Zika virus, an epidemic emerged as a new global threat
Zika virus (ZIKV),belonging to Flaviviridae,is a mosquito borne arbovirus.ZIKV is highly homologous to dengue virus,sharing 60％ nucleic acid and 55％ amid acid sequence identity.Cryo-EM structure of ZIKV suggests it's similar to other major flaviviruses including dengue virus,West Nile virus and yellow fever virus.Several Aedes mosquitoes are capable of transmitting ZIKV in the field,of which Aedes aegypti is the primary vector for human.Since the symptom caused by ZIKV infection is very similar to dengue virus and chikungunya virus,it's easily misdiagnosed and the ZIKV epidemic is underestimated.Although,entomological and virologic surveillance have reported ZIKV in countries of Africa and Asia,few severe human cases were reported until 2007,when a ZIKA fever epidemic took place in Yap Island in the Pacific Ocean.After that,ZIKV was spread across the Pacific Ocean and landed South America in 2014,bringing a ZIKV pandemic to Brazil.Molecular epidemiology study suggests ZIKV could be divided into African lineage and Asian lineage.The divergence between the two lineages is much lower compared to dengue virus which can be divided into four serotypes.The strains from Pacific Ocean islands to South America were derived from the Asian lineage.Because of the large amount of international traveler and business,ZIKV has been identified in more and more countries around the world.Indeed,three cases were reported in China recently and several virus strains were also recovered from the samples of patients.Both the basic and application research of ZIKV is neglected because it's considered as a mild dengue-like virus over long periods.But,during the evolution of ZIKV in new region and new ecosystem,virus transmission is changing.In the 2007 Gabon break,more aggressive vector Aedes albopictus was involved in human transmission beside Aedes aegypti,which made the control strategy even complicated.Fatal cases appeared at Yap islands in 2007 and even more in the recent South America epidemic.The possible association between ZIKV fever and microcephaly causes panic in the whole world.Both ZIKV virus and antibody are detected in fetuses with microcephaly.Using the newly developed mouse model of ZIKV,high loads of virus are detected in the brain and spinal cord which is inconsistent with the evidence that ZIKV causes neurodevelopmental defects in human fetuses.The testes of mice has the highest ZIKV viral loads,which is relevant to sexual transmission.Effective vaccine and therapeutic medicine are in urge need for the control of ZIKV.Here we briefly reviewed the current epidemic and molecular evolution of ZIKV.We also introduced the virology and immunology of other intensively studied flavivirus mainly dengue virus.The progress of vaccine and drug development of flavivirus is also summarized here.
NETL
NSTL
万方数据
维普
