Zika virus transmission in Aedes aegypti: a systematic study on the ability of mosquitoes to transmit the virus horizontally and vertically.

Zika virus (ZIKV) is a mosquito-borne virus belonging to the genus Orthoflavivirus, and the family Flaviviridae. It commonly presents with febrile-like symptoms, neurological issues, and pregnancy complications in humans. Currently, there is no commercial vaccine or specific treatment available to prevent ZIKV infection. Therefore, controlling the epidemic's spread relies on preventing mosquitoes from transmitting the virus. Although various studies have explored the transmission of ZIKV between mosquitoes and vertebrate hosts, comprehensive research on potential mosquito-to-mosquito transmission of ZIKV remains limited. In this study, we conducted systematic laboratory investigations to assess the ability of ZIKV to spread among mosquitoes, and to evaluate the impact of ZIKV infection on mosquito development. Our findings revealed that ZIKV can be transmitted between Aedes aegypti mosquitoes both vertically and horizontally, through oviposition and contact between mosquitoes of the same or opposite sex. Additionally, we observed that ZIKV infection resulted in a reduction in the number of mosquito eggs but an increase in their size. The widespread distribution of ZIKV in infected mosquitoes and the altered levels of hormone related genes following viral infection were noted, which may contribute to viral transmission among mosquitoes and affect mosquito development. This research provides systematic experimental evidence of ZIKV transmission among mosquitoes, which is crucial for developing novel strategies to disrupt the spread of orthoflaviviruses and other mosquito-borne pathogens.