A new study reveals how the Zika virus hijacks a cell’s own housekeeping process to silence the very proteins that let it in. Researchers found that once Zika enters a host cell, it triggers autophagy — a self-preservation routine cells use to clear out unwanted molecules — to degrade two key receptors, AXL and TIM-1. By doing this, the virus not only secures its entry but also prevents infected cells from mounting an effective antiviral response. This clever tactic helps Zika maintain a foothold and spread without competition from newly produced viral particles.
The work, led by Shan-Lu Liu at The Ohio State University, appears in the May 23 issue of Proceedings of the National Academy of Sciences. Liu’s team looked at both African and Asian strains of Zika in three types of human cells: lung epithelial cells, trophoblasts (which support embryos), and glioblastoma brain cells. Across all these different cell types, they saw a consistent drop in AXL and TIM-1 levels after infection. That downregulation depended on autophagy, a finding that surprised the researchers because they had expected more common degradation pathways to be involved.
Zika has been a global concern since outbreaks in Africa, the Americas, and beyond, especially after the 2015 epidemic in Brazil linked the virus to babies born with microcephaly. While most adults show no or mild symptoms, the virus can cause serious neurological problems such as Guillain-Barré syndrome and myelitis.
Past studies pointed to AXL and TIM-1 as important “docking stations” on cell surfaces, where the virus latches on before slipping inside. Once inside, however, Zika seems to turn those docking stations into liabilities, since they could trigger the immune system unless they’re removed.
“Autophagy is a fundamental physiological mechanism to conserve cellular processes by degrading host components,” Liu explained. “It’s also called self-eating—cells need to remove damaged parts or misfolded proteins because they’re not good for the host.” In this study, Zika co-opts autophagy to clear away AXL and TIM-1, blocking the proteins’ antiviral signaling. Without those signals, infected cells can’t send out inflammatory alarms, giving the virus free rein to replicate.
To dig deeper, the researchers identified three Zika proteins on the viral membrane that prompt autophagy in host cells. Normally, those proteins help the virus enter cells or replicate its genetic material. Now, they’ve been shown to have a secondary function: dialing down cell-surface defenses. By targeting its own entry points, Zika avoids a situation called superinfection, where too many viral particles crowd a cell and kill it prematurely—an outcome that would be bad for the virus itself.
Although other viruses like HIV are known to silence their receptors, Zika stands out because it uses multiple viral proteins to achieve the same effect. This redundancy suggests that suppressing AXL and TIM-1 is crucial for Zika’s life cycle. It also adds a new layer to our understanding of how flaviviruses – Zika’s broader family, which includes West Nile, dengue, and yellow fever – interact with host cells. Some of these relatives may share similar tricks, though more work is needed to confirm that.
Still, questions remain about how these findings translate to animals and humans, where receptor use and tissue contexts can differ. For instance, earlier mouse studies showed that removing AXL didn’t stop Zika infection in live animals, hinting at alternative pathways the virus might exploit. Liu’s cell culture work offers a clear mechanism for receptor downregulation, but it will be important to test whether autophagy-driven suppression happens in infected tissues during real outbreaks.
Understanding these interactions is key to preparing for future viral threats. By mapping out how Zika wrests control of host defenses, researchers can look for new antiviral targets. If we can block the virus’s ability to trigger autophagy, we might restore the cell’s natural defenses and limit infection.
“The more important a host factor is to a virus, the more a virus is going to do to take control of it,” Liu said.
Looking ahead, Liu and colleagues plan to explore whether other flaviviruses use similar strategies, and to test potential inhibitors of this autophagy-based suppression. Such work could not only shed light on Zika’s biology but also inform broader efforts to combat mosquito-borne diseases. For now, this study brings us closer to unraveling how Zika manages to stay one step ahead of our cells’ defenses.
The study has been published in Proceedings of the National Academy of Sciences.
