Posts Tagged ‘vaccine’

Emergency response vaccines for H5N1 influenza in South Africa

1 November, 2013

Our group has been working for some time now – since 2006, in fact – on investigating the feasibility of providing South (and southern) Africa with emergency response pandemic influenza vaccines.  The research was initiated after the Virology Africa 2005 conference that Anna-Lise Williamson and I organised in the Cape Town Waterfront in November of that year – when a senior WHO official warned us in his talk that “…if a pandemic hits, you are on your own: no-one will give you any vaccine”.

A group of us sat down afterwards, and discussed the feasibility of looking at emergency response vaccine(s), given that we had no capability in the whole of Africa to make flu vaccines.  Anna-Lise and I put together a proposal, with the highly pathogenic avian H5N1 influenza A as a target, which was funded on a once-off one-year basis by the Poliomyelitis Research Foundation (PRF) here in SA for 2006 – and then again by the PRF as a three-year Major Impact Project  (MIP) from 2008-2010, and subsequently to a lower level by both the PRF and the Medical Research Council of SA.  What made it all the more impressive for a South African project was that we had proposed expressing a protein-based vaccine in plants – quite a revolutionary prospect at the time, but something that followed on from the highly successful production of Human papillomavirus virus-like particles by transient expression in Nicotiana benthamiana by  James Maclean, working as a postdoc in our lab at the time.

However, some of the most important work was done early: James was very quick to get the haemagglutinin (HA) gene for the A/Vietnam/1194/2004 strain of H5N1 synthesised by GeneArt in Germany, and cloned into the same Agrobacterium tumefaciens plant expression vectors from Professor Rainer Fischer’s lab in Aachen, Germany, that had been used for HPV.  His initial work showed that large amounts of HA protein could be produced, both as soluble protein which lacked a membrane localisation domain, and as the membrane-bound form.  This work formed the basis for a patent application on the transient expression of H5 HA that has now been granted.

Subsequently, when the PRF MIP started, we employed Dr Elizabeth (Liezl) Mortimer and Ms Sandiswa Mbewana to further the work: with collaborators from the National Institute for Communicable Diseases (NICD) in Johannesburg and State Veterinary Services in Stellenbosch, this investigated transient and transgenic expression of soluble and membrane-bound forms and their immunogenicity, as well as a DNA vaccine consisting of the HA genes cloned into Tomas Hanke’s pTH vector.

The protein expression work was published in 2012, as well as being featured here in ViroBlogy at the time.

Image

What we had managed to show was that we could get excellent production of the H5 HA in both soluble and bound forms, and that especially the membrane-associated form of the protein was highly immunogenic, and elicited antibodies in experimental animals that were appropriately neutralising, indicating its suitability as a vaccine candidate.

Now this all happened despite our running out of money AND Liezl leaving to have a baby…and then we managed to get another paper out of the work, this time on the DNA vaccine side of things.

Image

We pitched this at the South African Journal of Science as a vindication of the faith in us by exclusively South African funding agencies – and managed to get the cover of the issue in which it appears, thanks to the truly excellent artwork of Russell Kightley from Canberra, Australia.  Front AND back covers, as it happens…!

Image

Image

And this all made Sandiswa Mbewana, who is now a PhD student on another project, very happy:

Image

This all came in excellent time to mark the establishment in the Department of Molecular and Cell Biology at the University of Cape Town, of a new URC Research Unit: namely, the Biopharming Research Unit (BRU).

BRU

Watch this space…B-)

Plant-Based Antibodies, Vaccines and Biologics 5, Part 5

3 September, 2013

Session 6:Vaccines II

This was SUPPOSED to open with a report from Medicago Inc, on ‘Developing plant-made influenza vaccines: From discovery to commercial scale production’  – but didn’t, because they were all shaken up (in a good way) by having been effectively bought by Mitsubishi Tanabe Pharma Corporation, and no-one came.

This is a success story in its own right, however, as their recent and highly successful activities in the areas of making influenza vaccines and human rotavirus VLP-based vaccines in plants marked them out as a target for acquisition by Big(gish) Pharma – for which we commend them.

