Archive for the ‘techniques’ 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?

Advertisements

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!

Fall armyworm – and how viruses could help combat the plague.

15 February, 2017

Kenneth Wilson of the Univ of Lancaster has recently written a blog post on the plagues of African and “Fall” armyworms (aka caterpillars, larvae of moth species in the genus Spodoptera) that are currently chewing their way through southern African maize and other crops. I wrote the following as a comment to his blog.

Nice article – which very ably demonstrates the perils of importing agricultural pests from elsewhere!

I am interested that you wrote:
“There are non-chemical, biological pesticides that could also be effective. These are pesticides derived from natural diseases of insects, such as viruses, fungi and bacteria.”

Some years back (OK, nearly 30) Barbara von Wechmar in the then Microbiology Dept was instrumental in our finding a number of insect viruses that were seriously lethal to aphids and green stinkbugs. These were inadvertent discoveries, which happened three times – twice with different viruses for aphids which we were investigating as wheat/barley pests, and once (with two viruses) for stinkbugs causing problems in passionfruit – and were due to observations that high density lab colonies of the insects in question often developed disease that caused rapid colony death. Barbara went on, after characterisation and publication of the viruses by me and Carolyn Williamson, to show that highly effective insecticides could be made by simply grinding up recently dead insects in some buffered saline, sieving the bits out, and spraying the juice onto plants. This worked for aphids, and was especially effective for stinkbugs.

I note that similar phenomena have been seen for a number of insects, including the spruce budworm in North America, and by Don Hendry and others in South Africa for Nudaurelia capensis, the Pine Emperor moth. In the latter case, the larvae can become literal sacs of virus, and bursting of dead caterpillars leaves viruses everywhere in the environment.

It might be a good “boer maak n’plan” type of approach for folk to gather a bucket of these things, feed ’em leaves for a while, see if they start to die – then mulch them in some half-strength (=0.075M) saline and make a spray out of it.

It couldn’t hurt, might help, and would be a pretty good biology lesson B-)

Seriously: you can find insect viruses everywhere you look, and crowding is a really good way of spreading and bringing out otherwise inapparent virus infections, just as it is with humans – with the difference being that insect viruses can reach REALLY high titres in their hosts, and are pretty stable as they are often spread by contact of live larvae with dried juices from dead ones.

References

John C. Cunningham, Basil M. Arif and Jean Percy. THE STATUS OF VIRUSES FOR SPRUCE BUDWORM POPULATION REGULATION. File Report No. 7 January 1981, Forest Pest Management Institute, Canadian Forestry Service

EP Rybicki and MB von Wechmar. Characterisation of an Aphid-Transmitted Virus Disease of Small Grains. Isolation and Partial Characterisation of Three Viruses. J Phytopathology 103, Issue 4 April 1982 Pages 306–322

Cheryl T. Walter, Michele Tomasicchio, Valerie Hodgson, Donald A. Hendry, Martin P. Hill and Rosemary A. Dorrington.  Characterization of a succession of small insect viruses in a wild South African population of Nudaurelia cytherea capensis (Lepidoptera: Saturniidae). South African Journal of Science 104, March/April 2008

C. WILLIAMSON, E. P. RYBICKI, G. G. F. KASDORF  AND M. B. VON WECHMAR. Characterization of a New Picorna-like Virus Isolated from Aphids. J. gen. Virol. (1988), 69, 787-795

Williamson C, von Wechmar MB. Two novel viruses associated with severe disease symptoms of the green stinkbug Nezara viridula. J Gen Virol. 1992 Sep;73 ( Pt 9):2467-71.

 

The Internet Journal of Comprehensive Virology

15 July, 2016

 

See Home Page for details

New Approaches to Vaccines for Human and Veterinary Tropical Diseases. Or maybe sophisticated safari science?

27 May, 2016

The Keystone Symposia organisation held a meeting entitled “New Approaches to Vaccines for Human and Veterinary Tropical Diseases” in Cape Town this week (May 22-26, 2016).  A summary of the meeting was given as:

Human and livestock vaccines can contribute to improved human welfare and income generation by maintaining human health and meeting the demand for meat, milk and fish in developing countries. All of these factors contribute to the growing importance of improving food safety, availability and nutritional security. An important component of this Keystone Symposia meeting will be to stimulate crosstalk between the human and veterinary vaccine communities by highlighting cross-cutting technical advances and new science and knowledge from laboratory and field research. The meeting will also provide a rare opportunity for scientists from the Northern and Southern hemispheres to interact and pool resources and knowledge in the common fight against tropical diseases.”

