Zika Virus ZIKV
Overview
- Zika virus is an emerging pathogen that is transmitted among nonhuman primates and humans by Aedes mosquitoes.
- Principal Reservoir Host(s): Nonhuman primates (Macaca, Pongo spp.)
- Family : Flaviviridae
- Genus : Flavivirus
Virology
- 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 known viruses in the Spondweni virus clade.
- A positive-sense RNA genome can be directly translated into viral proteins.
- As in other flaviviruses, such as the similarly sized West Nile virus, the RNA genome encodes seven nonstructural proteins and three structural proteins. One of the structural proteins encapsulates the virus.
- The RNA genome forms a nucleocapsid along with copies of the 12-kDa capsid protein.
- The nucleocapsid, in turn, is enveloped within a host-derived membrane modified with two viral glycoproteins.
- Viral genome replication depends on the synthesis of double sided RNA from the single stranded positive sense RNA (ssRNA(+)) genome followed by transcription and replication to provide viral mRNAs and new ssRNA(+) genomes.
Pathogenesis
- Zika virus ZIKV replicates in the mosquito’s midgut epithelial cells and then its salivary gland cells.
- After 5–10 days, the virus can be found in the mosquito’s saliva. If the mosquito’s saliva is inoculated into human skin, the virus can infect epidermal keratinocytes, skin fibroblasts in the skin and the Langerhans cells.
- The pathogenesis of the virus is hypothesized to continue with a spread to lymph nodes and the bloodstream.
- Flaviviruses generally replicate in the cytoplasm, but Zika antigens have been found in infected cell nuclei.
Transmission
Zika virus ZIKV is transmitted to human or human to human as following:
- Mosquito (Aedes mosquitoes) bite
- Sexual transmission
- Pregnancy transmission from an infected mother to her fetus during pregnancy or at delivery
- Blood transfusion
Disease
- Zika virus ZIKV infection cause Zika virus disease (ZVD) which is characterized by influenza-like clinical signs, including fever (Zika fever), headaches, and malaise.