It is sad, however, that their only presence at the conference was on the back of my windbreaker B-)

Konstantin Musiychuk (Fraunhofer USA) was the first up, then, speaking on ‘Preclinical evaluation of VLP-based malaria transmission blocking vaccine’.  He described how there are 3 types of intervention that may work with malaria: these are at the pre-erythrocytic, blood stage, and transmission blocking stages of infection.  Antibodies to Pfs48/45, Pfs230 proteins block the fertility of or destroy the macrogamete.  Pfs25 and 28 Abs block the ookinete to oocyst developmental phase; all potentially block transmission.  Accordingly, they expressed these as fusions with the alfalfa mosaic virus (AMV) CP with mutation(s) to prevent glycosylation.  The Pfs25 protein was the best candidate; they cloned a mutated version (glyc-), fused at the N-terminus to AMV CP, and expressed via their TMV-based “launch vector” after vacuum infiltration.  He noted that the fusions have full-length and proteolysed products – which is needed for VLP formation as native CP is needed to avoid steric hindrance in assembly.  They obtained nice particles as shown by EM, showing surface decoration.  Dynamic light scattering [Ed: must get me one of those…] results show a nice tight range of 17nm particles.

They used the products with/out Alhydrogel as adjuvant, IM in mice: they got good titres maintained >170 days, with  2x inoculation.  They diluted test sera with naive human serum and used this to membrane-feed mosquitoes, then after 1 week dissected them and assayed for parasites: oocyte counts in mid-gut reflected efficient blocking of acquisition.  The adjuvant+ doses worked well down to 0.1 ug (100%).  Single doses of 1, 5 or 25 worked 100% as well.  After 6 months, 5 and 25 ug doses still gave 90%+ blocking.

They made GMP lots, very pure:  2 doses at 0 and 21 days resulted in complete blocking down to 0.3 ug, with >99% blocking after 40+ days.  Tox studies were fine, although the  Alhydrogel apparently causes some side effects.   Scaleup from 1-50 kg showed no changes in the Ag.  The Phase 1 trial is expected in Q3 2013.

This was most impressive: it is to be hoped that the promise is maintained!

Yoseph Shaaltiel (Protalix Biotherapeutics, Israel) spoke on Protalix’s new product: this was alpha galactosidase-A, for the treatment of Fabry disease.  This is an X-linked lysosomal storage disease that results in massive storage of glycolipid Gb3, in cells, in the vascular system and elswhere, which impairs the tissue of the heart and affects kidney and other organ function.  There were worse consequences than with Gaucher disease, while it was less obvious.  The current therapy was seen as being bad, and patients had reduced life expectancy.  There were 2 therapeutic enzymes on the market: these were Agalsidase Alfa and Beta; these were very inefficient and expensive, so cost benefit was very limited.  1/2 life in blood was normally just a few minutes, and the proteins were very immunogenic.

Protalix aimed at making a biobetter: this was made in tobacco cells cultured in bags (they used Icon vectors, so could not work in their favoured carrot), by cocultivation with Agrobacterium and then killing the bacteria.  The protein subunits were PEGylated to reduce immunogenicity and x-linked using bis-NHS-PEG.  This gave improved stability, longer circulatory 1/2 life, enhanced activity in target organs with similar to improved kinetics, so lower dosing and longer intervals between doses were possible.  Yields were good too, and they could make the enzyme very pure.  The product had the same kinetics as the commercial products with better activity over a wide pH range.

As far as glycosylation was concerned, the commercial product had very complex glycosylation, while the plant-made product’s profile was very consistent and simple.  It had an enhanced circulatory 1/2 life, of 581 vs 13 min, and also had higher activity in target cells – heart, kidney – over time.  Yoseph noted that the  patents on the enzyme(s) were limited to CHO cell production, meaning they had a useful window to exploit.

A comment from Jim Carrick was that the FDA was not interested in PEGylated products, as this could lead to vacuolation of kidneys in the long term.  Yoseph said their product was not the same, as normally PEGylation added 20-40 kDa, whereas theirs was a much shorter x-linker.  Their product was, moreover, already in clinics, as the  FDA had said they should move straight to patients rather than testing it in healthy people.