It succeeded admirably in a couple of these goals: there were delegates there from 31 African countries, as well as many Europeans, Brits and Americans; the juxtaposition of veterinary and medical talks on similar themes created an excited buzz among folk who hadn’t been exposed to the “other”; there was a wealth of dazzling new tech on display in talks, and intriguing insights into how similar – and sometimes, how different – human and animal responses to vaccines were.  It was obvious that approaches used to develop malaria vaccines could benefit animal vaccinology, and indeed, Vish Nene and colleagues from ILRI in Kenya are following some of the same approaches in their work with the East Coast fever disease organism in cattle.

But, there were a couple of buts.  An important one for me was that while there were many Africans there, they were not much exposed in talks, apart from several South Africans. While amazing results were displayed from deep sequencing of antibody gene repertoires of humans and animals and how these developed with affinity maturation; while grand predictions were made as to how bioinformatics and molecular design would revolutionise vaccinology – this was more of the same kind of thing we have got used to in HIV vaccine meetings over nearly twenty years, where Big Science is always going to provide a solution, but never quite gets to it. Why was there no mention of ZMapp antibody therapy for Ebola, when this (OK, I’m biased) was the single most exciting thing to come out of the Ebola outbreak and the international response to it?

I hate to be cynical, but seriously: is there one single vaccine in advanced human trial right now that is a result of intelligent molecular design? Has ANYTHING that has been designed from crystallographic evidence or from cryoEM data actually proven useful in animals or people?  Has dissection of the anti-HIV antibody response development actually, really, taught us anything useful about how we should develop vaccines? Even if South Africans were involved?

I told you I was cynical – and my cynicism was reinforced by a couple of displays of “My Ebola vaccine is better than YOUR Ebola vaccine!”, by folk who shall remain nameless – when it was obvious that both ChAdOx and rVSV vaccines have their merits.

Mind you, the tale of how Ebola vaccines were deployed so rapidly, and how what could have been a 15+ year saga was compressed to less than a year for the rVSV-ZEBOV and ChAdOx vaccines was truly inspirational. It is indeed an object lesson in how to respond to an emerging disease that big companies and philanthropic organisations were able to make many thousand doses of different vaccine candidates in just a few months, and that these could be deployed in human “trials” – actually, genuine deployment in ring vaccination for the VSV candidate – almost immediately.  Adrian Hill of Oxford asked the question, albeit outside the meeting at a seminar in our Institute: if this was possible for an Ebola outbreak, why isn’t it possible for everything else?  Why can’t we do it for Zika virus, and for MERS-CoV too?

If there is a Big Lesson to come out of this meeting, why can’t it be – Let’s Make Vaccines Faster!

Oh, there were big plusses too.  There were fascinating parallels to be drawn in the approaches to developing vaccines for malaria and TB and animal parasitic infections; some of the fancier techniques discussed for human vaccines could obviously find applications in veterinary vaccinology; there were even suggestions for vaccine candidates for animals that were drawn from homologous genes in human and animal apicomplexans (=malaria-like organisms).

I was especially impressed by Dean Everett‘s talk, from the Malawi-Liverpool-Wellcome Trust Clinical Research Programme in Malawi, on “Developing Appropriate Vaccines through Bioinformatics in Africa”: they were actually working in under-developed Africa, on pressing local problems, and making significant inroads into the problems.

And yet, and yet: I have railed elsewhere about the J Craig Venter Institute’s grandstanding over their “synthetic” organisms; while the talk here by Sanjay Vashee on “Synthetic Bacterial and Viral Backbones as Antigen Delivery Vehicle” went some way to redeeming my negative impression of the use of this sort of work, I am still left with the impression that there are considerably easier ways of doing what they claim to be able to. Mind you, one of my colleagues was very impressed with the possibility of making Herpesmids (=infectious, engineerable whole genome clones) in yeast, and would love to do it with their poxvirus collection – so maybe I am a touch TOO too cynical.

I also felt that the final address, by Chris Wilson of the Bill & Melinda Gates Foundation, on: “Cross-Disciplinary Science to Accelerate the Discovery of Vaccines for Global, Zoonotic and Emerging Infectious Diseases” exemplified some of the problems inherent in trying to marry up developed and developing world science, especially in vaccinology.  Part of the talk was great: he gave the best description I’ve yet heard of why it could be feasible to inoculate Aedes spp. with Wolbachia, and why it could significantly impact transmission of flavi- and other viruses.  His description of gene drive technology for wiping out selected mosquito populations was also succinct, and masterly – and appropriate for a developing world audience. Then he got on to how dissection of antibody maturation pathways and flavivirus E protein design could provide paths to good vaccines, and the cynicism kicked in again.

