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8

Well, we can work this out empirically. We know that the average molecular mass of a base of a RNA is 339.5 g/mol. However to calculate the approximate molecular mass of a single-stranded RNA molecule, you multiply the number of bases by 320.5 and add 159 (same source). This means for a single-stranded molecule of 1000 bases, it will have a molecular mass of ...


8

For Covaxin (BBV152), SARS-CoV-2 was inactivated by treatment with β-propiolactone [1]. β-propiolactone reacts with and modifies, among other things, nucleic acids, thus preventing their replication [2]. [1] Yadav P, Ella R, Kumar S, et al. 2020. Remarkable immunogenicity and protective efficacy of BBV152, an inactivated SARS-CoV-2 vaccine in rhesus macaques....


7

The spike proteins expressed by cells that take up mRNA or ChAdOx vaccines are modified so they cannot induce membrane fusion. However, the research article you refer to indicates that circulating spike protein damages endothelial cells simply by binding ACE2, which suggests vaccine derived spike protein could still cause this kind of damage if it enters the ...


5

What you describe, creating the spike protein independently and delivering it, is exactly what is done by subunit vaccines, such as the COVID-19 vaccine developed by Novavax. As already noted in @Amanda's answer, mRNA is great at amplifying a delivery, so you need a lot less to be delivered. The manufacturing process for the vaccine itself is a lot more ...


4

I TRY to answer. First of all, no we cannot be 100% sure that the primers are effective against all strains. However, the strains that are under media attention right now are due to variants in the spike protein, while RT-PCR primers are designed on different genes. One WHO document (I do not know if it's the official guideline) targets RdRp (RNA-dependent ...


3

No, some strains contain mutations causing partial or complete failure of amplification of at least one of the test targets. Here's an FDA bulletin on the issue from January: https://www.fda.gov/medical-devices/letters-health-care-providers/genetic-variants-sars-cov-2-may-lead-false-negative-results-molecular-tests-detection-sars-cov-2 As the bulletin notes, ...


3

The mRNA vaccines encode a mutant version of the spike protein in which the structural transition needed to to fuse membranes is blocked. This was done to make the immune response focus on the pre-fusion state, which is much better for neutralizing the virus. From https://cen.acs.org/pharmaceuticals/vaccines/tiny-tweak-behind-COVID-19/98/i38: Fortuitously, ...


3

I'm not going to give you the final answer, because this is still a class assignment, after all, but I'll give you some tips. What you are looking at is a Western blot of whole-cell extracts from a cell line called Vero, either on its own (vertical ane 9, from numbering across the bottom) or infected with various viruses carrying specific genes, as indicated....


3

This is a bit complicated from far away, but I will share a few thoughts on it. The occurence of primer dimers depends on the design of the primers (sometimes they are inevitable due to sequence limitations), but then they also show up in the negative controls. If they are not present in the negative controls (meaning: never), I would not expect them to be ...


2

While I'm not sure about the petri dish experiment, I will answer the main question I think you're asking: how important is the air that escapes out of the sides/top of the mask? This question is answered with really cool visuals in this paper: Visualizing the effectiveness of face masks in obstructing respiratory jets. While the main point of the paper aims ...


1

Each individual case will be different, but in general it is useful to ask "why did the vaccinated person still catch the Covid disease?" If they caught the disease because the vaccine had essentially no effect on them (for example, some immunocomprimised individuals who cannot generate an appropriate immune response), then they are likely to be at ...


1

Actually, neither A nor B in the example are a correct interpretation of a false positive rate, because there isn't enough information provided to determine a false positive rate. In the terminology of clinical diagnostic testing evaluation, testing outcomes can be classified into one of four fundamental categories: True positive, false positive, true ...


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