Archive for the ‘history’ Category

Purifying TMV: a blast from the archives

16 February, 2017

We have had an in-house method for purifying Tobacco mosaic virus (TMV) and its various relatives ever since I got to Cape Town – and it was propagated by copying and re-copying of what was effectively an abstract for a talk given at our local Experimental Biology Group quarterly meeting in early 1970, published in the South African Medical Journal.

Marc van Regenmortel was Professor of Microbiology at the time, and had a long history of physicochemical and serological work on TMV and strains and mutants of TMV. He also had Barbara von Wechmar, later to become my PhD supervisor, working for him as a Scientific Officer – and together they came up with an ingeniously simple, easy, high-yielding method to purify TMV out of infected tobacco.

So why do we care now? Well, we’re trying to purify some derivatised TMV [details redacted while patent is sought], and Sue Dennis in my lab could only find techniques that involved extraction with chloroform, PEG/salt precipitation x 2, high-speed centrifugation – all of which sounded unnecessarily laborious, given I knew we had a better method.

Trouble is – I cleaned up my office a while back, and seeing as “we’ll never work with TMV again, will we??”, I’d thrown out all of the old practical manuals that included it.

So I go to the old papers I could find online, and they all referred to “von Wechmar and van Regenmortel, 1970”, with no methodological details. And of course, there was no record of this paper anywhere I could find, not even using [obscure Russian language site details redacted].

Then I chanced upon the very bare bones online archive of the SAMJ, married that up with the much snazzier-looking-but-devoid-of-desired pdfs official site to find issue numbers – and there we were! Via some fascinating side trips through a history of the plague in Cape Town, among other things, but finally, a PDF of the original EBG abstract.

tmv-method

In fact, I have a big section of our coldroom with myriad bottles of purified TMV, all at 5 mg/ml concentration or higher, still infectious, and up to 40 years old – all made by this technique.

tmv sedim

So Sue is about to apply it right now, as she conveniently has a freshly mashed extract of N benthamiana ready waiting, and we have PEG and NaCl…we’ll give the charcoal/Celite a miss this time, because it can get a bit messy, but it is THE way to get pigments out of your virus preps – or even nanoparticles, @FrankBioNano & @Lomonossoff_Lab?

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From plant virology to vaccinology: a personal journey

15 February, 2017

A couple of years ago now, an Editor of the journal Human Vaccines & Immunotherapeutics contacted me to say they would like to profile me as a vaccinologist. Being of a suspicious nature, I immediately inquired how much this would cost me. The encouraging answer was “Nothing!” – so I jumped straight in.

The end result is as near to a current autobiography as I will probably ever get, so I may as well put it up here. So, if you’re interested in finding out what the connections are between a swimming pool in Zambia, not doing Biochemistry (twice), plant virology and making vaccines – click below!

“New Virus Breaks The Rules Of Infection”! No – no, it doesn’t

31 August, 2016

I was prompted to this post by the breathless and much-hyped response to the discovery – the repeated discovery should I say; there was an earlier one that gets glossed over – of a multicomponent flavirus-like virus, this time in mosquitoes.

The actual report was published here: it is a well-done study, describing

“…a genetically distinct, segmented virus isolated from mosquitoes that also exhibits homology to viruses in the familyFlaviviridae and that appears to be multicomponent …, with each genome segment separately packaged into virions”

The authors say

“Although multicomponent genomes are relatively common among RNA viruses that infect plants and fungi, this method of genome organization has not previously been seen in animal viruses [my emphasis]

…which is why there’s all the hype, of course: claiming the virus “…breaks the rules of infection” is simply incorrect, because it is in fact related to very well characterised single-component ssRNA+ viruses of arthropods and mammals – flaviviruses – and infects its mosquito host exactly as these do, except with its genome in separate particles. Which makes it similar to quite a few plant viruses, several of which are, incidentally, probably evolutionarily related to viruses infecting insects – but more later.

