107

At the moment, there is very little scientific literature about this, but I found two papers that address the problem and are fairly easy to understand. You can find them in the references. Reference 1 is probably the most interesting and is the basis for this answer. Edit: It is also interesting to read reference 2 on the origin of SARS-CoV-2; the article ...


79

Do they exist? Yes What are they called? Marilyn Roossinck calls them viral mutualistic symbiotes. She has an excellent review here. What are some examples? My personal favorite is GB-Virus C, or Hepatitis G, which appears to slow the progression of HIV using a number of different mechanisms: Box 1. Summary of the effects of GBV-C infection in HIV-...


72

If this is a topic that really interests you, I'd suggest searching for papers/reviews/opinions written by Didier Raoult. Raoult is one of the original discoverers of the massive Mimivirus and his work will lead you to some truly fascinating discussions that I couldn't hope to reproduce here. The main argument for why viruses aren't living is basically ...


70

You must tell facts from fiction; viruses need living cells to replicate because they do not have the molecular machinery at hand to generate energy and construct building blocks essential to life. So no, viruses cannot bring back the dead or revitalize dead cells. One thing that comes close to it are the so-called zombie ants. These ants have been ...


59

Yes, this helps as well with other infectious diseases. A good example is the flu, which season was measurably shorter this year than in other years on record. See the figure from the reference 1 for comparision: Reference 2 shows that this is also true for other respiratory diseases (figure 2): This shows very well that the isolation measures and the ...


55

Many important viruses are coated with a lipid envelope and rely on this to enter the host cell. This envelope is fragile - it's similar to a soap bubble - and it can be disrupted in many ways. Lipids will oxidize in air over time and this will degrade their ability to maintain an envelope. Surfactants such as soap or solvents such as alcohol will disrupt an ...


54

It doesn't. Viruses don't "know" anything. Mutations occur at random. Most of them don't do anything, or have a slight negative effect on the ability of the virus to infect and reproduce. However, there are billions and billions of viruses. Once in a while a random mutation will offer a significant advantage like immunity to an anti-viral drug. The viruses ...


54

The CDC has made available online its nCoV test kit. Briefly,the kit contains primers and probes for real-time reverse-transcriptase PCR, as well as instructions for appropriate use and (critically) controls and guidelines to avoid false positives and negatives. Kits from different countries may use slightly different primers and probes, though since they ...


49

Infections spread in a population when the number of new infections caused by an infected person is greater than or equal to 1. If each infected person spreads the virus to less than 1 person, eventually no one will be infected, without a need for any sort of cure. Of course, the longer a deadly infectious disease spreads in a population, the more people ...


47

Can someone die of the common cold? No. The common cold is a clinical syndrome restricted to upper respiratory tract involvement. By clinical syndrome, I mean it is the constellation of symptoms (rather than the consequence of a specific pathogen). As you mention, these symptoms are the result of the immune response, rather than tissue damage or ...


43

This question makes a number of incorrect assumptions and I don't have time to correct them. The short answer is that the virus has mutated probably hundreds of times since it entered humans in late 2019. The lower figure on the NextStrain.org ncov page, "Diversity", shows the known mutations that have been identified so far. As I look at it now, there are ...


42

This is a poly(A) tail, which is a feature found in the majority of eukaryotic RNAs (especially mRNA) and is also not uncommon in RNA viruses (which essentially mimic endogenous mRNA for their own replication). As with mRNA, this poly(A) tail in coronaviruses is bound by poly(A) binding protein in the cytoplasm [1], which is involved in translation ...


40

In addition to Chris' answer above, the effect is even more pronounced in Southern Hemisphere countries where flu season started during the pandemic. The New Zealand lockdown and health response dramatically lowered the prevalence of reported flu-like symptoms. Reference: Flu Tracking reports - New Zealand – week ending 31-May-2020


36

Long lasting immunity is obtained by means of the adaptive immune system, and mainly involves the development of antibodies that identify specific parts (epitopes) of the pathogen's proteins. Common cold is typically caused by a type of virus called rhinovirus. Viruses have very high mutation rates, which alter the sequence of the virus proteins, modifying ...


36

Do physicians/biologists not know all the different types of viruses out there? No, Biologists don't know all the viruses that exist out there. There's a lot! We do know many of the ones infecting humans, though, especially the ones leading to the most common diseases. The fact that the doctor didn't know what type of virus she has bothers me. ...