Lydia Meador (Arizona State University) reported on their lab’s HIV vaccine candidate, made in plants and also vectored by NYVAC-KC delB19 poxvirus.  They had previously shown that a CTB-HIV membrane proximal region (MPR) fusion vaccine resulted in Ab that stops transcytosis of HIV by Ab; she noted that live vectors enhance T-cell responses compared to subunit vaccines, so a combination would be a good idea.

Accordingly, they had cleverly produced whole HIV Gag and a deconstructed gp41 – stable Gag transgenics, and transiently-produced dgp41 – in the same plants, to make 100nm VLPs.  While VLPs are highly immunogenic alone, they wanted to prime with the NYVAC and boost with plant-made antigen.  They obtained good p24 Ab responses with NYVAC and the VLP boost; gp41 less so.  In terms of mucosal immunity, they saw the IgA response against gp41 was significantly higher in the NYVAC+VLP combination, as were CD8+ T-cells.  She noted that the anti-NYVAC titre was high after 3x doses.  In response to my question, she did not know if the NYVAC vaccine made VLPs in mice – which it may not do, even if it works in plants, due to different protein requirements for budding in mouse vs plant cells.

Daniel Tusé (Intrucept Biomedicine, Kentucky) – a company founded with Kenneth Palmer – spoke on ‘Safety and efficacy of plant-produced Griffithsin for antiviral indications’.  He noted that while griffithsin was an excellent anti-HIV microbicide, it was also a reasonably broad-spectrum antiviral lectin, as it was effective against the recently-emerged MERS CoV and  influenza viruses.

The protein was hard to make from seaweed, and E coli was useless for production; however, they got g/kg in tobacco via conventional rTMV vectors, and now even better with Icon and Nomad vectors.  KBP had manufactured it to near-GMP production standards, again at g/kg yields, with product recovery at 30% from leaves and 50% from leaves + stems, to a final purity of 99.8%.  The potency was the same as the alga-derived product, and they had 100s of gm of product.

As griffithsin binds HIV with very high affinity, its primary use would be as a topical microbicide, to prevent transmission of HIV and HSV; to prevent coronavirus infections, and to act on chronic virus infections.  The protein is not mitogenic on PBMC and does not activate T cells; it does not produce inflammatory cytokines in human PBMC, unlike cyanovirin, which had a much worse proinflammatory profile.  The epithelial toxicity was also very low, which was in contrast to some well-publicised agents which had disastrously resulted in increases of HIV acquisition in women using them.

A carbopol-based gel was found to have the best drug-release kinetics, so was adopted for formulating the product for use.  This protects mice against genital herpes: herpes has 2x the risk of infection per exposure compared to HIV infection.  The gel has broad specific activity against coronaviruses too, to a wide spectrum of viruses from human, cow, chicken and pig.  It could protect mice against SARS CoV, if given intranasally at 2 doses/day.

The protein also has uses in prevention of infection in the organ transplant area, eg against hepatitis C virus (HCV): it prevents infection of Huh-7 cells by cell-culture derived HCV, and partially protects hepatocytes from viral spread in vivo.  If injected in animals it persists, and maintains an anti-HIV activity.  It is immunogenic, but only weakly so, and Ab to it don’t neutralize its effects.  Their lab was using rational design to take out T-cell epitopes without affecting antiviral activity.

Daniel stressed that this is a new drug, which can be preferentially be made in plants at high yield, with very low cost of goods; that it was effective and safe.

Hugh Haydon (KBP) mentioned that the cost of goods was “pennies/dose”.

Session 8:

This was an interactive discussion session, addressing the topic ‘Commercialisation of molecular pharming products – objectives and targets for the next 5 years’.

The panel: from left - Hugh Haydon, Kevin Whaley, John Butler, Scott Deeter, Einat Brill

The panel: from left – Hugh Haydon, Kevin Whaley, John Butler, Scott Deeter, Einat Brill

Hugh Haydon of Kentucky BioProcessing (KBP), , speaking on behalf of the new MAPP, KBP and Icon collaboration, addressed product selection.  He noted that MAPP was responsible for product development, Icon for technology development and purification, and KBP for large-scale manufacture.  They had spun out Solmab as a collaborative vehicle for production of MAbs for infectious disease therapy.