We don’t need either technology to get to vaccines for HIV or for flaviviruses that we can test in the near future, and which could have very significant impacts on millions of people.

Really: we don’t. Extant HIV vaccine candidates are almost certainly better than the RV144 Thai trial vaccine components, and they had an efficacy of 60% in the first year. We already have YFV and dengue and JEV live vaccines – why don’t we use one or several of them in combination with an engineered YFV vaccine to protect against ALL epidemic flaviviruses?  Given the Ebola example, we could deploy vaccines for HIV and for flaviviruses in a year or less, and they would have an impact that would tide us over while fancier products were being made. Seriously: we are always waiting for the next best thing; let’s just apply what we know and what we have NOW to make an impact – instead of, like theoretical physicists, perpetually considering the problem of the spherical horse instead of just going out and riding one.

And that should have been one of the Big Lessons, and we missed it. Instead, there was an element of Safari Science, which is what we in Africa call the kind of endeavour which involves people from the global North flying in to sort out our problems – and leaving with our organisms and disease samples.

Which we could do ourselves, given funding. And that’s another lesson for the folk that do Big Science funding….

 

Your next DNA vaccine might come from tobacco

12 February, 2016

We don’t have much practice at this sort of thing, but seeing as we just got something REALLY cool published, and the man who largely made it possible is now a science writer, we decided to ask him to write a press release.  So he did.  Thanks, Paul Kennedy – take a bow, twice!


“In a pioneering step towards using plants to produce vaccines against cervical cancer and other viruses, University of Cape Town (UCT) researchers have generated synthetic human papillomavirus- derived viral particles called pseudovirions in tobacco plants.

“We’ve succeeded in making a completely mammalian viral particle in a plant – proteins, DNA, everything. That’s enormously exciting,” says Dr Inga Hitzeroth of the Biopharming Research Unit (BRU) at UCT.Dr_Inga_Hitzeroth

In an Open Access study just published in Nature Scientific Reports, BRU researchers report using tobacco plants to create a synthetic viral particle known as a pseudovirion.

A pseudovirion looks like a virus, but it contains no infectious viral DNA. A virus is usually made up of a shell surrounding the virus’s own genetic material. Pseudovirions instead carry whatever DNA the researcher wishes to include within the shell of proteins that make up the outer coating of the virus.

Until now, such particles have only ever been created in yeast or mammalian cell cultures – this is the first time researchers have successfully created pseudovirions in plants.

The BRU is part of a new movement known as biopharming, which means using plants as biological factories. Biopharming has been used to create flu vaccines, potential Ebola drugs, and an enzyme used to treat Gaucher’s Disease in humans. The technique employs the cellular machinery within tobacco plants or other plant cells to manufacture enzymes, antibodies or even the viral capsid proteins (the proteins that make up the shell of a virus), which act as vaccines.

In this research, the BRU has taken biopharming one step further by using plants to create a viral shell that encloses ‘custom’ DNA selected by researchers. “What’s unique here is that DNA that was manufactured within the tobacco plant is now being incorporated into a viral particle to form a pseudovirion,” says Hitzeroth.

The shell of this pseudovirion was that of human papillomavirus (HPV) type 16, the virus responsible for over 50% of cervical cancer cases worldwide.

The BRU team hope this new plant-based technology could one day be used to test future HPV vaccines. First author of the study, Dr Renate Lamprecht, renateexplains: “We need pseudovirions to test any new HPV vaccine candidates. At the moment it is very expensive to make pseudovirions – we need to make them in mammalian cell culture, it needs to be sterile, and the reagents are very expensive.”

All these factors contribute to the high cost of current HPV vaccines, which are actually virus-like particles. Virus-like particles (VLPs) are similar to pseudovirions, but they contain no DNA. Plant- made pseudovirions, as demonstrated by this study, could reduce the cost of testing and manufacturing such vaccines, thus helping to make HPV vaccines affordable where they are needed most: the developing world.

PsVs

Plant-made HPV pseudovirions containing geminivirus-derived DNA

The BRU team compared these new plant-made pseudovirions against the more widely-used mammalian cell culture-produced particles by using what’s known as a neutralisation assay. In this test (which is commonly used to test new HPV vaccine candidates), cells are ‘infected’ with pseudovirions, with or without pre-treatment with neutralising antibodies. The DNA inside the pseudovirion carries a ‘reporter gene’ that produces a protein that can give off a light signal. Thus, an infectious pseudovirion gets into the cell and gives off light, but one that is stopped by neutralising antibodies does not.