Thus, a claim like “…a new study published Thursday is making researchers rethink how some viruses could infect animals” is simply hype.  But it is a sort of hype familiar to plant virologists, who after all showed that multicomponent viruses (=viruses with multipartite genomes packaged in separate particles) existed over 50 years ago – and who also showed that gene silencing was a factor in plant resistance to viruses long before their better-funded animal-researching colleagues got in on the act, but that is another story.

The way in which multicomponency was discovered with plant viruses is interesting: it relied on the fact that plants can respond with local lesions – qualitatively the same as plaques in bacterial or animal cell lawns – to mechanical infection, and that this can be used an an accurate assay of virus titre, as for phages or animal viruses (see here).  It became evident, though, that certain plant viruses produced significantly steeper lesion vs dilution curves than were expected from “one-hit” kinetics, where infection with a single virus particle sufficed to cause a lesion.

This is best shown by a plot like the one below, modified from REF Matthews’ Virology, 3rd Edn, attributed to Lous van Vloten-Doting from 1968.  This shows the curves obtained from accurate and painstaking local lesion assays with the single-component Tobacco necrosis virus (TNV), and the multicomponent Alfalfa mosaic virus (AMV): both are ssRNA+ and have isometric particles, but TNV has a single-component genome, and AMV a tripartite genome packaged in 3 particles.

multicomponent

The insect virus investigators did much the same thing:

“We used a similar approach to assay the nature of segment packaging for GCXV using cell culture plaques instead of leaf lesions. The dose-response curve for GCXV differed significantly from expectations for a single-component virus (i.e., the number of plaques decreased more quickly than expected with dilution of the inoculant)…we used our dose-response curve to estimate the presence of 3.27 ± 0.37 distinct GCXV particles required for plaque formation”

…but with the addition of rapid sequencing techniques not available in 1968, to show that indeed, the different segments were 5 distinct pieces of ssRNA, 3 mono- and 2 tricistronic (=3 ORFs), with the 2 largest monocistronic pieces being similar to flavivirus NSPs and the 3 smallest not encoding anything similar to sequences in the databases.  Four RNAs were essential for infectivity, while the smallest appeared dispensable.  Particles formed during infection of cultured cells were enveloped and 30-35 nm in diameter, considerably smaller than flavivirus virions.

This is a very interesting finding, although not unique: similar viruses were previously found in ticks in 2014, when the authors claimed that:

“To our knowledge, JMTV is the first example of a segmented RNA virus with a genome derived in part from unsegmented [flavi]viral ancestors

They were also wrong: there are a number of viruses for which this could have been said years ago, like the picornavirus superfamily-related comoviruses of plants. These have two-component genomes which both encode polyproteins, one with non-structural and the other with structural ORFs.  In fact, an evolutionary precursor to such viruses could be the more closely picornavirus-related dicistroviruses of insects, which have a classic picornavirus precursor polyprotein ORF split into two, with the structural protein ORF at the 3′ end and the regulatory or non-structural polyprotein at the 5′ end.

I got into this because it irked me mildly that such a fuss was being made of a second group of animal-infecting multicomponent ssRNA viruses, when the multicomponent plant virus precedent and history was VERY well established – but then got more interested when speculation started about what advantage multicomponency could confer on a virus.

I have thought for years that people discussing this generally have it backwards: it’s not that having a divided genome in separate particles offers advantage(s), it’s that it is not a DISadvantage in some circumstances – and particularly where there is no selection against the state.

A reason that multicomponency HAS been seen quite frequently with plant viruses could be that mechanically-transmitted viruses can reach VERY high concentrations in infected plants, and even obligately vector-transmitted viruses (eg: the bicomponent ssDNA begomoviruses, multicomponent ssDNA nanoviruses) reach quite high concentrations in the phloem tissue to and from which they are transmitted, compared to viruses in vertebrates.

This is also true for viruses of arthropods compared to vertebrate viruses: dicistroviruses in aphids can reach concentrations that are comparable to those of viruses like TMV in plants, to the point that aphids inject enough virus into plants that our lab originally mistook Rhopalosiphum padi virus for a plant virus. Moreover, plant virus virions often aggregate into quasi-crystalline arrays which can be hard to separate and which are even visible inside insect vectors, thus virtually guaranteeing that >1 virion will be present in any inoculum, even if significantly diluted.