He described their product selection rationale: this was based on

  • proof of concept data
  • platform suitability
  • capacity for dual use of product
  • availability of capital
  • speed of the regulatory process
  • regulatory success rate
  • scalability of existing infrastructure

Accordingly, they had selected a “biobetter” of Synagis, and an Ebola MAb cocktail.  The Synagis equivalent was better due platform parameters, known clinical parameters, the fact there were established markets which can grow, government and NGO humanitarian interest, and potential adaptation to other viruses.  For Ebola, they had a 3 MAb cocktail that was known to work, strong government interest (for a stockpile), a more rapid regulatory pathway, and a tropical disease voucher from the FDA.  He pointed out that these products won’t make blockbuster status, but are appropriate for small companies like theirs.

Kevin Whaley (MAPP) spoke on how we needed therapeutics that were multipurpose (disease, indication) as well as multi-vaccines.  The attributes of the new biologics were multi-use, speed of production, scale of production, and cost advantage – especially for global health products costing <$US10/g, at scales of >10K kgs, with increased efficacy (pathology, cancer), increased acceptability and access.  He noted that all modern paediatric vaccines are multi – this saves visits to clinics, especially in developing countries.

Scott Deeter (InVitria) noted that the biologics market was edging up to being worth $US125 billion – and reckons progress with plant-produced products is excellent.

John Butler (Bayer) thinks we are still looking for suitable products!  He was of the opinion that initial targets were too difficult (eg NHL – and flu??!), and that improved product characteristics must benefit from being plant-made.  He was adamant that PMP must not compete on price with other platforms – because there was no such thing as a bottleneck in fermentation capacity world-wide, and established industry could just cut prices if they wanted to.  He spoke of real and perceived hurdles:

  • regulatory pathway isn’t a hurdle
  • plant vs human glycosylation is not either, as plant-specific glycans were not more immunogenic than human

Real risks were that:

  • there were well-established alternatives
  • the plant-made product industry was overstretched in terms of resources

Einat Brill (Protalix) addressed their future strategy:

  • new biologics for orphan indications (clinical trials were smaller, one needed only several 10s kg a year for an entire disease cohort)
  • recombinant vaccines
  • hard to express proteins that were best expressed in plants

ApApproved biologics:

  • Biobetters of commercial products
  • They would continue to establish PMP regulatory environment as a viable route for biologic drugs development
  • Biobetter efficacy: longer circulatory half life for favourable clinical outcome
  • regimen frequency: longer treatment intervals due to increased drug stability, with lower dosing
  • Changing administration route (eg: oral vs injectable): helps to improve patient compliance

This was an excellent session, if only to hear how people who have been involved in getting PMPs to the market viewed the prospects for the industry – and it appeared favourable, despite John Butler’s caveats.

Moratorium on using live rinderpest virus lifted for approved research

30 July, 2013

See on Scoop.itVirology News

Benefits of future research should be carefully balanced against potential risks

Paris, 10 July 2013 – A moratorium on using live rinderpest virus for approved research has been lifted by the Food and Agriculture Organization of the United Nations and the World Organisation for Animal Health (OIE).

The moratorium followed the adoption of a Resolution in May 2011 by all OIE Member Countries that urged members to forbid the manipulation of rinderpest virus containing material unless approved by the Veterinary Authority and by FAO and OIE.

The two organizations have now put in place strict criteria and procedures to follow in order to obtain official approval for any research proposals using rinderpest virus and rinderpest virus-containing materials. One of the most crucial requirements is that the research should have significant potential to improve food security by reducing the risk of a reoccurrence of the disease. This procedure replaces an earlier complete ban on handling the virus.

Rinderpest was formally declared eradicated in 2011, but stocks of rinderpest virus continue to exist in laboratories. In June 2012, a moratorium on handling the virus was imposed after an FAO-OIE survey found that the virus continues to be held in more than 40 laboratories worldwide, in some cases under inadequate levels of biosecurity and biosafety.

When rinderpest was officially eradicated, FAO and OIE member countries committed themselves to forbid the manipulation of rinderpest virus-containing material unless approved by the national veterinary authority as well as by FAO and OIE.

Paramyxovirus EM courtesy of Linda Stannard

Thanks to Len Bracher for alerting me to this.

