37

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 ...


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) ...


23

It is hypothesized that exposure to and recovery from SARS-CoV-2 (as with other coronaviruses in humans) would generally result in short-term immunity to this strain, but we do not yet have data on this: However, according to Dr Stephen Gluckman, an infectious diseases physician at Penn Medicine and the medical director of Penn Global Medicine, who spoke to ...


11

So the direct mechanisms of norovirus immunity aren't well understood - the shortage of straightforward animal models, and the extreme difficulty in culturing the virus make mechanistic studies really rather hard. A modeling study pegged the duration of immunity at 4.1 to 8.7 years when talking about symptomatic disease, which is much higher than many of ...


8

In the US, infants are vaccinated against Hep B at birth and again a month or two later as well, because of the risk of maternal transmission. If the mother is known to be HepB positive, HBIG will also be administered. Perinatal HBV transmission can be prevented by identifying HBV-infected (i.e., hepatitis B surface antigen [HBsAg]-positive) pregnant ...


8

I commented on this question, but the OP's response prompted me to think again. Here is the graph from the document that the OP linked to: Clearly what is confusing is that the parameter referred to as 'antibody level' rises quickly, but not as a step. In terms of the x-axis, vaguely labelled as weeks, it looks as if the level of antibody continues to rise ...


7

Since another posted answer addresses HepB vaccination at least as effectively as I would have, I'll say something about first-day scheduling for BCG, which is consistent with WHO guidelines (emphasis added): In countries with a high burden of TB, a single dose of BCG vaccine should be given to all infants as soon as possible after birth. Since ...


7

As Alan Boyd says, the relatively slow rise is due to gradual uptake of the injected antibody. If you deliver the antibodies by intravenous injection or another mode that allows rapid uptake (I use intraperitoneal injection in mice) then the antibody levels peak rapidly, less than a day and probably a couple hours, and then drop off; there is no continued ...


7

No, you cannot be immune to the virus, if you haven't been in contact with it before. You are also not immune to the influenza viruses (flu), you just happened to not contract any of them. Simply speaking, being immune means that your immune system knows the specific virus and can disarm it effectively. But the immune system has to learn to recognize and ...


6

The Native Americans and smallpox First I want to note that some of the posted answers are not quite accurate. For example, smallpox ravaged the Native American population because they did not have high-affinity MHC molecules for it, which is an evolved trait. MHC molecules must be capable of binding to a large class of peptides, at least weakly, to allow ...


6

All the body does is produce a ton of cells that can recognize single antigens. Each time you encounter pathogens, some of these naïve cells contact antigen that can activate them. The activated clone replicates itself, forming effector cells that can deal with pathogens. As the infection is cleared and the population of effector cells begins to contract (...


6

Of course we can - and do - vaccinate against bacterial diseases, as these are some of the dangerous infectious diseases. Among these are: Tetanus (although here the vaccination is targeted against the toxin, not the bacterium itself) Tuberculosis Diphtheria Pertussis Haemophilus influenzae type B Cholera Typhoid Streptococcus pneumoniae Meningococcus: ...


5

The basic concept of the immune system is that it has to discriminate between self and foreign and that is only allowed to launch an immune reaction against something foreign. This is called immune tolerance which basically makes sure that all immune cells which are directed against the own organism are destroyed. If these antibodies survive, they can ...


4

As mentioned by InactionPotential, organisms and their parasites are caught in an arms race. When an organism develops a new defense, the parasites with traits that allow them to survive those defenses excel and vice versa. Parasites must balance their survival and reproduction with that of their hosts or go extinct. Over time they may become commensal/...


4

There is not really a definitive explanation for why, although it's important to note that many mammalian pathogens are not adapted to insects and vice-versa. Insects need to survive insect pathogens, and they have a number of defenses for this purpose. Animals and their pathogens co-evolve and exert selection pressures on each other. Killing the host (or ...


4

Pattern recognition receptors (PRRs) can potentially discriminate between endogenous and exogenous DNA: Microbial nucleic acids can be discriminated from self nucleic acids using various parameters, such as their sequence, their tertiary structure, their molecular modifications and their localization. In addition, mislocalized DNA and RNA can be an ...


