Hot answers tagged

40

The phrase "Breast is best" is a hotly debated one (source: The Guardian and personal communications with many folks). The reason why we don't want to feed infants cow's milk is, however, anything but debated, because Cow's milk does not provide enough: Vitamin E Iron Essential fatty acids And because it contains too much: Protein Sodium Potassium (...


24

It is possible for viruses to live in mutualistic relationships with their hosts, these associations are often overlooked due to the devastating effect that many viruses can have. To give an example in humans, when HIV-1-infected patients are also infected with hepatitis G virus, progression to AIDS is slowed significantly (Heringlake et al., 1998; Tillmann ...


23

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 ...


21

Unlike erythrocytes that have a very rigid shape and almost cannot change their size (hence the size distribution is indicative and can be used for diagnostic purposes in medicine), lymphocytes can change their size in a wider range, this is why you see the numbers 6-9 and 10-15 μm. And they indeed cluster into several different groups: so-called "large ...


17

Vaccines work by introducing an attenuated strain of the pathogen (or alternatively the antigens that are normally present on the pathogens surface) into the body, whereupon the body mounts an immune response. As this will (hopefully) be the first time that the body has encountered the antigens on the pseudo-pathogen's surface, the response is called the ...


17

According to the Wikipedia entry for the ABO blood group system: Anti-A antibodies are hypothesized to originate from immune response towards influenza virus, whose epitopes are similar enough to the α-D-N-galactosamine on the A glycoprotein to be able to elicit a cross-reaction. Anti-B antibodies are hypothesized to originate from antibodies produced ...


16

Personal comfort is the primary answer. Quite a bit of research has gone into fevers, and the current consensus is that Fevers less than 105F (40.5C) shouldn't necessarily be treated. The primary reason the body raises its temperature (via the Hypothalamus in this case) is that bacteria and viruses tend to optimally thrive at 98.6F, which is also your body'...


16

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 ...


16

So while some kind of a biological database might have been an evolutionary option, the way we evolved is different from this. Rather than 'planning' what diseases could be recognized in the environment and recording this, our bone marrow constantly pumps out naive B and T cells that have a randomized receptor on them. The effect of this is that every new B ...


15

The goal of the vaccine is to provoke an immune response, therefore some degree of inflammation is expected in order for the vaccine to work. As swbarnes2 says, vaccines contain adjuvants, pro-inflammatory molecules that produces local inflammation and recruits immune cells to the site of the inoculation. Since you get the shot intramuscularily, ...


15

I think no one can really deny the existence of HIV or AIDS, just a search on google scholar will show >1,500,000 hits for each of those terms, and ask (hopefully any) doctor and they will say it does, though AIDS denialists do debate whether HIV causes AIDS. This paper explains the process of HIV causing AIDS. Further, AIDS denialists have not offered up ...


15

Doctors would recommend the use of barrier protection for couples where both partners are HIV+ because the virus can mutate. Mutated forms of the virus can become resistant to Highly Active Antiretroviral Therapy (HAART) treatments, rendering them ineffective. The use of barrier protection reduces the risk that a resistant mutant strain of HIV is ...


15

With AIDS, the whole immune system is not non-functional. The condition results in a severe drop in CD4+ T-cells, which is what primarily predisposes AIDS patients to secondary infections. Fever can be an immune response to infection, but it is not directly affected by the loss of CD4+ T-cells. Rather, fever occurs due to a complex cascade of events ...


14

It is not only the immune system that prevents us from getting ill. Worrying much in my opinion won't make you catch a cold; rather, you can get problems with your cardiovascular system (arrhythmias, hypertension, angina pectoris) or limbic system (panic attacks, sweating attacks etc.). The connections are many; here are some possible ones: There are many ...


14

In the graph above the darker blue line refers to the antibodies the baby receives from the mother in utero, as you mentioned in your question. As you can see, the red line indicates that babies begin to produce low levels of their own antibodies between 3 and 6 months before birth. However, these are IgM antibodies, immature 'rough draft' versions. ...


13

MBQ and Rory M have already given decent answers on the "hows" of how the vaccine memory is formed. Now, for some twists: There are three (general) types of vaccine, all of which are meant to make your body "think" its being infected and provoke an immune response, while at the same time not causing active infection. They are: Live attenuated. These ...