This is most definitely NOT the case for vertebrate viruses, even where the same virus infects both an arthropod and a vertebrate host: the titre in the latter is guaranteed to be orders of magnitude lower, largely due to a more sophisticated immune system keeping viraemia in check. Thus, high inoculum concentrations relative to vertebrate viruses, and a tendency to aggregate, mean there is no DISadvantage inherent in multicomponency.

Having said this, there may be advantages to having a multicomponent genome: one such is presented in a recent article by Sicard et al. (2013), (thanks, @LauringLab and @DiagnosticChick!) in a study of the ssDNA nanovirus Faba bean necrotic stunt virus (FBNSV), which has an 8-component genome of ~1 kb/segment, encapsidated in 8 virions. They proposed:

“…that the differential control of gene/segment copy number may represent an unforeseen benefit for multipartite viruses, which may compensate for the extra costs induced by the low-frequency segments”

Thus, multicomponent viruses may achieve the sorts of gene dosage control only possible in viruses with larger genomes, by virtue of having multiple genome components rather than control elements which add genomic bulk.

Another possible advantage that I recall being touted by plant virological luminaries is the ease of reassortment compared to recombination: this is exemplified by the reo- and orthomyxoviruses, albeit in vertebrates, where they are constrained by having to have all genome components in the same capsid to guarantee infectivity.

I think Vincent Racaniello is correct in the breathless article I quoted in opening, where he is quoted as saying

“There’s so much we don’t know about viruses…We should always expect the unexpected.”

Absolutely. And I think it’s a safe bet that a LOT more multicomponent viruses will be found in arthropods – and even in some vertebrates, to which they will have been transmitted by arthropods. Because that’s the link between many of these viruses: an evolutionary history that involves plants and arthropods, or arthropods and other animals, at an early stage of life on land. Because that’s all there was for advanced eukaryotes, early on: primitive vascular plants, insects that preyed on them and on each other, and protists.

So: will smallpox come back to kill us, from the melting permafrost??

17 August, 2016
Variola virus, the agent of smallpox.  Image courtesy Russell Kightley Media.

Variola virus, the agent of smallpox. Image courtesy Russell Kightley Media.

There has been a lot of tweeting today about how Smallpox Will Come Back From The Grave And Kill Us All: see here, here and here for lurid examples.

This is alarmism at its insidious best: shouting out a headline, based on flimsy evidence, that says “We’re all going to die!” or similar nonsense.

Really: this IS nonsense.  Some corpses were found in the permafrost in Siberia, that MAY have had smallpox-like lesions on them, and from some of which which smallpox virus DNA could be recovered – presumably by PCR.

This does NOT constitute a threat of live virus being present, or escaping from the corpses even if it WERE there.  I have railed on about this sort of thing before, and I am as unconvinced now as I was then, albeit with SOME reservation about the possibility for smallpox.

"Pithovirus sibericum", from Jean-Michel Claverie and Chantal Abergel

“Pithovirus sibericum”, from Jean-Michel Claverie and Chantal Abergel

I can believe you could get live anthrax: those spores are incredibly tough, and can last for many years in soil, let alone in ice. I could also believe that one could find live megaviruses – the so-called pitho- and molliviruses – in permafrost, because their putative hosts are unicellular protozoans and because they are also seriously stable.

But smallpox? The virus is probably not as stable as the megaviruses mentioned; it relies for infection on its structure, which has membranes integral to it – AND it infects people, who, when they die, don’t cool down very quickly, and whose cells release all sorts of nasty enzymes (lipases, proteases) as they die. Which could be expected to chew up most things, including poxviruses.

Oh, sure, poxviruses CAN survive for years at a pinch – in the form of dried secretions or scabs, which, because they are dehydrated and full of protein, tend to stabilise virus particles. This is how the old variolators and vaccinators (literally: people who used variola or “vaccine” to vaccinate against smallpox) used to preserve their inocula, when they weren’t using fresh material.

