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Posts Tagged ‘remdesivir

Covid-19 – conspiracies, remdesivir

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tricky micky plumpeo, vying with old frumpy to become US muckraker-in-chief

Canto: So, getting back to Covid-19, I want to look at two unrelated issues – the limited approval of remdesivir as a treatment, and the claim by the US government that the virus escaped from a lab in Wuhan. What do you think?

Jacinta: Well let me briefly address the second matter – I haven’t yet looked into the claim, but I will say that, IMHO, the current US federal government is possibly the largest misinformation machine on the globe at present, and I won’t be happy till I see every member of that non-administration in jail.

Canto: Okay, be prepared for a life of misery. I agree though, that Pompeo is a slimeball, and it’s very likely that this is largely designed as another blame-shifting distraction by the US maladministration. I don’t remember hearing about this from any news source before Pompeo announced it.

Jacinta: Well it’s interesting that, in investigating this, we have to contend with, and generally ignore, two of the most untrustworthy governmental sources of information on Earth, the USA and China. So thank dog for independent journalists, scientists and investigators. We need them so much at this time. The Washington Post has a 2000-word article on the issue, posted on May 1, undoubtedly in response to moves by Frumpy & co to get the US public to blame China for the pandemic. The article describes an assessment from the US intelligence community:

While asserting that the pathogen was not man-made or genetically altered, the statement pointedly declined to rule out the possibility that the virus had escaped from the complex of laboratories in Wuhan that has been at the forefront of global research into bat-borne viruses linked to multiple epidemics over the past decade.

Canto: ‘Pointedly declining to rule out’ means very little. They’re making a point of saying it’s possible? Isn’t it more likely to have come from the ‘wet markets’ – wet with blood that is – as a result of that traditional Chinese fondness for dining and medicating on exotica?

Jacinta: ‘Murky’ is how the WaPo describes the origins. Some scientists are saying it’s highly likely to have been ‘naturally transmitted’, others, not so sure. But the thing is, the scientists are the ones to trust on this, certainly not the Chinese or US governments. And even then you need to check those scientists’ allegiances.

Canto: I should also point out, as so many scientists are doing, that now is not the time for playing the blame game. Knowledge is power, and we need to be pooling our global resources, and our knowledge, to combat this and future pandemics. We need to try and build trust, not to sow distrust. And this isn’t to say that accidents can’t and don’t happen in virology and microbiology labs around the world, including in the USA.

Jacinta: The WaPo also has much to say about renowned virologist Shi Zhengli, team leader at the Wuhan Institute of Virology, which is being targeted by the Trump administration’s propaganda campaign. According to Shi, ‘the institute never possessed the SARS-CoV-2 virus’, while Wuhan’s health commission has found, or claimed, that the first person who died of the virus purchased goods at the Huanan Seafood Wholesale Market.

Canto: So it may have come from seafood?

Jacinta: Don’t know. Probably they sold more than seafood there, or it was part of a wider market. Anyway, many virologists, including US scientists who’ve worked with her, vouch for Shi’s extreme rigour and brilliance. But clearly that won’t stop the US government’s attempt at character assassination. I’ve heard they’re trying to say, or infer, that the virus was engineered at the Wuhan lab – and no doubt millions of Yanks will believe this brilliant theory, that the virus was engineered by mad scientists and then let loose to kill thousands of their own people before being unleashed upon the world – to be followed up by Chinese chem-trails, no doubt.

Canto: And not just Yanks. Anyway let’s move on to a happier topic. Remdesivir.

Jacinta: Well the news is that the FDA in the USA has issued an Emergency Use Authorisation for remdesivir, and the Gilead company which owns this pharmaceutical, has issued a company statement (on May 5), and here’s a quote:

Gilead’s overarching goal is to make remdesivir both accessible and affordable to governments and patients around the world, where authorized by regulatory authorities…. Gilead is in discussions with some of the world’s leading chemical and pharmaceutical manufacturing companies about their ability, under voluntary licenses, to produce remdesivir for Europe, Asia and the developing world through at least 2022. 

I’ve listened to an interview with Gilead’s CEO Daniel O’Day, and he was making all the right caring-and-sharing noises…

Canto: Can we revisit what remdesivir is and does?

Jacinta: Of course. For starters it’s not a cure, it’s essentially ‘an investigational antiviral drug’ (I’m quoting again from the company statement) which, O’Day is careful to point out, ‘has not been approved by the FDA for any use’ (meaning presumably besides this emergency use). He also admits that the drug is the subject of multiple ongoing clinical trials and ‘the safety and efficacy of remdesivir for the treatment of COVID-19 are not yet established’. It’s a nucleoside analogue, one of many that have been formulated over the years, and dozens have been approved for use in treating viruses, cancers, bacterial and other pathogens. Nucleoside (and nucleotide) analogues are designed to resemble naturally occurring molecules used to build the RNA and DNA so essential to our biology. Some of the best-known nucleosides are cytidine, thymidine, uridine, guanosine, adenosine and inosine. The difference between a nucleoside and a nucleotide is that nucleosides are nucleobases linked to a sugar molecule while nucleotides are linked to phosphate groups (oxygen and phosphorus).