“I was jumping up and down the first time I saw the neutralisation results, but I repeated the experiment a few times to be sure, asking myself, ‘is everything correct, are all the controls there?’” explains Lamprecht. “It was a very exciting moment for us when we confirmed that neutralisation had occurred.”

Right now, every laboratory makes pseudovirions for such neutralisation experiments themselves. Dr Hitzeroth hopes that one day, they won’t have to: “we’re in the initial stages, but if we optimise the process and get the yield much higher, we think it’s a product that could be sold all over the world.”

ed ebola

Ed’s Ebola shirt

For Professor Ed Rybicki, Director of the BRU, this achievement was enormously satisfying, as it brought together two strands of his research interests that have co-existed for over 20 years.

“Seventeen years ago, I had the idea to combine making HPV VLPs in plants with a DNA plant virus we were working on, to see if we could make pseudovirions. It took until now for the technology to finally come together, but it shows what can happen in biotechnology if you’re willing to persevere.”

The BRU are also hoping to use this technology to create a therapeutic vaccine, which would also be a first of its kind. The idea would be to use the pseudovirion to deliver DNA that could treat an ongoing HPV infection or even a tumour.

With global acceptance and support for the biopharming movement growing rapidly, it might not be too long before the first plant-produced HPV vaccine is making a difference in Africa and around the world.”


For further enquiries, contact Dr Hitzeroth. For more info on biopharming, check out this Q&A session from Sense About Science.

“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

So that’s what you lot like, is it?

21 October, 2015

My_Stats_—_WordPress_com

Virology Africa 2015: Update and Registration

19 August, 2015

REGISTRATION IS NOW OPEN – VIROLOGY AFRICA 2015

On behalf of the Institute of Infectious Disease and Molecular Medicine of the University of Cape Town and the Poliomyelitis Research Foundation, we are pleased to invite you to Virology Africa 2015 at the Cape Town Waterfront.

VENUE AND DATES:

The conference will run from Tuesday 1st – Thursday 3rd December 2015. The conference venue is the Radisson Blu Hotel with a magnificent view of the ocean. The hotel school next door will host the cocktail party on the Monday night 30th November and in keeping with Virology Africa tradition, the dinner venue is the Two Oceans Aquarium.

IMPORTANT DATES

Early Bird Registration closes – 30 September 2015
Abstract Submissions deadline – 30 September 2015

The ACADEMIC PROGRAMME will include plenary-type presentations from internationally recognised speakers. We wish to emphasise that this is intended as a general virology conference – which means we will welcome plant, human, animal and bacterial virology contributions. The venue will allow for parallel workshops of oral presentations. There will also be poster sessions. Senior students will be encouraged to present their research. We have sponsorship for students to attend the meeting and details will be announced later in the year.

A program outline has been added to the website

WORKSHOPS

Our preliminary programme includes two workshops.

There is a hands-on workshop on “Plant cell packs for transient expression: Innovating the field of molecular biopharming”, with the contact person being Dr Inga Hitzeroth – Inga.Hitzeroth@uct.ac.za. This workshop will run at UCT one day before the conference, 30th November, and a second day, 4th December, after the conference.

The second workshop is on “”Viromics for virus discovery and viral community analysis”. The workshop at UCT will be on 4 and 5 December with the contact person being Dr Tracy Meiring – tracy.meiring@uct.ac.za.

Some of the workshop presenters will be integrated into the conference programme but the practical components will be run at University of Cape Town. Separate applications are necessary for each workshop.

If you are prepared to fund an internationally recognised scientist to speak at the conference or if you wish to organise a specialist workshop as part of the conference, please contact
Anna-Lise Williamson or Ed Rybicki.

For any enquiries please contact
Miss Bridget Petersen/ Email: conference1@onscreenav.co.za or phone: +27 21 486 9111
Ms Deborah McTeer/Email: conference@onscreenav.co.za or +27 83 457 1975

Anyone interested? A candidate virology textbook…

28 July, 2015

I would like to test the response to a Introduction to Virology ebook that I want to develop from my extant Web-based material, given that this is likely to disappear soon with our Web renewal project here at UCT.

Virus_Picture_Book_copy_iba

Download the Virus Picture Book excerpt here. And then please tell me what you think / whether you would buy one (projected price US$15 – 20)?  Ta!