Zika and chikungunya viruses decrease salivation in Aedes aegypti mosquitoes

Aedes mosquitoes transmit viruses of global health concern through blood feeding. While biting, mosquitoes inject viruses but also saliva factors that modulate feeding and potentially viral transmission. However, studying this interplay is limited by our ability to quantify saliva release. Here, we developed a transgenic Aedes aegypti line that secretes fluorescent markers in saliva, enabling visualization of probing sites on human skin explants and quantification of salivation. Saliva secretion remained robust under diverse physiological conditions but was significantly reduced upon Zika or chikungunya virus infection. Nevertheless, virus release did not correlate with levels of saliva factors, suggesting decreased salivation does not lower chances of viral transmission. Our results bring perspective to the previously described increase in probing behavior in infected mosquitoes, indicating it may be caused by lower release of saliva factors. Thus, the negative impact of infection on salivation may have been selected to facilitate virus transmission.