Why don’t they just take a few soil samples (which contain so many different bacteria), kill them (with say radiation) and make a much broader vaccine?
I realize virus vaccines may be hard, but what is the issue with bacteria?
There are a bunch of things wrong with that idea, but start with: if the bacteria in soil were particularly likely to make you sick, you’d be sick all the time. We also don’t generally vaccinate against bacterial infections, since they’re generally short-lived, relatively harmless compared to their viral cousins, and because they can usually be easily treated with antibiotics (well, and because the mechanism is different, but I’ll let the doctors weigh in on that.)
Killing all the bacteria in your body, even if it were possible, would be an extremely bad idea. Your digestive system is full of bacteria, and it’s supposed to be; presuming that you’ve got the right ones in there, they help your digestion, reduce inflammation, and discourage bacteria you don’t want; and may well have additional beneficial effects we don’t understand yet.
And if you could make a vaccine just by killing the organism and using the remains, we’d have had one for AIDS a long time ago, no? Making functional vaccines must be more complicated than that.
There are at leasteight different strains of E. coli bacteria proven to cause illness in humans. That’s in two particular types of that bacteria. There are nine general types of* E. coli*. Which one are we looking for in which sample of dirt?
In addition to technical difficulties involved in cramming so many bacterial antigens into a single vaccine and unwanted/unforeseen effects of “protecting” against both good and bad bacteria, there are hazards to exposing humans to a “broad spectrum” of antigens.
As an example, the “whole cell” vaccine against just one pathogen (the agent of pertussis) produced a very effective vaccine but one which was deemed to have an unacceptably high rate of side effects.*
A vaccine containing antigens of perhaps thousands of bacteria might have a few unpleasant consequences.
*the replacement vaccine has been safer but not nearly as effective.
Even some of the bacteria that can make you sick are essential to your health. You’d get very sick indeed without any E. coli, for instance. As its name suggests, it’s usually found in the colon, and it has an important job to do there. It only makes you sick when it gets out of the colon and into other parts of the body.
I am confused – why would the immune system react in the gut? doesn’t it work for only stuff in the bloodstream?
I am under the impression that bacteria in the gut would get eliminated upon entering the bloodstream.
There are a lot of different strains of E coli, it’s not all one thing. Some of them are very much beneficial. Many of them are neutral to humans. A very few of them are dangerous and can be deadly – even in your gut.
Your gut ought to be full of E coli or it won’t work right. But it should not contain E coli 0157 or you are likely to get very sick.
The intestines have the largest mass of lymphoid tissue in the whole body. The gut is as much about the immune system as it is about digesting food.
GALT (gut-associated lymphoid tissue) from Wikipedia:
Disagree here, pneumonia, diphtheria, tetanus, meningococcal septicemia, epiglottitis, cholera, typhoid, and anthrax are all bacterial infections well worth vaccinating against and commonly are.
humpf, forgot whooping cough.
I heard the gut has a strong immune activity, but I figured it activates once something penetrates the first barrier. Are you saying there are white cells outside the bloodstream, walking on the lining wall of the gut?
Why then don’t we acquire immunity to every bacteria that finds its way into the gut?
Again, most of them are beneficials or neutrals.
And immunity is a continuing arms race. We’re evolving immunity, the pathogens are evolving to evade it.