|Zika virus disease is caused by a virus transmitted primarily by Aedes mosquitoes, which bite during the day / Photo Credit: US Southern Command|
A significant development for a vaccine against the Zika virus offers potential for the global elimination of the disease. Researchers from the University of Adelaide said the introduction of an effective vaccine will protect pregnant women and unborn children from the resulting congenital effects.
The findings, published in the international journal Science Advances, showcase the vaccine's potency in pre-clinical models using mice. Their development comes at a time when Zika continues to be a global threat—even after addressing previous outbreaks of the disease.
A novel vaccine
Zika is a mosquito-borne virus first discovered in monkeys in 1947 and found in humans five years later. Since then, outbreaks of the disease have been recorded in Africa, the Americas, Asia, and the Pacific.
While most infected adults experience mild symptoms, the virus can cause adverse effects on pregnant women and their babies. For instance, unborn children may have birth defects such as microcephaly or when the baby's head is significantly smaller than expected.
The researcher's vaccine against Zika may help prevent pregnant women from infection, thus protecting them and their unborn babies from the effects.
"Zika virus is extremely detrimental if you’re pregnant and there has been no therapy or vaccine available to date," Branka Grubor-Bauk, a lead author of the study, said in a statement. She noted that their work is the first to demonstrate how a T cell-based vaccine protects against Zika infection.
"Our vaccine offers an advantage over other vaccines in development by eliminating the ongoing concerns in the field about [the] enhancement of infection following exposure to dengue virus," she added.
|In a few cases, Zika can trigger paralysis or subsequent birth defects / Photo Credit: Egor Kamelev via Pexels|
The researchers injected the vaccine into albino mice aged six to eight weeks old, each of which received three doses over several weeks. By the end of the experiment, they found that the vaccine generated a strong immune response that protected the mice from Zika infection.
Years in the making
Based on the results, the vaccine pushes scientists closer to developing a method to protect humans from Zika. The researchers said the vaccine "could easily be manufactured on a large scale at low cost" and would be "safe for children and women of reproductive age."
The virology team has been working on the vaccine for years, generating developments as it progresses. Experiments to determine the potency of early vaccines and medications often use mice, since their biological, behavioral, and genetic characteristics are similar to those of humans and many symptoms of human conditions can be replicated in mice and rats.
However, such experiments don't always yield positive results when they move to human trials. With this, there's still a long way to go before researchers can introduce a vaccine against Zika and its adverse effects on the public.
"The next steps are to advance the vaccine to be ready for Phase I human clinical trials. This involves further pre-clinical studies which are vitally important to identify the most effective dosing and demonstrate protection against Zika infection in different pre-clinical models of the disease," Grubor-Bauk said.
"The goal is to de-risk and create an attractive technology with a strong IP position, for licensing or co-development with a commercial partner."
Still a threat
The breakthrough couldn't come at a better time as Zika remains a threat to public health—even if the latest outbreak was recorded five years ago. There were reports of the infection in all continents during the outbreak, with Brazil being the most affected.
In 2016, the state of Rio de Janeiro alone reported over 2,210 confirmed cases of Zika infections and over 120 million people were at risk, according to data from German statistics portal Statista. It adds that Zika infections led to 2,952 cases of microcephaly in newborns in Brazil.
The US was also one of the most affected countries during the outbreak. From 62 Zika infections in 2015, the number grew to over 5,000 the following year before dropping to 452 in 2017.
While the numbers of infected have dropped, the virus is still present in countries that were at the core of the outbreak. The virus strain that caused the epidemic was found two years ago in Africa for the first time, the New York Times reports.
Moreover, a World Health Organization report listed 61 countries that could host the mosquito that spreads the virus—the female Aedes aegypti—including densely populated giants like China, Egypt, and Pakistan.
Asian countries are also vulnerable to the effects of the infection. According to the New York Times, the strain that led the 2015 epidemic was the same strain that had been causing defects in Asia even before the outbreak.
Angola, Thailand, Vietnam, and Cape Verde are just some of the countries that reported newborns having Zika-related microcephaly.
"We thought of Zika as an inconsequential disease, but then it exploded in Brazil with devastating consequences," Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told the New York-based newspaper.
"The larger lesson for us is that we have to always be prepared for the emergence and re-emergence of viruses and microbes."