36

So I think this is a more conversational kind of question. I will address some misconceptions you have, and I will try to keep it brief, considering the nature and depth of your question. One could comment on the question very deeply, so I'll stick to addressing some misconceptions. Can I tell whether my sandwich is contaminated for example? Usually you ...


36

As you could imagine, a systematic cataloguing of bacterial or viral flavor profiles would violate a number of biosafety protocols. However, in a laboratory setting, different bacteria definitely have distinct odors. In some cases, the odor is even included in guidelines for laboratory identification of an organism. However, that odor is typically not a ...


35

To my knowledge, yes. A partial list of recently emerged/emerging viral diseases (I certainly could have missed some), with probable reservoir hosts: Chikungunya* (birds, rodents) coronaviruses (SARS [bats], MERS [camels], COVID-19 [?? bats ?? pangolins ??]) Ebola and other filoviruses (Marburg): (bats?) Hendra, Nipah (bats) Ross river virus* (various ...


33

HIV was identified as an infectious disease through classical epidemiology, and the virus was identified through classical virology. I won't get into the epidemiology, but briefly it went pretty much as you'd expect -- a cluster of symptoms were identified, patient characteristics were analyzed, the contagious nature of the symptoms were recognized, all ...


32

Mainly cost/benefit analysis. Using vaccines has a cost, both in dollars and in risk. That cost may be very low (cheap safe vaccines, like measles vaccine), or may be relatively high (smallpox vaccine is relatively risky, with around a 1 in 300,000 chance of moderate to severe side effects); but there is always some cost. Vaccines may not have any ...


28

Ultraviolet (UV) light emitted from the sun has enough energy to break chemical bonds in DNA and RNA. Some frequencies of UV light can cause damage in the DNA in skin cells that can lead to replication and expression errors, which lead to cancer (melanoma). Similarly, UV can break up and inactivate the genomic payload of a virus: Sunlight or, more ...


25

It is only a question of definition. You can set the boundaries between living things and not living things anywhere. Some philosophers have argued that using a clear boundary between living and non-living things is not such a good solution. In nature, there would rather be a continuum from a stone to a bacteria. It is true that in thinking of viruses such ...


25

Another good virus would be a Bacteriophage, a virus that infects and kills illness-causing bacteria. From Wiki: A bacteriophage also known informally as a phage, is a virus that infects and replicates within Bacteria and Archaea. The term was derived from "bacteria" and the Greek φαγεῖν (phagein), "to devour". Bacteriophages are ...


25

How long should I wait before handling the parcel to avoid contracting the virus? If you use gloves, or don't touch your face and just wash your hands after opening, you don't have to wait at all. If you don't use gloves or want to pick your nose, rub your eyes, or fiddle with your beard while opening the package, wait 24 hours if the package is nonporous, ...


25

This virology site has a post about a 2017 paper about membrane-vesicled plasmids that act in ways that are theorized to be precursors to how viruses work: It is likely that the plasmid-containing membrane vesicles are precursors of what we know today as virus particles. It is thought that viruses originated from selfish genetic elements such as plasmids ...


24

The flu virus changes rapidly so that the current vaccine doesn't work against the new strains. The way vaccines work is that they teach our immune system what to look out for. The vaccine contains bits of the virus but in a form that can't cause a proper infection, the body learns what to look for and next time before the virus can really get going the ...


24

First, I want to note that ddiez has a good answer, but I thought this was good question to have a more expanded answer on immunology and pathogenesis. The First thing we need to establish what is a "cold". The most common cold is rhinovirus (HRV), but the second place holder is a little harder to define. For example, respiratory syncytial virus (RSV) ...


24

It's a cost/benefit situation. Yes they could have taken samples, processed them, teased out the virus, and eventually identified exactly what virus (sort of*) that your girlfriend had by its gene sequence. But do you want to pay 10k-100k per virus to find that out, or just pay $20-100 and take some fluids and be fine. I say sort of because viruses tend ...


24

There are actually 3+ types of test kits widely used to diagnose diseases caused by viruses. We can check for the nucleic acid of the virus, the antigen of the virus that would cause an immune response or the antibody produced during the immune response of the patient. Since we've already got the whole sequence of the nCoV, the test kits normally used this ...


24

Hepatitis D emerged in the past 100 years, without being a zoonosis Hepatitis D is a virus which is able to replicate only in the presence of a hepatitis B co-infection. It causes the same symptoms as the hepatitis B virus, but with greater severity and lethality. In developed countries, it is rare except among intravenous drug users. It was discovered ...


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