Have you ever stopped to think about how one might vaccinate a bat? It’s not a simple task, that’s for sure. You can’t just take them to a vet, and bats, well, they aren’t exactly organized about lining up for a shot.
A team of researchers from China might have figured out a potential solution. This could offer a new way to prevent diseases that jump from animals, particularly bats, to humans.
“Bats are reservoirs for some really deadly viruses, like Ebola, Nipah, Hendra, coronaviruses, and rabies,” mentions Aihua Zheng, a virologist at the Chinese Academy of Sciences. He adds that as time goes on, more bat-borne viruses are being discovered.
When these viruses make the leap to humans, the consequences can be severe, so there’s huge interest in finding ways to prevent these spillovers.
Some places have resorted to culling bats to manage the spread, but Zheng points out a flaw in that strategy. “Killing bats increases human contact with them, raising chances of infection,” he notes. Plus, exterminating bats can disrupt ecosystems because they help pollinate plants and control pests. Sadly, their populations are already declining due to habitat loss and disease.
In a recent paper published in the journal Science Advances, Zheng and his team propose a different kind of solution: vaccinating the bats themselves against these dangerous viruses. “By doing this, we’re not just protecting people; we’re also safeguarding the bats,” he explains.
They came up with some innovative ways to immunize the bats, including using mosquitoes that carry the vaccine!
“If we can vaccinate the population, we could significantly reduce or even eliminate virus transmission,” Zheng adds.
While this strategy is still in the early stages, it represents a promising advance for those fighting these diseases.
Using Mosquitoes as Vectors
The tricky part, Zheng explains, is figuring out how to effectively vaccinate bats.
In a previous study, researchers applied a topical vaccine that bats could lick off each other. While effective in a lab setting, scaling it up in the wild poses challenges—catching bats just isn’t that straightforward. So, they chose a different approach: using mosquitoes like tiny syringes. “We aim to transform the mosquito into a vaccination tool,” Zheng explains. They fed the mosquitoes blood infused with genetically modified vaccines targeting either Nipah or rabies. The vaccines then integrated into the mosquitoes’ bodies.
To test whether a mammal could pick up the vaccine from a mosquito, the researchers first tried it on mice and other rodents. The real test, however, came when they worked with actual bats. Catching some insect-eating bats from suburban Beijing was part of the plan. Zheng enjoys exploring caves, which is where he hopes to find some of them.
In the lab, they let either the mosquitoes bite the bats or had the bats consume the mosquitoes. After a few weeks, blood tests from the bats revealed antibodies. This indicates that the bats developed an immune response to the virus corresponding to the vaccine they had received.
Then they intentionally infected these bats, which had developed antibodies against rabies, with the actual rabies virus. In a typical scenario, this would have been fatal, but “most survived,” Zheng states.
He envisions a future where modified mosquitoes could be released into caves to vaccinate wild bats. One idea is to use a gentle airflow to keep the mosquitoes confined while allowing bats to freely enter and exit.
Alternative Approaches
Zheng does realize that the mosquito method won’t be universally applicable. “The world is a complicated place,” he notes, highlighting the difficulties in releasing modified insects in different environments. Hence, they devised a backup plan: a saline solution containing an oral rabies vaccine that bats in the lab eagerly drank. “When bats drink this water, they get vaccinated,” Zheng explains.
The results were encouraging, as this method also shielded the bats from rabies infections. “It really worked! I’m really excited about these results,” he exclaims.
Ausraful Islam, a veterinarian and expert in infectious diseases in Dhaka, Bangladesh, called the study “amazing.” Although he wasn’t part of the experiments, he highlighted the potential benefits for countries like Bangladesh, which face threats from bat-borne viruses. However, he believes more work is necessary before applying these techniques on a larger scale, especially regarding the longevity of immunity in bats and the feasibility of ongoing vaccination programs.
Zheng and his team are looking ahead, planning future studies and seeking international partners to help make this ambitious idea a reality.