Canto: And the key is that in creating an analogue which functions differently from the real thing, they’re trying to obstruct the replication of the pathogen that takes up this analogue, right?

Jacinta: Yes, you’re getting it. Remdesivir actually has several modifications to the nucleoside structure while still functioning as an analogue – that’s to say it still manages to trick the virus into utilising it, and so becoming dysfunctional in terms of replication. A professor of chemistry and biochemistry, Katherine Seley-Radtke, describes the process in relatively simple terms:

Remdesivir works when the enzyme replicating the genetic material for a new generation of viruses accidentally grabs this nucleoside analogue rather than the natural molecule and incorporates it into the growing RNA strand. Doing this essentially blocks the rest of the RNA from being replicated; this in turn prevents the virus from multiplying.

She writes that remdesivir is a three-times-modified version of the adenosine molecule. Firstly, it’s a ‘prodrug’, in that it has to be modified in the body before it becomes active. The active form has three phosphate groups and is then recognised by the RNA polymerase enzyme of the virus. The second modification is a carbon-nitrogen group attached to the sugar, which is the key to terminating the RNA strand’s production. The third modification is a little change to the molecule’s chemical bond, replacing one nitrogen with a carbon, which prevents one of the enzymes of the virus from recognising and excising ‘foreign’ nucleosides. Remdesivir’s modified adenoside remains in the RNA chain, ultimately terminating further production. Got all that?

Canto: I refuse to confirm or deny. But I can read too. There’s a proper clinical trial of the drug being conducted in the USA at present, and other trials elsewhere. Preliminary results show faster recovery in a statistically significant number of patients, but it isn’t a cure, and will likely be part of a cocktail of treatments as other and hopefully even better antivirals are formulated. This follows the approach to treating other dangerous viruses such as hepatitis C and HIV. It’s about getting the death rate, and the badly-affected rate, down. This is as important as a vaccine, at present.

Jacinta: And I’ve heard it’s quite a tricky drug to manufacture, so getting supplies up and sharing expertise globally will be key factors in saving lives.


Written by stewart henderson

May 7, 2020 at 4:17 pm

Covid 19: some stuff on remdesivir

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remdesivir, somewhat simplified, with its central phosphate group

Canto: So there’s this promising new antiviral drug that researchers are working on. Remdesivir. Terrible name. Why not something more hard-hitting like rambovir or rockyvir?

Jacinta: Well I’m not sure it’s an American drug, and I don’t think it’s new. It’s new for Covid-19. Everything’s new for Covid-19. And here we should repeat the standard caveat: ‘No specific agent has yet been demonstrated to be clinically effective in the management of Covid-19’.

Canto: Well done. So I’m reading this online article from a week or so ago – and a week’s a long time in Covid-19 – on the website of the Medical Journal of Australia, and it tells me that the antimicrobial remdesivir is ‘an investigational nucleotide prodrug’ – glad it’s not one of them antidrugs – and was used on the first diagnosed Covid-19 sufferer in the US. So maybe it is American. The article doesn’t say anything about its effect on the patient, but apparently it was first developed as a potential therapy for Ebola, and there’s some laboratory evidence that it can inhibit the replication of SARS-CoV-2.

Jacinta: That’s right, so four clinical trials have already begun in the US to test the effects of remdesivir, and another two are registered in China.

Canto: Well according to this media release only yesterday (April 17) from the National Institutes of Health (NIH) in the USA, they’ve already been testing the drug on poor old rhesus macaques…

Jacinta: They infected em? Bastards.

Canto: History is written by the victors my friend. And also by those who can actually write. Anyway, they responded very well to early treatment with reduced clinical signs and lung damage in a study designed to simulate treatment procedures for human patients in a hospital setting…

Jacinta: That’s nice. They got to sleep in real beds, like middle-class macaques.

Canto: Maybe. Of course, none of this has been peer-reviewed yet, but it’s very promising. But let me give you the total lowdown. You know that there have to be control groups, right?

Jacinta: Uhhh – uh-o. So… Let me see, they were all infected with the virus, but only some got the remdesivir, right?

Canto: Well of course they had to make the comparison. So they had two groups of six rhesus macaques, and they infected both groups with SARS-CoV-2. Then 12 hours later the treatment group received an injection of remdesivir. Sorry about the other group. After that the treatment group received a booster injection every day for the next six days. The initial treatment was timed to more or less coincide with the animals’ highest projected viral load. They first examined the animals 12 hours after initial treatment, and the treatment seemed pretty effective, only one still showed some mild symptoms, while in the control group they all displayed ‘rapid and difficult breathing’ …

Jacinta: Called dyspnoea in medical lingo.

