In humans, our antibodies are a mix of two pairs of proteins, heavy and light, that are wrapped around each other. Llamas however (like a few other animals) have antibodies only with heavy chains. That's why scientists believe they're the key to improving our immunity.
Llama antibodies are smaller chains, meaning they can fit into spaces between molecules that our antibodies can't. That why researchers at the Scripps Institute have been studying how to apply them to improve flu protection.
The influenza virus comes in four types. Influenza A and B (unlike C and D) are what cause seasonal flu epidemics, but it's influenza A that causes pandemics. Influenza A is further divided into subtypes based on two proteins; hemagglutinin (H) and neuraminidase (N). There are 18 H subtypes and 11 N subtypes in total. That's how bird flu and swine get names like H5N1 and H1N1 respectively.
Right now, flu vaccines tackle the hemagglutinin protein, which frequently changes itself. That's why flu shots aren't a permanent vaccine like those for smallpox, but require to be administered every year. These flu shots allow our antibodies to attach to and counter influenza strains in circulation at the time. Scientists have previously developed antibodies that counter all kinds of hemagglutinin, but they end up being weak against influenza B, and aren't very long-lasting.
So Scripps researchers have experimented with llamas, immunizing them with a flu vaccine and extra H molecules, then isolating the four antibodies they made in response. Two of those were against influenza A, and two against type B.
Each of those antibodies were effective against a separate group of flu viruses, but none of them overlapped. The scientists then combined different parts of the llama antibodies (called nanobodies) with a human antibody base. In testing, these were able to neutralize flu strains that none of the components were able to alone, including 60 different flu viruses in mice they were tested on. Not just with an injection, the new vaccine was also able to protect the mice from flu when fed intranasally a full month before infection.
"If the above preclinical findings translate to humans, an annual intranasal administration may provide passive protection for the entire influenza season and would be of particular benefit to the elderly and other high-risk groups," the study states. Basically, that means people would be able to reliably stave off a majority of flu infections for the whole year with a single dose of nasal drops at the start of the year.
Of course, it's still all up in the air, at least until the scientists can complete human trials. But aside from just the flu, they believe the technique can also be used to protect against other rapidly mutating pathogens like Hepatitis C and even HIV.