warn that spring's warmer temperatures may herald another increase of Zika virus infections in the Caribbean and North and South America, researchers around the world are racing to develop safe ...

No women's Zika vaccine likely before 2020: WHO

February 1, 2017
About forty potential vaccines for the Zika virus are being tested, but none are likely to be available for women of childbearing age before 2020, the World Health Organization said Wednesday.

US enrolls volunteers in large test of possible Zika vaccine

March 31, 2017
U.S. health officials have begun enrolling volunteers for critical next-stage testing of an experimental vaccine to protect against Zika, the mosquito-borne virus that can cause devastating birth defects in pregnant women.

Recommended for you

Groundbreaking investigative effort identifies gonorrhea vaccine candidates

September 19, 2017
Researchers at Oregon State University have identified a pair of proteins that show promise as the basis for a gonorrhea vaccine.

Snail fever progression linked to nitric oxide production

September 14, 2017
Bilharzia, caused by a parasitic worm found in freshwater called Schistosoma, infects around 200 million people globally and its advance can lead to death, especially in children in developing countries.

Systems analysis points to links between Toxoplasma infection and common brain diseases

September 13, 2017
More than 2 billion people - nearly one out of every three humans on earth, including about 60 million people in the United States - have a lifelong infection with the brain-dwelling parasite Toxoplasma gondii.

Study clears important hurdle toward developing an HIV vaccine

September 13, 2017
An international team of researchers has demonstrated a way of overcoming one of the major stumbling blocks that has prevented the development of a vaccine against HIV: the ability to generate immune cells that stay in circulation ...

As 'flesh-eating' Leishmania come closer, a vaccine against them does, too

September 13, 2017
Parasites that ulcerate the skin, can disfigure the face, and may fatally mutilate its victim's internal organs are creeping closer to the southern edges of the United States.

Promising clinical trial results could give doctors a new tool against drug-resistant strains of malaria parasite

September 13, 2017
Tulane University researchers have developed a new drug that is effective against non-severe cases of malaria, according to results from an FDA-supervised clinical trial published in the latest issue of The Lancet Infectious ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.