Briefly, a lot of our vaccines and antibiotics need to be refrigerated, if not frozen, for them to maintain their usefulness. This makes it problematic to get vaccines and antibiotics to places that need them, but lack proper refrigeration (or electricity, for that matter)-- Its called the Cold Chain.
Some folks at Tufts think they have figured out a way to store some vaccines and antibiotics, which would obviate the need for the Cold Chain:
WARNING: I am not a structure person! But from my understanding, they mixed silk proteins with various vaccines and antibiotics, and allowed the mixture to form a dried film (frequently vaccines are stored in a dried form, even the live attenuated ones).
What they found:
Regular ol solutions of tetracycline kept at 4 C was fine (lost a little bit of potency), but when it was stored at 25 (room temp) or 37 (body temp) it degraded over the course of four weeks, and tetracycline stored at 60 (HOT!) was functionally useless.
Tetracycline stored as these silk films, however, were better than fine. 4 C solutions were at about 90% potency after four weeks, where the silk films, at all temperatures (even 60 C!!) were at ~100% potency after four weeks.
They carried this experiment out further-- the tetracycline films (and they also had a powder version) stored at 60 C were stable for at least four months. FOUR MONTHS!! Tetracycline that, when stored properly, should have started to degrade by four weeks, was still fine and useable stored at 60 C for FOUR MONTHS!
- MMR vaccine
The regular MMR vaccine is made up of freeze-dried live measles, mumps, and rubella viruses. The researchers carried the vaccines out for 24 weeks,and when stored at 4 C, its fairly happy. It is less happy at 25 C, and functionally useless when stored at 37 or 45 C for very long.
When MMR was stored a silk film, things change dramatically. As a silk film, the MMR vaccine was stable for 24 weeks, that is SIX MONTHS, at 45 C. They got infectious measles, mumps, and rubella viruses off of silk films stored at 45 C for six freaking months (they also tried a powdered form, and it worked okay, but not as well as the film).
This worked, hypothetically, because the silk proteins created a network that surrounded and protected the vaccine/antibiotics from water (damaging) and diffusion/motion (damaging). The silk network also prevented the viruses from clumping together in aggregates-- clumps that would be non-infectious, which defeats the point of a live attenuated vaccine (infection).
But, like I said, Im not a structure person. Im not an engineering person. I understand the concept of what these authors describe, but I cannot critique the science myself. Unfortunately, with my previous concerns about PNAS and their publishing policies, I also cant be certain that this paper was peer reviewed by scientists who could critique this science either. So, I just dont know whether (if implementable) this new approach is mind-blowingly revolutionary... or total BS. :-/
I'm surprised this was published at all, these films should make a fantastic distribution agent for biological warfare agents.
You accidentally added your uni's library's webproxy to the PNAS web address. The correct addy for us non-Uoklahoma types is:
You can usually guess if PNAS articles were reviewed, based on the submission and acception dates. In this case, they're 3 months apart - unlikely to have undergone significant review.
Pretty effin' cool there if (as you cautioned) it works as advertised.
They should totally teach spiders to do this.
-- exactly! They could genetically modify spiders to hold on to the vaccine internally, then spray it out as vaccine-containing spider silk.
... make that radioactive spider silk...
This article was edited under PNAS' "Direct Submission" protocol which is on the level of what expects from a standard peer-reviewed article.
Why do all their tetracycline samples gain activity between 6 and 9 months?
re "I also cant be certain that this paper was peer reviewed", PNAS state what route their papers take, e.g. "This article is a PNAS Direct Submission" in this case.
I'm sure the Gates Foundation will jump on this, as it seems to be right up their alley. We'll find out if it's real soon enough.
Here's something similar that came out two and a half years ago using a sugar film as the substrate (if substrate is even the right word). Have no idea whether the findings held up and/or whether they have been implemented since then.
Vaccines in sugar film could save millions