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Saliva from the mosquito vector of flaviviruses is capable of changing the local immune environment, leading to an increase of flavivirus-susceptible cells at the infected bite site. Additionally, an antibody response towards specific salivary gland (SG) components changes the pathogenesis of flavivirus in human populations. To investigate if antigenic SG proteins are capable of enhancing Zika virus (ZIKV) infection, a re-emerging flavivirus primarily transmitted by the Aedes aegypti mosquito, we screened for antigenic SG proteins using a yeast display library, and demonstrate a previously undescribed SG protein, we term neutrophil stimulating factor 1 (NeSt1), activates primary mouse neutrophils ex vivo. Passive immunization against NeSt1 decreases pro-IL-1β and CXCL2 expression, prevents macrophages from infiltrating into the bite site, protects susceptible IFNAR-/-IFNGR-/- (AG129) mice from early ZIKV replication, and ameliorates viral-induced pathogenesis. These findings indicate that NeSt1 stimulates neutrophils at the mosquito bite site to change the immune microenviroment, allowing higher early viral replication and enhancing ZIKV pathogenesis. (156 Words) [ABSTRACT FROM AUTHOR]

Few animal models of Zika virus (ZIKV) infection have incorporated arthropod-borne transmission. Here, we establish an Aedes aegypti mosquito model of ZIKV infection of mice, and demonstrate altered vector competency among three strains, (Orlando, ORL, Ho Chi Minh, HCM, and Patilas, PAT). All strains acquired ZIKV in their midguts after a blood meal from infected mice, but ZIKV transmission only occurred in mice fed upon by HCM, and to a lesser extent PAT, but not ORL, mosquitoes. This defect in transmission from ORL or PAT mosquitoes was overcome by intrathoracic injection of ZIKV into mosquito. Genetic analysis revealed significant diversity among these strains, suggesting a genetic basis for differences in ability for mosquito strains to transmit ZIKV. The intrathoracic injection mosquito-mouse transmission model is critical to understanding the influence of mosquitoes on ZIKV transmission, infectivity and pathogenesis in the vertebrate host, and represents a natural transmission route for testing vaccines and therapeutics. (152 words) [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV) can be transmitted by mosquito bite or sexual contact. Using mice that lack the type I interferon receptor, we examined sexual transmission of ZIKV. Electron microscopy analyses showed association of virions with developing sperm within testes as well as with mature sperm within epididymis. When ZIKV-infected male mice were mated with naive female mice, the weight of fetuses at embryonic day 18.5 was significantly reduced compared with the control group. Additionally, we found ocular deformities in a minority of the fetuses. These results suggest that ZIKV causes fetal abnormalities after female mating with an infected male. [ABSTRACT FROM AUTHOR]