Today in class, there was a discussion going on about what part of pathogens(which can act as an antigen) can be used to make vaccines. There was this point where our teacher said that bacterial exotoxins can be used for making vaccines.

My questions are-

  1. Can bacterial endotoxins be used in making of vaccines?
  2. If not, then why is it so? What are the problems we face ?

There are several papers that use alkaline hydrolysis to delipidate or "detoxify" the endotoxin for use as a vaccine (1, 2, 3). The point of many of these papers is to develop a detoxified LPS (dLPS) vaccine to protect against sepsis in the pathogenesis and treatment of gram-negative infections. The detoxification is important, as the lipid-A portion of the LPS contributes significantly to sepsis. In this case you would be targeting the O-antigen or core oligosaccharide.

So one of the problems that I can see is that there are many bacterial serotypes, comprised of many different O- and core groups. I'm not aware of any vaccines with that sort of breadth. Issue two is you get an infection and you need to administer these vaccines quite fast, if not prophylactically, as adaptive immunity takes a number of days to come to speed.

It's also not clear to me whether a prophylactic vaccine to E. coli is useful to the populace at large, epidemiologically (just as an example).

The field also seems to lack clinical data on tolerability and efficacy, which is what I'd be more interested in, e.g. is it safe for humans and does it work?

  • $\begingroup$ So they are just under trial and aren't used as prophylaxis because 1) of the differences in core groups of the LPS of the same bacterial species. So, speaking prophylactically , the vaccine will be effective against only one strain of that bacterial species and not as whole. 2) we still don't have any idea on the efficiency and safety of these vaccines.Am i getting that correct? Furthur, can you provide a link to the structure of endotoxin(LPS) . I really don't have much idea about the A-portion and O- part you talked about but I'm interested in finding out. $\endgroup$ – anamika Singh Nov 4 '17 at 20:25
  • 1
    $\begingroup$ @anamikaSingh You have this idea of multivalent vaccines. For example, the conventional flu vaccine is trivalent, consisting of live attenuated bacteria from the three groups predicted to cause the most sickness that year. The strains the following year may differ due to mutation (aka antigenic drift). So it's not to say that you can't have multivalent vaccines, for example, but it's costly and laborious to produce a product against so many different serotypes. And yes, the other issue is that they don't seem to be well-tested clinically. $\endgroup$ – CKM Nov 5 '17 at 6:36
  • $\begingroup$ This is a fair structural representation: html.scirp.org/file/5-2270721x6.png. $\endgroup$ – CKM Nov 5 '17 at 6:37

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