Zika virus (ZIKV) is a member of the virus family Flaviviridae and the genus Flavivirus. It is spread by daytime-active Aedes mosquitoes, such as A. aegypti and A. albopictus.] Its name comes from the Zika Forest of Uganda, where the virus was first isolated in 1947. Zika virus is related to the dengue, yellow fever, Japanese encephalitis, and West Nile viruses. Since the 1950s, it has been known to occur within a narrow equatorial belt from Africa to Asia. From 2007 to 2016, the virus spread eastward, across the Pacific Ocean to the Americas, leading to the 2015–16 Zika virus epidemic.
The infection, known as Zika fever or Zika virus disease, often causes no or only mild symptoms, similar to a very mild form of dengue fever. While there is no specific treatment, paracetamol (acetaminophen) and rest may help with the symptoms. As of 2016, the illness cannot be prevented by medications or vaccines. Zika can also spread from a pregnant woman to her fetus. This can result in microcephaly, severe brain malformations, and other birth defects. Zika infections in adults may result rarely in Guillain–Barré syndrome.
About the Virus
The Zika virus belongs to the Flaviviridae family and the Flavivirus genus, and is thus related to the dengue, yellow fever, Japanese encephalitis, and West Nile viruses. Like other flaviviruses, Zika virus is enveloped and icosahedral and has a nonsegmented, single-stranded, 10 kilobase positive-sense RNA genome. It is most closely related to the Spondweni virus and is one of the two viruses in the Spondweni virus clade.
Mosquito that spreads Zika
Zika is primarily spread by the female Aedes aegypti mosquito, which is active mostly in the daytime, although researchers have found the virus in common Culex house mosquitoes as well. The mosquitos must feed on blood in order to lay eggs. The virus has also been isolated from a number of arboreal mosquito species in the Aedes genus, such as A. africanus, A. apicoargenteus, A. furcifer, A. hensilli, A. luteocephalus and A. vittatus, with an extrinsic incubation period in mosquitoes of about 10 days.
Vaccine development for the Zika Virus
Effective vaccines have existed for several viruses of the flaviviridae family, namely yellow fever vaccine, Japanese encephalitis vaccine, and tick-borne encephalitis vaccine, since the 1930s, and dengue fever vaccine since the mid-2010s. World Health Organization (WHO) experts have suggested that the priority should be to develop inactivated vaccines and other non-live vaccines, which are safe to use in pregnant women and those of childbearing age.
The US NIH Vaccine Research Center began work towards developing a vaccine for Zika per a January 2016 report. Bharat Biotech International (India) reported in early February 2016, that it was working on vaccines for Zika using two approaches: "recombinant", involving genetic engineering, and "inactivated", where the virus is incapable of reproducing itself but can still trigger an immune response with animal trials of the inactivated version to commence in late February. As of March 2016, 18 companies and institutions internationally were developing vaccines against Zika, but none had yet reached clinical trials. The first human trial for Zika vaccine, a synthetic DNA vaccine (GLS-5700) developed by Inovio Pharmaceuticals, is approved by FDA in June 2016. Interim results of the Phase 1 study is expected in later 2016. Nikos Vasilakis of the University of Texas Medical Branch (UTMB) predicted that it may take two years to develop a vaccine, but ten to twelve years may be needed before an effective Zika vaccine is approved by regulators for public use.