Melting tundra is not like that, I will note: bodies with intact virions in them will thaw and rot all over again, and that rotting will reduce what little virus there may be even further.

So I am not a believer in Death From The Permafrost!

And nor should you be.  But it might not hurt for someone qualified to test whether or not there IS live virus in frozen samples, by culturing an extract?

AIDS: 35 years old this month

6 June, 2016
HIV particle.  Russell Kightley Media

HIV particle. Russell Kightley Media

I was alerted via Twitter this morning to the fact that the CDC’s Morbidity and Mortality Weekly report that reported the first recognition of the syndrome we now know as AIDS, was published on 5th of June 1981.  It appears – sadly – that their archive only goes back to 1982: there’s a missed chance to expose some history, CDC?!

Thirty five years: I was a novice lecturer, just starting out; the Web was still science fiction; HIV and its relatives were still undiscovered – but they had already started to spread out of Africa, after smouldering away in the tropical forests of Gabon and the Congos for decades.

I started an information web page on HIV/AIDS back in 2000 or so, largely in response to the ridiculousness of Thabo Mbeki’s pronouncements on the virus and the disease: thanks to tectonic shifts in the UCT Web policy, these disappeared – but thanks to the invaluable Wayback Machine, can still be found.  If you want a slice of history, and to see how bad I am at designing web pages, go take a look. Still MOSTLY valid, although many of the links are now dead – sic transit the web content, unfortunately!

And here we are in 2016: I’m now an elderly academic, the Honours student who alerted me to the fact the the “GRIDS” syndrome virus may have been identified in 1983 is now a senior Professor and distinguished HIV researcher – there’s a whole career there, Carolyn! – and HIV/AIDS is still with us. And unfortunately, Thabo Mbeki is still being wilfully if not malevolently ignorant, and I am still feeling it necessary to crap on him.

At least the pandemic appears to have peaked in terms of incidence, and ARVs are increasingly good and employed widely; however, we still don’t have a decent vaccine, and people are still being infected. This pandemic will last out my career – but hopefully not those of some of the people I have trained.

Thabo Mbeki rides again. Let’s knock him off his horse, then!

7 March, 2016

Sixteen years ago, two colleagues and I wrote a letter to Nature expressing our concern about our then-President Thabo Mbeki’s denialist views on HIV and AIDS – views he then tried to push into national policy, and which almost certainly were highly influential in delaying the rollout of ARVs in South Africa.  I was also active for several years in the media and in public lectures in trying to negate some of the damage he was causing – and I was very relieved when he took a back seat eventually, and then effectively vanished from the public stage.

However, in an unwelcome development as of this week, it appears that Mr Mbeki has finally, in his ongoing quest to rewrite history, addressed the elephant in the room: his views on HIV/AIDS.

To say this “letter” is self-serving would be to pay it a compliment.  Indeed, he himself has this to say concerning the awful “Castro Hlongwane, Cats, Geese, Caravans, Foot and Mouth and Statistics…” that he almost certainly was the main author of, back there in 2002:

“Thirteen (13) years later today I would stand by everything said in this excerpt and still ask that the questions posed should be answered by those who have the scientific capacity to do so!”

So in other words, he still holds with much of the rubbish he wrote then.  Right – well, so will I revisit something I helped write, back in 2000, after reading that Mbeki had written to Bill Clinton to dispute conventional ideas on HIV/AIDS.

Nature 405: 273, 2000

AIDS dissidents aren’t victims – but the people their ideas kill will be

Sir – As South African scientists working in the field of HIV/AIDS vaccine research, we are extremely concerned about the letter president Thabo Mbeki recently sent other heads of state (Nature 404, 911; 2000). As an individual Mr Mbeki is entitled to his point of view, but as our head of state we feel he risks binding our country to an untenable position.

We would like Mr Mbeki and others to consider how the mass of South Africans would react if he were to give a sympathetic ear to unrepentant proponents of apartheid. His willingness to be influenced by people with no credibility causes as much anguish to those of us working to combat HIV/AIDS.

