Zika virus
المؤلف:
Baijayantimala Mishra
المصدر:
Textbook of Medical Virology
الجزء والصفحة:
2nd Edition , p239
2025-11-29
51
Zika virus, a member of Flavivirus, was known as a causative agent of mild fever in a limited geographical area. Recently the virus has gained importance because of its increase in geographical range as well as expanding clinical spectrum including neurological involvement and severe congenital malformation.
VIRUS
Zika virus is a mosquito borne Flavivirus belongs to the spondwoni serocomplex of Flavivirus genus within the family Flaviviridae. It is an enveloped virus with icosahedral symmetry containing single stranded, positive sense RNA genome of 10,794 base pair in length. The genome has a single open reading frame (ORF) flanked by 5’and 3’ non-coding region (5’NCR and 3’NCR). The open reading frame codes for a single poly protein which gets cleaved into three structural proteins and seven non-structural proteins. Structural proteins are capsid, premembrane/membrane and envelop and non-structural proteins are NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5.
Phylogenetic studies have shown that the Zika virus has two major lineages: African and Asian. African strains have two groups: Prototype MR766 Ugandan cluster and Nigerian cluster. Asian lineage consisted of Malaysian strains, 2007 Micronesian strains. Based on the phylogenetic results, it has been suggested that the virus had originated from East Africa, then moved to West Africa through different introductions. From West Africa, it came to Asia in around 1940 and then circulated in different region. The current American isolates are similar to Asian genotype and most closely related to Yap, Cambodia, Thailand and French Polynesia. The circulation of Zika virus of different genotypes might have impact on diagnostic assay and designing of vaccine.
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