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 ...


19

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 ...


15

It's didn't disappear. It's still around today, over 100 years later. The 1918 influenza virus is the parent virus for all the human seasonal influenza viruses that are around today, as well as for most of the swine influenza viruses out there. In fact, the presently circulating H1N1 viruses in humans are close enough to the 1918 virus that they probably ...


9

“Swine flu” is an obsolete name. The official name for the virus that was briefly called “swine flu” is “H1N1pdm09”. H1N1pdm09 has a mortality rate of around 0.01-0.1%. That’s roughly 10- to 20-fold lower than COVID-19. Its R0 was estimated at between 1 and 2, which is roughly half the estimates for SARS-CoV-2 (the virus responsible for COVID-19]. A ...


9

Contrary to many beliefs our immune system needs no "training". It is permanently active and confronted with dozens to hundreds of antigens in our food, from dust we inhale and so on. This all happens to protect our body from the environment and the immune system is pretty efficient with that and certainly it is not getting lazy. By vaccinating against a ...


7

Perhaps just eight to 12 hours. Both influenza A and B viruses survived for 24-48 hr on hard, nonporous surfaces such as stainless steel and plastic but survived for less than 8-12 hr on cloth, paper, and tissues. Measurable quantities of influenza A virus were transferred from stainless steel surfaces to hands for 24 hr and from tissues to hands for up ...


7

Article: How influenza virus infection might lead to gastrointestinal symptoms Source study: Respiratory influenza virus infection induces intestinal immune injury via microbiota-mediated Th17 cell-dependent inflammation. The idea is that Influenza virus infection originates in the respiratory tract. In response, the body produces these CCR9+CD4+ Th cells ...


5

I'm going to try and focus on the latter part of your question; if you want to know why the tri- or quadrivalent flu vaccine doesn't provide protection like many other vaccines, that's already been answered. Anyway, the main reason we can't is because there are simply too many. You say 187 (not sure why, 18*11=198) but the truth is that not all H1s are the ...


5

Regrettably, I don't believe we know - we don't actually know why influenza is a seasonal disease in the first place. There are a number of possible theories, discussed in this review, but none of them are compelling enough to be a definitive causal explanation In terms of the difference between Influenza A and B, B mutates at a much lower rate, which may ...


4

The effect on adaptive immunity are often stronger when contracting the flu than for getting the flu vaccination. The backside of this is that the flu is a quite dangerous disease which could end fatally, so getting the vaccine is always preferrable. Getting infected by a specific flu strain (or receive a vaccination against it) generates specific immunity ...


3

Here's a short and simplified explanation. The antibodies that arise in a flu infection are more "intended" to prevent future infections than to clear the present infection. Infections drive T cell responses as well as antibody responses, and the T cells appear a little earlier (peaking at maybe a week) and are probably very useful for clearing the present ...


3

I wouldn't call influenza a vector here, but yes, an infection with the flu virus which results in a full infection can have secondary infections as complications. There are often caused by bacteria which usually live in the respiratory pathway and kept under control by the immune system. This includes pneumonia (either viral or bacterial), inflammation of ...


3

What you call influenza isn't a specific virus which is always the same, but a virus that has numerous different strains. Flu virus is constantly alive on this planet, and there are numerous different types, such as the ones which infect humans, the ones that infect birds, and occasionally a virus that mutates to infect humans although it shouldn't as it ...


2

A vector transmits a disease or parasite from one animal or plant to another. Fruit bats are vectors for Ebola. They are a host to the virus, which can then be passed on to humans. Influenza A, the virus responsible for human seasonal epidemics, is not a vector for other pathogens, although co-infection with two different strains of influenza can give rise ...


2

Short answer: Yes, 156 is generally considered "near" the RBS, e.g. in this paper you can see it mapped onto the structure. For a more general answer, you'll need to sit down and stare at 3D models of hemagglutinins (there are hundreds in the PDB), just like the rest of us. Antibody binding sites are not black and white, and interactions between influenza ...


2

Your understanding of influenza antigenic drift is, unfortunately, hypersimplified and mostly wrong. In particular, your notion that some mutations are more important for antigenic drift because of their effects on structure is at best oversimplified. Rather than spend many paragraphs reviewing the complex patterns involved, I'd suggest you start by ...


2

I don't think there's any universal database containing ongoing, widely representative HI assay output. The Antigenic Cartography group has made available some historical datasets that were used in published articles, such as Influenza A/H3N2 data published in Smith et al. 2004. Science 305:371-376 Data from H1N1pdm09 assays in 2009/2010 (click on the ...


2

A person is said to have a weak immune system when he/she gets infected very frequently. Such individuals tend to get more tired than others, their wounds heal way slower than others. You may want to read more about weak immune systems here. Different symptoms or duration of infection don't decide the immunity status of any individual. Every human body has ...


1

Again, the full answer is too complex to answer here. The CDC has a broad explanation (Selecting Viruses for the Seasonal Influenza Vaccine) and the WHO has a presentation summarizing the process (The WHO Vaccine Strain Selection Process: Review of the Evidence). The major factor for choosing a new vaccine virus is based on surveillance from the preceding ...


1

Quoting Jhung et al. 2011 talking about H1N1 2009 epidemics Although estimates of R0 from past pandemics vary, the R0 of previous pandemic influenza viruses generally range from 1.5 to 1.8 for the 1957 H2N2 and 1968 H3N2 pandemic viruses, and 1.8–2.4 for 1918 H1N1 influenza A strain, with a high estimate of 5.4 by Andreasen et al [see also White et al]. ...


1

There are a number of different protocols, but the canonical one is published at the WHO Influenza site: SEROLOGICAL DIAGNOSIS OF INFLUENZA BY MICRONEUTRALIZATION ASSAY It gives a detailed, step by step protocol.


1

Typically "<10" is converted to a number that is below the limit of detection; often "9". After that simply following the instructions you have yields a GMT of 77.9. If you are using spreadsheet apps such as Excel or Google Sheets, they almost certainly offer "GEOMEAN" functions which will give the number directly.


1

In bacteriophage, the viral capsules serve as vectors for other DNA so frequently that there is a common name for this: transduction. The image below, from the Wikipedia, illustrates the basic process. Here a phage, with pink DNA, accidentally packages up other DNA -- in this case, from the bacterium -- in one of the capsules and thereby serves as a vector ...


1

Contrarily to the main opinion expressed so far, I would say that, in theory, it is possible that an Influenza virus can be a vector for another virus. Here is a paper about using influenza virus as vector for a variety of genes. The same method can be leveraged to engineer an Influenza virus particle that contains, for example, genes coming from another ...


1

While a viral infection such as influenza can lead to secondary infections, it is inappropriate to call it a vector for those other infections. It is not the means by which those other infections are acquired. If a bacterial sinus infection follows upon a bout with the flu, that bacteria was not carried to the patient by the influenza virus. A single ...


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