Thanks to 80,000 Hours for supporting this  SciShow video! 80,000 Hours is a nonprofit   that aims to help people have a positive  impact with their career.

You can start   planning a career that helps solve the  most pressing problems in the world at   80000hours.org/scishow. [♪ INTRO]  Developing vaccines for humans is hard enough.  Imagine trying to do so for a tiny creature with   a totally different kind of immune system. Well,  that's what scientists set out to do for the honey   bee.

Let's start with the obvious: honeybees are  a critical part of our food system - not only do   they pollinate a huge percentage of plants that we  eat, but they also make honey, which is delicious.   Unfortunately, they’re also threatened for  a lot of reasons, ranging from disease to   pesticides to just run-of-the-mill climate  change. And there’s one threat in particular   that’s a bit of a vintage throwback, with a modern  solution. The bacteria Paenibacillus larvae is a   longtime foe of the honey bees.

It causes the  American foulbrood infection, also called AFB,   which can spread quickly through honey bee hives.  Interestingly, AFB only affects larval honey bees   in their first few days of life. The bacterial  spores get fed to the larvae by nurse bees, where   they multiply inside the larvae, killing them from  the inside out. The dead larvae turn dark brown,   and the entire hive takes on a nasty smell,  giving the infection its name.

The bacterial   spores can easily spread throughout the hive,  including the honey, as well as between hives   and into the surrounding ecosystem as the bees  come and go during foraging. And these spores   can remain viable in the ecosystem for decades,  so even if you get rid of all the infected bees,   new hives brought to that same area are at risk.  There are a few available ways to treat hives   once an infection has been detected. The most  effective course of action is burning the hives   with the bees inside, and while it definitely gets  rid of the bacteria, it isn’t exactly great news   for all those bees.

A less scorched earth option  is antibiotics, which can be useful for AFB. But   in many countries, giving livestock antibiotics  to prevent disease is illegal, due to the growing   concerns over antibiotic resistance. So most of  the time, you can only give your bees antibiotics   after the infection is detected.

And when you’re  dealing with a bacteria like Paenibacillus,   that can be too little, too late. The frustrating  part is that this isn’t the first time beekeepers   and their colonies have been plagued by AFB.  Historically, it was one of the most dreaded   honey bee diseases. In the late 19th and early  20th centuries, AFB was a massive problem in   the United States, costing beekeepers thousands of  dollars in livestock loss.

Very strict state-level   inspections and hive sanitation regulations  helped to finally bring infection levels in check   in the 1920s. Unfortunately, after decades of low  infection levels, some states relaxed these rules.   That in combination with an increase in commercial  beekeeping nationwide has led to AFB infections   being on the rise again. And regulations in one  state can affect bees everywhere, since honey   bees are shipped to different locations based on  seasonality and need, which means that AFB can   be hard to prevent when regulations vary from one  state to the next.

Which is why having a vaccine   against AFB is such a great idea. This wouldn’t be  the first time we’ve immunized the animals within   our agricultural system. Vaccines are used on  lots of commercial livestock, like cows, chickens,   and even fish, to protect them against all kinds  of infections.

We’re so good at immunizing animals   that one of only two diseases that we’ve ever  eradicated was one found in cattle and their   relatives! But unfortunately, giving vaccines  to insects isn’t as simple as it is for other   animals, because of how our immune systems differ.  See, vertebrates have two kinds of immune systems.   One is called an adaptive system, which makes  antibodies to help attack a pathogen we've been   exposed to before, to try to prevent us from  getting the same infection twice. The other is   an innate system, which reacts to pathogens when  it detects them, but doesn’t make antibodies to   prevent reinfections.

And in vertebrates, vaccines  work by making the body produce those antibodies   by exposing us to a modified version of an  inactive pathogen, to teach the immune system what   to react to next time around. But insect immune  systems don’t work the same way vertebrate immune   systems do. They only have that innate immune  system.

So while they can react to pathogens,   their immune system doesn’t remember past foes.  That means honey bees can’t be vaccinated in   exactly the same way vertebrates can, since their  immune systems don’t learn, they just react. But   new research shows that insects can protect the  next generation against infection, by priming   their offspring using pieces of the pathogen  itself. It’s similar to the way breastfeeding in   humans helps pass along antibodies to the infant  through milk.

But instead of antibodies, insects   pass along the pathogen instead. Little pieces  of the pathogen cell wall get incorporated into   their fat body, which is similar to the vertebrate  liver. Then these pathogen bits get incorporated   into the developing egg, So each larva has already  been mounting an immune defense that can work   against AFB, which means that if the real-deal  shows up, they’re better prepared to fight it   off.

And it turns out that vaccinating honey bees  is a really simple process! You don’t need lots   of tiny needles or itty bitty bandaids. In fact,  you only need to give the vaccine to one bee - the   queen.

All the researchers had to do was mix the  inactivated bacteria into the queen’s dinner.   When she ate it, eggs that she laid afterward  received a little bit of the pathogen, and   got a head start on that immune response. In the  trials, queens were acquired from local breeders   and fed the vaccine for eight days in a row to  ensure successful vaccination. They then were   released into small hives to produce larvae.

The  larvae were brought to the lab and infected with   Paenibacillus before they reached 36 hours old. At  the end of the experiment, the researchers found   that vaccinating queens increased AFB survival  rate by 30-50%, when compared to larvae from   unvaccinated queens. Not only was this the first  vaccine ever developed for insects, but having   the ability to vaccinate one bee and improve the  health of the entire colony is pretty amazing.   And this vaccine’s success in lab trials paves  the way for future honey bee vaccines.

Because   AFB is really just the tip of the iceberg when it  comes to the threats facing honey bees today. This   vaccine is the first step in the right direction  for keeping them around for decades to come,   which I think is just the bees knees. While we’re out here taking first steps,   80,000 hours is here for you if you want  to take the first step toward a new job   that really makes a difference in the world.  80,000 Hours is a nonprofit that helps you find   a fulfilling job and make a positive impact with  your career.

You can start by reading their blog   posts and listening to their podcast on different  global problems and careers that help solve them.   Topics range from population ethics to information  security in artificial intelligence systems. Then,   once you’re ready to make some moves, you can  access their curated high impact career postings   for free through their job board. For a free  copy of the 80,000 hours in-depth career guide,   click the link in the description down below or  go to 80000hours.org/scishow.

While you’re there,   you can sign up for their newsletter full of  updates on their research and job opportunities.   And just to be clear, everything they provide  is always free; their only aim is to help you   find a fulfilling, impactful career. Thanks  for watching this SciShow video and thanks to   80,000 hours for supporting it! [♪ OUTRO]