N-glycosylation on E protein and temperature regulate Zika virus infection in Aedes aegypti and Aedes albopictus mosquito cell

2018-07-26Zika virus (ZIKV) is a member of the virus family Flaviviridae and is transmitted by Aedes mosquitoes, such as A. aegypti and A. albopictus. Being associated with serious neurological and developmental pathologies, like congenital malformation during pregnancy and Guillain-Barré syndrome, ZIKV has rapidly spread reaching a global distribution pattern similar to that of dengue virus. Using the single-cycle ZIKVrep-based VLPs which co-expressed the strain-specific structural (CprME) and identical non-structural (NS1toNS5) proteins, it has been found that ZIKVs isolated in Africa could infect mosquito C6/36 or Aag-2 cells more efficiently than that isolated in Southeast Asia or in South America. We further confirm that the different infectivity among various strains of ZIKV is attributed to N-linked glycosylation of ZIKV enveloped (E) protein. Sequence analysis of different clinical and lab isolated strains has shown the existence of conserved N-glycosylation motif on domain I of protein E, which is common to all flavivirus. Infectivity of South American lineage ZIKVs in mosquito cells is strongly enhanced upon removing N-linked glycosylation by either introducing mutations or exogenous enzyme digestion. In contrast to mosquito cells, similar phenotypes could not be observed in human glioblastoma SNB-19 cells. Our study also shows that domain III of E protein is the receptor binding site for both human glioblastoma SNB-19 cells and Aedes mosquito C6/36 cells. For both strains of ZIKV with or without E protein glycosylation site, infectivity is significantly increased in 37°C compared with 28°C and this is post-entry phenotype of ZIKV infection. Decrease of environmental temperature can play an important role in suppression of ZIKV infection in mosquito cells, which may potentially become a key in control of the viral transmission and spread