13

Most information here can be found broadly in Cellular and Molecular Immunology, 8th Ed. Here's how the flu vaccine works: Scientists forecast months in advance which strains they think stand to cause the most problems. The vaccine is often trivalent, protecting against three different strains on flu: Two influenza A and one influenza B. You can read about ...


12

Duration of efficacy is typically determined by tracking the antibody titers of a cohort of subjects who have gotten the vaccine, and estimating based on the trajectory of those titers where they will eventually cross the threshold to the point where the vaccine no longer confers immune resistance. These estimates do get revised and estimated as time goes ...


12

Alright, having read the citation linked, and doing a little poking of my own, here's my approach at an answer: Some human herpes virus infections may compete with HIV infection. Essentially, some strains (not the ones you normally think of) infect CD4 cells - the same cells targeted by HIV. These strains down regulate transcription in CD4 cells, which in ...


12

I think the current answer to this for bacterial infections is quorum sensing. Quorum sensing is a signalling pathway in bacteria which senses a molecule that the bacteria themselves secrete. When the concentration of the quorum signal reaches a certain level, the bacteria interpret this as their population density reaching some threshhold. Bacteria are ...


12

The combination of these two reports from the CDC give information about the comparative prevalence of flu infection in the winter (September '12- May '13) and summer (May '13 - September '13). I'm going to assume that 2012-2013 was a fairly representative year as far as the level of detail of "do we get sick more in the winter" goes. Particularly striking ...


12

The reasons why HIV is "incurable" (a misnomer) are legion: HIV is a retrovirus, which means it inserts its own genome into the host cell's genome. You must therefore kill each and every infected cell to rid the body of the virus. HIV is a lentivirus, which means it has a long incubation period, so it can "lay low" before symptoms are readily detected. ...


11

They appear sick because they are sick, but with other, opportunistic infections. The "immune deficiency" part of AIDS means that the immune system is not functioning normally and, thus, is unable to protect them. Typical illnesses that are more found more frequently in AIDS patients are pneumocystis pneumonia and Kaposi's sarcoma.


11

Nothing. Rhesus incompatibility results when people who are Rh- develop antibodies against Rh+ blood after exposure. People with Rh+ blood do not show any such reaction to Rh- blood. In a way, it's comparable to blood types in that regard. People with the blood group O can develop antibodies against type (for example) B blood. People with type B don't ...


10

I'm not sure if I should be posting this as an answer, but I think a very approachable and accurate account of the history of HIV can be found from Dinis de Sousa et al.. I agree with what has been posted above. On the theory that a picture is worth a thousands words, you might also introduce skeptics to the cryo-electron microscopy images of the virus (...


10

These so called virgin B-cells (becase they never had contact with their antigen) which are present in your body only have random B-cell receptors (when secreted, these are the antibodies), mostly of a relatively low binding affinity. These B-cells undergo division, re-arrangement and somatic hypermutation of the B-cell receptor and clonal selection. Only ...


9

Infectious agents like bacteria, viruses, fungi, etc., don't know when to "attack" or produce pathogenic substances, they just do it under their preferred conditions, and your body's immune system either succeeds in fighting them off immediately, or it doesn't and you get sick. Your body is constantly confronting and clearing potentially dangerous ...


8

As I'm lucky enough to have access to that article, I'm going to extract whatever I can find to answer your question. To begin with, innate immunity must have evolved first - we can see it at almost all stages of evolution. According to Cooper & Herrin, ever since aerobic respiration gave rise to multicellular organisms which in turn needed protection ...


8

Small molecules do not have antigenic properties but they can elicit immune response by binding to a "carrier" protein. The small molecule is called a Hapten. An epitope forms at the protein-hapten binding interface. Nickel acts like a hapten and elicits immune response by binding to proteins like transferrin, albumin etc. Other metals also cause ...


8

No, many unicellular organisms are not bacteria. Examples include (but certainly not limited to); some fungi, chlorella algae, and archaea. Bacteria are one of three domains in the classification of life. You can find more about the bacteria domain at the wikipedia page (It's a long and complex history which is hard to summarise here) and about the domains ...



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