3

tl;dr It's messy for non-human primates too. Winternitz et al. (2017) ("Patterns of MHC‐dependent mate selection in humans and nonhuman primates: a meta‐analysis", Molecular Ecology 26(2)) review studies of MHC-based mate choice in human and non-human primates. Some of the take-home messages, mostly from the abstract: [abstract] the overall effect sizes ...


3

The antibody levels go up, because you're adding more antibodies. The increase in antibodies isn't from the patient, it's from the injection of antiserum. The half life of IgG (the most common antibody) is around 20 days. IgM and IgA last for 5-8 days. Reference. So as you can see, the antibody levels increase due to the injection of antibodies into the ...


3

Everything you state is correct, except that I disagree with your statement that a "[...] virus variant itself is a protein, which is composed of peptides. A virus is typically composed of a protein capsule with genetic material on the inside. So technically, a virus is not a protein, but its outer shell is composed of proteins. Further, a protein does not ...


3

As Mowgli pointed out, a bone marrow transplant involves destroying the patient's own immune system with radiation and, essentially, replacing it with a new one from the bone marrow donor. If you did a double kidney/bone marrow transplant from Alice into Bob, then Bob's new immune system (which is the same as Alice's) would recognize the new kidney from ...


3

Yes, infection-acquired immunity is (generally speaking†) just as good as, if not better than, getting vaccinated. Remember, the whole point of a vaccine is to simulate an infection and stimulate immunity without having to suffer through the actual symptoms of a real infection, potentially getting very sick or even dying. This is regardless of whether it's a ...


3

Natural infections almost always yield a better immunity than that acquired through vaccination. However, vaccines yield a better immune-response than getting infected with influenza. That is so to say the side effects. I want to backtrack to part of your questions where you say I'm sure the immune system will "remember" that particular strain just ...


3

Yes, the cartoon is a description of immune action. Traditionally shown is first exposure being a vaccine, and the second exposure being the bad virus being destroyed. However, this cartoon is describing viral vector immunity. The first exposure is a viral vaccine. This alerts and educates the immune system about not just the intended antigen, but also the (...


2

Well, phagocytosis does not depend on opsonization, but it works better with it because the macrophages can detect the intruders more easily, but the secondary inmune response with IgG depends on the work of the APC cells, so let`s say a bacteria gets in your body for the first time, it can get phagocytated by a macrophage that will after present the parts ...


2

The question probably has a mistaken premise. Human immune systems are pretty similar to other species, at least in major structural elements. Our differences in adaptive niche have led to differences in some aspects; humans don't fare well with rotting meat, for example, while a scavenger can eat it without a problem. Many scavengers have unique ...


2

Biodiversity is the opposite of monoculture, and we know that one possible consequence of monoculture is disease transmission -- bananas being the modern poster child for monoculture leading to disease spread. The concept seems to have been most clearly presented in Schmidt, K.A. & Ostfeld, R.S. Biodiversity and the dilution effect in disease ...


2

Bone marrow transplant requires to first destroy the pre-existing immune system with chemotherapy and/or radiations. So essentially you would not have the first immune system and my guess is that yes, in theory, it would work. However, double-grafting an artificially immunocompromised patient (who clearly suffers from another severe pathology, if they need ...


2

I can't think of any pathogenic organisms that are completely resistant to the immune system. Some bacteria that cause chronic diseases (e.g. tuberculosis) are relatively resistant, and a handful of viruses (e.g. spumaviruses) are relatively invisible, but the nature of pathogen transmission would mean that completely resistant organisms would spread through ...


2

This is a proposed/tentative answer only... Statements from official public health sources could be summarized as: older people and those with certain pre-existing health conditions including compromised immune systems are more likely to be more severely affected. "More severely affected" means requiring hospitalization, suffering permanent lung damage, ...


2

The decline in serum antibody level after vaccination means the level of spike protein specific T cells declines, in another word, the virus is eliminated [1]. When the vaccine introduced a viral particle or mRNA into the cell, SARS-CoV-2-specific CDH4+ T cells recognize 2 variant spike proteins, helping B cells to secrete antibodies and activating cytotoxic ...


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