The World Health Organisation (WHO) has declared the Zika virus to be a global public health emergency. This was due to the rapid spread of the virus in the Americas, and concerns about its link to a rise in severe neurological diseases. Most notably, some pregnant women who have contracted the Zika virus have given birth to infants with brain development issues caused by a condition called microcephaly.
The virus is rapidly spreading in new geographic areas such as the Americas, where people have not been previously exposed to the disease and therefore have little immunity to it. In April 2016, the Centers for Disease Control (CDC) announced that a rise in severe neurological disorders, especially in children, has been linked to the Zika virus. Some pregnant women who have contracted the Zika virus have given birth to infants with a condition called microcephaly, which results in brain development issues typically leading to severe mental deficiencies. In other cases, paralysis and other neurological problems can occur, even in adults.
Even though there are also efforts to eradicate the mosquitoes that spread Zika, the disease is likely to continue to spread rapidly in the Americas, because the general human population in this region has not been exposed to the virus previously and therefore has little immunity to it. In addition, the mosquitoes that spread Zika are difficult to eradicate because they tend to hide inside homes, which makes widespread insecticide spraying strategies less effective. Many mosquitoes have also become increasingly resistant to common insecticides. In addition, unlike most mosquitoes, the female Aedes aegypti mosquito feeds on people during the daytime, which makes it more difficult to prevent this form of Zika virus transmission.
CDC map reporting areas with active Zika Virus transmission, May 9th, 2016.
What is Zika?
The Zika virus is a member of the flavivirus genus, which includes dengue, yellow fever, West Nile viruses and others – viruses which are mostly transmitted to humans by a mosquito or tick bite. The Zika virus is transmitted primarily by two kinds of mosquitos: the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus). Sexual transmission of the Zika virus has also been recently confirmed, as well as transmission via the blood. Urine and saliva have been found to contain the virus, too.
CryoEM structure of the Zika virion
Although there are also efforts to eradicate the Aedes mosquitoes that spread Zika, the disease is likely to continue to spread rapidly in the Americas, because the general human population in this region has not been exposed to the virus previously and therefore has little immunity to it. In addition, the Aedes aegypti mosquito is more difficult to eradicate than other types of mosquitoes, because it tends to hide inside homes, which makes widespread insecticide spraying strategies less effective. Many mosquitoes have also become increasingly resistant to the insecticides that are used to try to kill them.
Aedes aegypti mosquito
The symptoms of a Zika infection are usually mild, consisting of fever, rash, joint pains, conjunctivitis (red eyes), headache and/or swollen lymph nodes. However, the link between Zika virus in pregnant women and microcephaly in fetuses and newborns has prompted several countries to recommend delaying pregnancy in affected areas until more is understood. More effective solutions are needed to combat the Zika epidemic.
Main symptoms caused by Zika virus
A link between Zika virus in expectant women and microcephaly in fetuses and newborns was confirmed by the Centers for Disease Control in April 2016. Microcephaly is a condition in which a child’s brain fails to develop properly in the womb, often leading to diminished brain size, impaired cognitive ability, motor control problems, seizures and related symptoms.
Other neurological conditions suspected of being associated with Zika include:
- Guillain–Barré syndrome, which causes sudden muscle weakness and even paralysis in adults.
- Myelitis, which is an infection of the spinal cord.
- Meningoencephalitis, an inflammation of the brain and surrounding tissues, usually caused by infection.
These neurological effects have caused great concern and prompted the World Health Organization to form a Zika Emergency Committee to address the problem.
A baby with microcephaly (left) compared to a baby with a normal head size (right)
Guillain-Barré Syndrome causes damage in myelin sheath (sheath which surrounds the axons of many peripheral nerves), which causes paralysis.
Meningoencephalitis (an inflammation of the brain and surrounding tissues)
Myelitis (an infection of the spinal cord)
History and Research
Even though the virus was first identified in 1947, little research has been done until the recent outbreak in the Americas. The latest version of the Zika virus genome was sequenced in 2016, and scientists are using that genetic information to work toward determining the proteins involved in the disease and what their structures are, which could help in the development of a vaccine or antiviral medicines.
There is currently no vaccine to prevent infection with the Zika virus, nor is there any known antiviral drug to treat patients who have contracted the virus. Scientists do not yet have computational research methods that could take advantage of World Community Grid to develop a vaccine. But World Community Grid’s vast computational resources can instead play a role in helping researchers discover and develop antiviral drugs to combat Zika.
Developing Drug Treatments to Combat Zika
The OpenZika project aims to discover antiviral drugs to fight Zika in people who are already infected. To discover and develop these drugs more rapidly, scientists need to evaluate millions of chemical compounds to determine which might be effective at disabling the proteins a virus needs to reproduce or to infect cells. This often begins with determining the crystal structure, at the atomic scale, of these key proteins, then screening chemical compounds to see which can bind, or dock, to the protein and potentially disable it. To conduct such a screening process in a “wet laboratory” is very expensive and time consuming. That is where World Community Grid can help—by allowing researchers to use virtual screening techniques to systematically evaluate millions of compounds against many different Zika proteins. The researchers can then predict which compounds are more likely to be effective in subsequent wet lab tests that measure Zika virus replication or the ability of the virus to infect cells.