Mosquitoes as flying syringes

Plus the secret to immortality, disease-causing fungi on Indian apples, and whales that walked on land.

Oct 08, 2022

It’s been a while since I last posted — and a lot has happened in the world and in my life since. I want to first take the opportunity to wish you all Shubho Bijoya during the festive season!

It’s been a rather hectic time for me since I returned from India in August. I revived my original Twitter account. I got my bivalent COVID-19 booster shot. After fifteen years helping to build scientific communities globally and launching journals at the world’s largest professional science organization, I took on a new role at an organization that’s fits my own scientific background.

The Nobel Prizes were awarded recently and an acquaintance won (deservedly, I might add, and in a field that I’m familiar with). Speaking of Nobel Prizes, we take antibiotics for granted but there were different ways of treating infectious diseases before their discovery: a form of treatment known as malariotherapy, won Julius Wagner-Jauregg the Nobel Prize in 1927. Essentially, before the discovery of penicillin, if someone suffered nerve damage from syphilis they were prescribed a “clinical course of malaria”! There are also other controversial awards in science disciplines such António Egas Moniz winning for the therapeutic value of the lobotomy.

I also wrote a newsletter two years about work by Svante Pääbo (winner of the Nobel Prize in Medicine) on the link between severe COVID-19 and Neanderthal genes.

Mosquitos as flying vaccine syringes

File this one under “cool but unlikely to be used anytime soon.”

Anopheles freeborni mosquito pumping blood.

Image source: CDC

Let’s face it blood-sucking mosquitoes are a menace. Because they’re so good at biting people, they also serve as inspiration for the design of needles that allow drawing of blood relatively painlessly without damage of tissues in the skin.

In a column in Hindustan Times, I write about a study that showed mosquitoes can be used to administer a live vaccine against malaria. As I write in the piece —

There’s a bit of history to this idea. In 2010, a group of Japanese scientists genetically engineered mosquitoes that made a protein that could act as a vaccine to prevent leishmaniasis.
The idea received a lot of press coverage at the time, including in prestigious media outlets like Technology Review and Science. But serious technical challenges to creating the mosquitoes made the approach unfeasible for actual use.
There was also the concern of letting mosquitoes loose that could bite people and inject them with a medical product such as a vaccine without their explicit informed consent.
But ultimately the biggest issue was prosaic. Mosquitoes are unpredictable. They bite some people a lot more than they bite others. It would be technically difficult to dose vaccines based on the whimsical feeding patterns of mosquitoes. Some people might never get the right amount of vaccine, while others might get way more than they would need for protection.
In the study published in Science Translational Medicine, mosquitoes were infected with malaria parasites lacking three critical genes. These three genes are needed for malaria to occur in humans.
Study volunteers received around 200 bites per sitting on their arms. The total vaccine was administered through 1,000 mosquito bites! If that sounds alarming then the researchers reassure that even though some people had reactions to mosquito bites, these were usually temporary.
The researchers then subjected volunteers to “controlled human malaria infection” about a month after their final series of mosquito-bite vaccinations. Basically, what happened is that mosquitoes which have normal malaria-causing parasites bit study volunteers. If a volunteer developed disease, antimalarials were provided to cure illness.
The researchers found that about half of those who were vaccinated by mosquito bites were protected completely against infection. This number may seem low, but the scientists were not discouraged that the experiment didn’t result in even greater efficacy.
Though their experiments show that vaccine delivery by mosquitoes does actually work, there are drawbacks that limit practical use of this method. Much of the vaccine stays in the skin after a mosquito bite instead of going to other parts of the body where it might elicit a stronger immune response.
So ultimately, even if this malaria vaccine gets approval for broader use, it is unlikely to be actually delivered by hundreds or thousands of mosquito bites. Injections by syringes offer several benefits that can’t be dismissed just yet.

The secrets of the immortal jellyfish

There’s an animal that might live forever — at least one one sense of the world.

Now, we know more about how this elusive animal achieves this feat. In my second column last month I wrote about new research that explains how it’s all in the genes.

The researchers found that there probably isn’t a single switch that confers immortality, but a plethora of processes that contribute (many in unknown ways) to this biological feat. Some of these processes, however, can be triggered in other animals too to slow down ageing, though perhaps not to the exact same extent.
Among the genes that are likely to help in rejuvenation in the “immortal jellyfish” are multiple copies of genes that give rise to proteins that protect and repair DNA. There are also mechanisms that the jellyfish has acquired that help them to protect the ends of chromosomes (known as telomeres) which can fray like the ends of shoelaces. There are also extra genes for factors that allow certain kinds of cells to change back to other kinds of cells. From a biological perspective, all of these would seem to be required for an organism to transform from one form to another. So we know something about the parts involved, but not their relative effects and how they’re triggered in the right order.
This is a wonderful study that also leads to many more questions than it answers. How did this jellyfish acquire immortality and why is immortality so uncommon in biology? What are the minimal genes from the “immortal jellyfish” that a mortal kind of jellyfish would need to be able to reserve back to younger forms? And conversely, what would happen if these genes were gone from the “immortal jellyfish”? Would they lose the ability to regenerate over and over?
I think an interesting follow-experiment to the ones that the researchers have done will be to see how jellyfish that have gone through multiple rounds of regeneration from adult to juvenile forms vary over generations. They may appear to be identical, but on the genetic level we would expect to see differences in their DNA sequences over time. After all, change is a constant in biology.

What else I’ve read

"Lanternfish, the Earth’s most abundant vertebrates, may be the ultimate food source. But will catching them ruin the climate?" Super story.
A disease-causing fungus was found on stored apples in India, but not on fresh ones. Fungal “strains from apples had closely related strains from other sources in India, including from patients, hospitals, and marine environments…”
Cancer cells hide inside each other when the immune system attacks. Fascinating stuff.
60 gut microbes evolved alongside humans since we first left Africa. Great piece.
Ancestors of whales once walked on land. This is the story of how they made it to the sea.
A single gene (and amino acid change) allows humans to grow more neurons than other mammals and even more than closely related Neanderthals.