New here and this is my first thread. The last couple times I talked to doctor friends (many years ago) about viruses is: you can’t make a vaccine for viruses the same way you do with bacteria. Also you can’t really cure a viral infection besides giving supportive medicine.
Are these (still) correct? A vaccine as I understand it is a shot of a pathogen, weakened with alcohol, that will allow your body to produce antibodies to fight the full-powered pathogen that might infect you. Does that work with viruses also?
Normally vaccine refers to something that fights viruses. You can vaccinate against some bacteria, but it’s more of an anti-viral tool.
A virus is small enough that an antibody can either “jam” it (by covering its receptors that enable it to enter a cell) or cause them to stick together in bunches, letting white blood cells eat a bunch of them at once. Antibodies generally have a lesser effect against bacteria, although they act by essentially attracting white blood cells toward them. By contrast, bacteria are typically vulnerable to heat, or to simply being eaten (individually or in chains, even without the benefit of antibodies) by white blood cells.
A retrovirus literally cuts out part of the DNA of the target cell and inserts itself there, then spawns copies of itself (many of these copies are missing bits or have added bits of host DNA, so they tend to mutate fast). Once it’s inside the cell, what could you possibly do to stop it? Sometimes the immune system can be primed to destroy these cells. (Many viruses “steal” part of the cell membrane, but need their receptors, which are produced on that membrane. The immune system can sometimes recognize that and destroy the cell. The same system destroys some cancer cells.)
Anything that damages DNA can cause cancer, such as a virus cutting out parts of the cell’s DNA and otherwise mucking about with it. Some viruses are notorious for causing cancers, but most retroviruses are not.
Other viruses just enter the cell (often by directly injecting their DNA or RNA into the cell) and hijacking their protein-synthesis mechanism. Again, they’re already inside the cell. About the only thing that would stop the virus is killing that cell. Crucially, anything that destroys these cells needs to only destroy these cells. I believe viral infections tend to end because the virus takes over too much machinery and kills the cell. Some viruses can become dormant in the victim cell’s DNA and emerge decades later.
Interferon can sometimes interfere with virus production or signal the rest of the immune system.
That’s a lot for me to chew on. But your first sentence “Normally vaccine refers to something that fights viruses” is a surprise. Isn’t mainly for bacterial infections?
Not totally accurate. I’m not a doctor, but from what I know it depends on the virus, but there are drugs on the market that work because they block proteins the virus needs to replicate and grow. Tamiflu blocks a protein the flu virus needs to reproduce, there are a wide range of drugs that block proteins the HIV virus needs. There are also drugs that block the receptors that certain viruses need to enter your cells, etc.
There are also drugs that can strengthen your immune system so it can fight a viral infection better. Interferon is a major one, but also drugs like cimetidine have been used to make people’s immune systems stronger so they can fight an infection.
The two sorts of medicine also differ in when you give them. A vaccine is given (hopefully) before you’re infected, to prevent you from ever getting sick in the first place, but isn’t much use for a disease you already have. An antibiotic will treat a disease you already have, but won’t do anything to prevent future infections.
This is also wrong. Vaccines just deliver a specific protein that is expressed as part of the infective agent (bacteria or virus) - this trains elements of the immune system to be prepared for that particular protein, and to destroy it when it appears. This has the effect of killing the virus when you are exposed to it.
It also means that you cannot get infected with the disease when you get a vaccine - because there is no viral DNA in the vaccine - it’s just a protein. You may just feel unwell for a period of time due to your immune response.
Modern antivirals interfere with viral replication, usually by providing something that is similar to (but not quite) like something that it requires during viral replication. Often these are nucleoside analogs - they look like nucleic acids (the elements of DNA/RNA) but act to terminate DNA/RNA polymerization when included by transcription. This preferentially impacts fast-replicating viral DNA polymerase/reverse transcriptase.
Yeah - Varicella (chickenpox) vaccine anD MMR is still an attenuated virus - basically they force-engineered a non-infective version of the varicella virus. I thought that it had been supplanted by an engineered protein, but I’ll admit to being incorrect.
This is the first I’ve ever heard that these vaccines don’t prevent the infection but merely somehow make you immune to the “effects” of the infection. That doesn’t make any sense to me at all.
By the way, do y’all know how vaccines came to be called vaccines? I learned this just yesterday while poking around on Wikipedia reading about vaccines, smallpox, and cowpox. It originally referred just to smallpox, but the word was later generalized to mean preventative inoculation against other diseases too.
Yeah, just having bacteria inside of you isn’t in itself a problem. In fact, a healthy body contains more bacteria cells than human cells. It’s only a problem if the bacteria make it a problem… such as by producing toxins.
Just to make it perfectly clear. Until anti-AIDS drugs were developed, the mantra was that you vaccinate against viral diseases and could treat bacterial diseases with medication but not the reverse. There were no antiviral medications and no anti-bacterial vaccinations. Things have changed somewhat in the past 30 years.
We were working on a vaccine for RSV. The virus only lived in primates. Primates are expensive and many organizations are against experimenting with them.
Fortunately, for us, the Cotton Rat could support the virus. We had bred the rat to make clones of them. And was able to experiment on them to test hypothesis’. Because the market to develop a vaccine was small, the big drug companies didn’t want to play.
A vaccine was discovered. But someone beat us to the punch.