The simple facts, as shown by a huge volume of scientific and medical research, are that HIV causes AIDS; that in Africa (as in other developing regions) the disease is mainly spread heterosexually; and that AIDS kills poor people in disproportionate numbers. We most emphatically do not need to revisit the debate on the causation of AIDS. What we do urgently need is to educate, train and medicate, to save lives.”

This is germane, because Mbeki has the gall to go back to his Castro Hlongwane crap at the end of his latest letter, and say:

“Beneath the heartening facts about decreased mortality and increasing life expectancy, and many other undoubted health advances, lie unacceptable disparities in wealth. The gaps between rich and poor, between one population group and another, between ages and between sexes, are widening. For most people in the world today every step of life, from infancy to old age, is taken under the twin shadows of poverty and inequity, and under the double burden of suffering and disease.”

“Castro Hlongwane…” says: “Given that our minds on this matter (of HIV and AIDS) have become thoroughly clogged by the information communicated by the omnipotent apparatus, a miracle will have to be achieved to get all our people to use their brains, rather than perish on emotional responses based on greatly heightened levels of fear.”

Really, Thabo??  You’re going to harp on about poverty, again?  Oh, and the “omnipotent apparatus” that is Western Pharma, and of course US capitalism?

Please do us a favour, Comrade: go back to your pipe, and your old friends Johnny and Jack, and stop trying to justify the indefensible.  And I will close with something I wrote for the Mail & Guardian on March 1st back in 2002:

“It does not seem to matter what happens in our country; it does not matter how many people try to engage the slippery python that is the president’s policy and thinking on HIV/Aids; it does not seem to matter how many people die of Aids, and how many babies are needlessly born with HIV – there remains the stubbornness and wilful failure to comprehend that is leading us into disaster. Mr Mbeki, you make an idiot of yourself, and fools of us all for putting up with your views. Leave health policy alone, or resign. Please.

Ed Rybicki, Pinelands”

I see no reason to change my views either, Comrade.

“Online ‘recipes’ for bird flu virus add to bioterrorism threat!” No. No, they don’t.

10 December, 2015

The means of engineering potentially deadly avian influenza is freely available on the internet.

Despite continuing global efforts to contain avian influenza, or bird flu, the means of engineering this potentially deadly H5N1 virus to render it transmissible to humans is freely available on the internet. So too are similar instructions for engineering a virus like the “Spanish flu”, which killed some 50 million people in the pandemic of 1918-19.

The digital floodgates opened in 2011 when a peak US regulatory watchdog came down in favour of scientists seeking to publishing their work engineering the H5N1 virus. The decision to uphold such “scientific freedom” was and remains, highly contentious among the global scientific community. Its implications, however, are readily available as online “recipes” for potentially dangerous viruses, which add a new risk to the already considerable challenges of maintaining global biosecurity in the 21st century. For all the recent advances in biomedical science, drugs, vaccines and technology, this is a challenge we remain ill-equipped to meet.

Read more: http://www.theage.com.au/comment/online-recipes-for-contagious-diseases-means-australias-bioterrorism-threat-is-real-20151208-gli97v.html#ixzz3tvWn63AE ;
Follow us: @theage on Twitter | theageAustralia on Facebook

Sourced through Scoop.it from: www.theage.com.au


 

OFFS: seriously!  Again?!  Someone else has just discovered that entire virus genomes are freely available via PubMed, along with papers on gain-of-function experiments, and immediately leaps to the conclusion that this means “…the means of engineering this potentially deadly H5N1 virus to render it transmissible to humans is freely available on the internet”.

I’m sorry, this is being simple-minded to the point of parody.  I have written elsewhere – here in ViroBlogy, and in Nature Biotech’s Bioentrepreneur blog section – on how it is MOST unlikely that bearded fellows in caves in Afghanistan or remote farms in Montana are going to whip up weaponised batches of H5N1 flu or Ebola.