Ed Rybicki‘s insight:

This is an interesting sequel to the eradication of wild rinderpest virus, which I have covered in some detail here on ViroBlogy: see here (http://rybicki.wordpress.com/2010/11/05/rinderpest-gone-but-not-forgotten-yet/) and here (http://rybicki.wordpress.com/2011/08/03/deliberate-extinction-now-for-number-3/).

The article covers an interesting prospect: that it may be possible to use attenuated, safe vaccines against the related peste des petits ruminants virus (PPRV) not only to protect against any resurgence of rinderpest, but also to eradicate this rather nasty virus.

Which is, apparently, spreading at rather an alarming rate, and is an obstacle to small ruminant production (http://www.fao.org/ag/againfo/resources/documents/AH/PPR_flyer.pdf).

So maybe this is “Now for Number 4!” time.

See on www.oie.int

Plant-Based Vaccines, Antibodies and Biologics 5: Part 1

27 June, 2013

Plant-Based Vaccines, Antibodies and Biologics: the 5th Conference

Verona, Italy, June 2013

The return of this biennial meeting to Verona – the third time it has been held here – was a welcome change; while the previous meeting in Porto in 2011 may have been good, the city was nothing like as pleasant a place to relax.  My group is now familiar enough with Verona that we know just where to go to get pasta by the riverside – or, on this occasion, “colt loin with braised onion and potatoes” and “stewed horse with red wine”.  Which seem more palatable, somehow, as “Costata di puledro con cipolle brasate e patate” and “Stracotto di cavallo speziata” respectively, but were enjoyed anyway.

The conference kicked off with an opening plenary session, chaired by the Local Organizing Chair, Mario Pezzotti, of the University of Verona.  The headline act was a talk on taliglucerase alfa – aka glucocerebrocidase, a Gaucher Disease therapeutic  –  by Einat Almon of Protalix Therapeutics from Carmiel, Israel.  I featured the product here last year, after an earlier feature here; suffice it to say that it has soared since FDA approval, and now Protalix is pushing hard with new plant-made products to follow it up.  While they use carrot cells for taliglucerase alfa, apparently they are using suspension-cultured tobacco cells for other products – and are using an easily-scalable disposable 800 litre plastic bag system, with air-driven mixing of cells suspended in very simple, completely mammal-derived product free media.  Hundreds of patients had been treated with the drug for up to 5 years with no ill effects, and the possibility of switching therapies from mammalian cell-made products to the plant cell-made had been successfully demonstrated.

Scott Deeter of Ventria Biosciences (Ft Collins, USA) spoke next, on “Commercializing plant-based therapeutics and bioreagents”.  His company has possibly the most pragmatic attitude to the production and sale of these substances that I have yet met, and he struck a number of chords with our thinking on the subject – which of course, post-dates theirs!  Ventria use self-pollinating transgenic cereals for production of seed containing the protein of interest, and rice in particular, for safety reasons – and because the processing of the seeds is very well understood, and the purification processes and schedules are common to many food products and so do not require new technology.  He reckoned that a company starting out in the business needed an approved product in order to give customers confidence – but should also engage in contract services and contract manufacture of client-driven products in order to avoid being a one-product shop.  To this end, they had received APHIS Biological Quality Manufacturing Systems (BQMS) certification (similar to ISO9001), with the help of the US Biotechnology Regulatory Services.

Their therapeutic products included diarrhoea, ulcerative colitis and osteoporosis therapeutics which were already in phase II clinical trial.  Scott noted that in particular, recombinant lactoferrin was a novel product, which could only feasibly be produced in the volumes and at the price required for effective therapy, by recombinant plant-based production systems.  It also filled a high unmet need as a therapy for antibiotic-associated diarrhoea in the US, with +/-3 million patients at risk annually who presently cost service providers over $1500 each for treatment.

A third commercialization option was bioreagents and industrial enzymes, which they marketed via a vehicle called InVitria: they had a number of products already in the market, which Scott claimed gave confidence to the market and to partners, while building capacity to make therapeutics.  Something that was particularly attractive to our prospects was that a collection or pool of small volume products – say $5-10 million each – gave a respectable portfolio.  He noted that Sigma Aldrich and Merck were already marketing their human serum albumin, which competed effectively with serum- and yeast-derived products.