Canto: Thank you. So the study continued for seven days, and over that time the treated monkeys were found to have significantly less virus in, and damage to, their lungs than the untreated.

Jacinta: So what happened to the untreated monkeys after that?

Canto: I might say ‘don’t ask, don’t tell’, but I think it’s reasonable to assume that after seven days they were treated with remdesivir and recovered. And that they chose a short, seven-day testing period so as not to endanger any monkey lives?

Jacinta: Hmmm. I don’t know too much about monkey business… Anyway, this remdesivir is obviouly promising and we must watch out for the results of other trials. But what is this remdesivir? What exactly is an antiviral, or a ‘nucleotide prodrug’, and do they all act in the same way? I know they’re not vaccines, they don’t induce antibodies, so how do they suppress the infection?

Canto: Okay, so our first stop on our info crawl is Wikipedia. Think of antivirals as a counterpart to antibiotics, aimed at viruses rather than bacterial pathogens, except that, unlike most antibiotics, their aim is to suppress rather than to kill the pathogen.

Jacinta: Really? Why not aim to kill the virus?

Canto: I don’t know, perhaps that’s not so easy with viruses. Anyway, while most antivirals target specific viruses, some are broad-spectrum, and I suppose remdesivir is one of those, since it was also successful against MERS, another coronavirus, and was first developed to combat Ebola virus, which isn’t a coronavirus as far as I know.

Jacinta: Remdesivir was earlier described as a nucleotide prodrug. A nucleotide is the basic structural unit of a nucleic acid such as RNA. A prodrug is by definition an inactive biological or pharmacological compound that can be converted within the body to have active drug properties. So the field of antiviral drug research has developed a lot, especially as a result of the HIV epidemic, and those that followed. All of this has expanded our knowledge of how viruses enter hosts and proliferate. SARS-CoV-2 is a set of RNA nucleotides surrounded by a protein capsid, or capsule, over which is a lipid envelope. It enters the host via the spike protein, and through this membrane fusion it infects host T lymphocytes – white blood cells that form a part of our immune system.

Canto: Yes, and trying to describe it all in lay terms – so that we understand it – is damn difficult. We know remdesivir has been somewhat effective for a broad spectrum of action against RNA viruses, and I note in this abstract that it’s ‘a nucleotide analog inhibitor of RNA-dependent RNA polymerases (RdRps)’ My guess is this means it acts like a nucleotide, inhibiting these RDRps. An RNA polymerase, I’m learning, is an enzyme (a type of protein) that’s ‘responsible for copying a DNA sequence into an RNA sequence, during the process of transcription’. But maybe an RNA-dependent RNA polymerase works on RNA, in the absence of DNA. So presumably remdesivir inhibits this essential enzyme from carrying out the transcription process that replicates the virus.

Jacinta: Maybe. By the way, as we travel the net on our info crawl, we’ve discovered some amazing stuff, such as this Covid-19 pandemic series of ongoing videos from a source called MedCram that began in late January and traces the spread, and the drama. The series begins with these words: ‘one of the things that’s in the news and hopefully goes away real soon is the coronavirus epidemic from 2019…’ That, to me, was more compelling than any advertising hook I’ve ever read.

Canto: Yes I’m keen to watch the whole series. Anyway, I believe remdesivir, also called RDV, has been used in an unauthorised way on human subjects already, and news from this Chemical and Engineering News website is that, understandably, interest in the drug and in scaling up production is reaching fever pitch, with a lot of pressure on Gilead, the company that presumably has a patent on RDV.

Jacinta: Of course, as we’ve already pointed out, this is exactly not the time for one private company to get precious about its rights to profit. Scaling up, assuming the drug’s effectiveness can be confirmed, should involve multiple labs in multiple countries. Having said that, producing a drug like RDV, described as a ‘medium complexity project’ compared to an apparently simpler drug such as the antimalarial drug hydrochloroquine, already involves a chain of companies and suppliers in a multi-step process. Every step in the process would need to be efficient, to prevent bottlenecks. Scaling-up also raises questions – remember Tamiflu? Our government stockpiled it in vast amounts in spite of damning analyses by the Cochrane Collaboration and others about its limited effectiveness and problematic side-effects. We don’t yet have proper analysis of RDV’s effectiveness, and we don’t know how much of it might be required, because nobody can predict the eventual course of this pandemic.

Canto: All true, but right now people are dying, and this is clearly the worst pandemic in more than a century. There are of course candidates other than RDV, it would be unwise to focus on just one, but public and private resources should be combined to bring any possible effective treatment to fruition. That’s what I reckon.


How coronavirus kills: acute respiratory distress syndrome (ARDS) & Covid-19 treatment (one of the first in an excellent ongoing video series on the Covid-19 pandemic)

Written by stewart henderson

April 21, 2020 at 12:58 pm