Yes, the papers are available; yes, the sequences necessary to make a potentially (and I say potentially advisedly) deadly virus are available online; yes, one can bypass the blocks on getting resynthesised genes in developing countries (hint: China).

But could anyone outside of a sophisticated lab environment use these to make anything nasty?

No.

Seriously, no.

Just think about what you would need to make weaponised flu, for example.  There are two ways to go here, these being the totally synthetic route (“mail order” DNA – HATE that term!), with some serious molecular biology and cell culture at the end of it, and the “natural” route – which would involve getting a natural and nasty isolate of H5N1 / H7N9 / H9N2, and being able to culture it and engineer it as well.

Both routes require a minimum of a serious 4-yr-degree-level training in microbiology / mol biol, as well as laboratory resources that would include incubators, biohazard cabinets, and disposables and reagents that are not on your normal terrorist’s priority purchase list.

In fact, the kinds of resources you’d find at a University or Institute Infectious Disease unit – or state-sponsored biowarfare lab.

Seriously, now: in order to use the information that is “freely available”, you’d have to do what amounts to an entire postgrad degree’s worth of work just to set up the kinds of reverse genetics necessary to WORK with recombinant flu, presuming you already had an isolate, and even more than that if you were to start with synthesised DNA and try to recreate infectious virus.

Again, this is the kind of work they do in biowarfare / biodefence labs (funny how they’re pretty much the same thing, isn’t it?) – because it’s finicky, expensive, laborious – and potentially dangerous to the researcher.

And it’s interesting that the only rumoured escapes of biowarfare agents have been of flu in 1977 in the old Soviet Union, and of anthrax in Sverdlovsk in the USSR in 1979. And in the US in 2001, and again in 2014.  ALL of them from official facilities, I will discreetly point out.

Oh, there have been rumours that Saddam’s Iraq weaponised camelpox; that the USSR/Russia cloned Ebola into a poxvirus; that Al-Qaeda tested anthrax – but the first two took state resources, and if the third happened at all, it’s nothing that the UK and USA and friends hadn’t already done in the 1940s.

IT IS NOT THAT EASY TO MAKE RECOMBINANT VIRUSES.

Seriously.

See on Scoop.itVirology News

Testing out a textbook on Virology

5 December, 2015

Like my recent books on History of Viruses and Influenza, I’m constructing an ebook Introduction to Virology textbook – and I’d like people’s opinions.

It’s going to look something like this:

Virus_Picture_Book_copy_2_iba

 

It will be based on my web pages that were so cruelly destroyed, but will be PROFUSELY illustrated, using all of the bells and whistles built into the iBooks Author app, with liberal use of Russell Kightley’s very excellent virus picture library.

And I will sell it for US$20 or less.

Tell me what you think of the taster – and there will be more.

Rounding Up The Last Of A Deadly Cattle Virus

16 November, 2015

Rinderpest, or cattle plague, was declared eradicated in 2011. But many research institutes still have samples of the rinderpest virus in storage. Disease experts want those samples destroyed.

Sourced through Scoop.it from: www.npr.org

I have written a lot about rinderpest, and covered it in my book on virus history, as well as covering the debate on whether or not smallpox virus stocks should be eliminated.

And if they haven’t yet, despite years of debate, why should rinderpest virus stocks?

Consider: we have an effective vaccine(s); we still have the related peste des petits ruminants virus knocking around, with vaccines to it – so why shouldn’t stocks of the live virus strains be preserved?

How many viruses have in fact made it out of fridges, and back into the world?  Well, there was that purported 1977 H1N1 release in Russia/Mongolia…but can anyone think of another well-documented one?  Just one?

The fact is that it is FAR easier to deliberately spread endemic viruses around – like foot-and-mouth disease virus – than it would be to reactivate and spread something from a lab freezer.

Rather let us conduct an inventory of who has what, consolidate it like they did with smallpox, and forget about the unknowable, which is obscure freezers in far-flung rural centres where no-one remembers what is there – and where powercuts have probably thawed the samples more than once.

See on Scoop.itVirology News

So that’s what you lot like, is it?

21 October, 2015

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