How do pathologists start searching for elements which could possibly be a cure for whenever a new viral or bacterial epidemic breaches? Do they like start from A till Z of the list of elements to find out which reacts to the pathogen or something?
In: Biology
Just to clarify, are you really asking specifically about bacteria and viruses or about diseases and conditions in general? Because for the former, we have antibiotics and antivirals and can start there (note: antivirals have a ton of side effects and don’t always work because it is very hard to target a simple protein coat full of genetic material without also targeting your body).
At least according to common career definitions, pathologists don’t real do this sort of job. That’s more for microbiologists/virologists/parasitologists/etc.
And they usually start by looking at the evolutionary origin of the pathogen. Where did it come from? What other microbe did it speciate from? If we know, what did we use for that parent microbe? Etc.
For bacteria it’s easy, you have a lot of antibiotics, and we know how they work, so we know which type of bacteria they’d work on and which not. Like bacteria with a cell wall and those without. From there on it’s trial and error in a petri dish (or the human, but that’s not recommended as if it doesn’t work you get resistance).
For viruses it’s more complicated. Mostly because we don’t have any real cures for almost any viruses. We have some treatments that make things better, but I think we don’t have any true cure. So either we use the approach above and use drugs we know their mechanism and that they apply to this class of viruses, or we treat the symptoms until the body gets rid of the virus.
For other stuff like fungi and parasites I believe we follow the same concept, rely on previous evolutionary ancestors that we do have a treatment for.
And if in any of these cases we don’t know what to use there are always general drugs for the specific pathogen that we can try.
Antibiotics and antivirals can be classed based on what’s called their “mechanism of action” or MoA. This just refers to the way in which they kill the bacteria or stop the virus. Nowadays, there’s not really completely “new” diseases. Most are just variations of what we have already observed in nature. But if there is something new, or at least something we’re not used to treating, scientists will study the pathogen intensely and determine which mechanisms of action would be effective. They may certainly start with broad-spectrum antibiotics and work their way towards optimizing a treatment, but they usually have a pretty good guess as to what may work before more detailed biochemistry experiments begin. For example, determining the components of the bacteria’s outer layers can rule out many antibiotics as possible treatments.
The biggest obstacle can be successfully “culturing” or growing enough of the pathogen to study it. Such was the case for the Legionella bacteria, responsible for the Legionnaire’s disease (a pneumonia-like disease) outbreaks in the 70’s. It was previously unknown before this outbreak, and the discovery itself took a long time because it was difficult to culture. But many antibiotics used for general bacterial respiratory tract infections are helpful for Legionella infections, so in a scenario where a pathogen is new, patients could receive those antibiotics while possibilities of better treatments could be evaluated.
Viruses are a bit trickier. They like to use our own cells’ machinery to reproduce and make proteins, so it can be difficult to target a virus without targeting our own cells unless we can hone in on something specific to the virus. Additionally, much of their dirty work takes place inside our cells, so it is harder to reach them. But it is certainly possible. The development of antivirals requires intense biochemical study. Some of the individual characteristics of viruses are harder to figure out compared to those of bacteria. It important to figure out what type of virus it is. In modern times, this can be accomplished easily by sequencing the unique DNA or RNA of the virus. This just means looking at the “letters” of that DNA or RNA. Sequencing is useful for bacteria too, it’s just that bacteria have lots of other characteristics to look at as well. But back to viruses, sequencing a virus can help determine what type of virus it is, which will also tell scientists what type of machinery it likes to use. They can then work on finding specific and precise targets for antiviral drugs.
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