George Lomonossoff from the John Innes Centre in Norwich, UK, spoke next on “Transient expression for the rapid production of virus-like particles in plants” – a subject close to our hearts, seeing as we have for the last five years been associated with George and partners in the Framework 7-funded PlaProVa consortium.  He mentioned as an object example the recent success in both production and an efficacy trial of complete Bluetongue virus (BTV) serotype 8 VLPs, made in Nicotiana benthamiana via transient expression using their proprietary Cowpea mosaic virus (CPMV) RNA2-derived pEAQ vector: this was published recently in Plant Biotechnology Journal.

Another very useful technology was the use of CPMV capsids as engineered nanoparticles: one can make empty VLPs of CPMV at high yield by co-expressing the coat protein (CP) precursor VP60 and the viral 24K protease: the particles are structurally very similar to virions in having a 0.85 nm pore at 5-fold rotational axes of symmetry, meaning they can be loaded with (for example) Co ions.  It is also possible to fuse targeting sequences – such as the familiar RGD loop – into the surface loops of the CPMV CPs, and to modify the inner surface too.  One application would be to engineer Cys residues exposed on the inside, which could bind Fe2+ ions: this would result in particles which could be targeted to cancer cells by specific sequences, then heated using magnetic fields.

John Butler of Bayer Innovation GmbH (Leverkusen, Germany) closed out the session with an account of lessons learned from the development of the plant-derived non-Hodgkins lymphoma (NHL) vaccine, that they had acquired with Icon Genetics, who in turn had inherited it from the sadly defunct Large Scale Biology Corp.  It was rather depressing to hear that Bayer had dumped the vaccine, despite the developers having reached their targets in turning 43 of 45 tumour samples into lifetime individualized supplies of vaccine within12 weeks, and despite the phase I trial being as successful as could be hoped.  To this end, the vaccines had been well tolerated and were immunogenic; of the patients who reacted immunologically, all but one were still tumour-free presently.

He felt that the problem was that NHL trials were too long and therefore too expensive as it was a slow-progressing disease; that a different clinical approach was needed, and that using the vaccines as a first-line therapy instead of only after the 2nd or 3rd relapse would be a much better idea.  The main lesson learned was that proving the technology would be far better done with a therapeutic vaccine for a fast-acting cancer, which would allow 1-2 year clinical trials with overall survival as an endpoint.

(more coming)

HPV vaccines for South Africa: coming to a school near you!

19 May, 2013

From The Independent Online:

HPV and cervical cancer: courtesy Russell Kightley Media

HPV and cervical cancer: courtesy Russell Kightley Media

“Cape Town – Government will start administering cervical cancer vaccines in schools from February next year, Health Minister Aaron Motsoaledi has announced.

Speaking during the health budget vote debate in the National Assembly on Wednesday, Motsoaledi said government hoped to negotiate lower prices for the vaccine, which treats the Human Papilloma Virus (HPV) – the major cause of cervical cancer among women.

Quoting experts, he said cervical cancer affected 6000 South African women a year, 80 percent of them black. More than half the women affected died of the disease.

While the HPV vaccine presented an opportunity to prevent women from contracting cancer, there were still obstacles to overcome.”

This is a really, really big deal for South Africans – and pity is, the vaccine will not be given to boys, or universally to girls.

Seriously: all the science says that giving it to boys as well limits spread of the viruses far better; not making it universally available will mean all sorts of recriminations around unequal access (read: to less privileged kids ONLY as part of the government programme at first).

But a big step in the right direction!

Vaccines: a simple message

28 February, 2013

+MaryMangan over there on Google+ made an interesting point about simple messages to refute the kinds of nonsense promulgated by vaccine denialists, among others.

Here’s my contribution:

Vaccines!

Vaccines!

ViroBlogy: 2012 in review

1 February, 2013

So: thank you, anyone who clicked in, and regular visitors.  You make it worthwhile!!

The WordPress.com stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

4,329 films were submitted to the 2012 Cannes Film Festival. This blog had 33,000 views in 2012. If each view were a film, this blog would power 8 Film Festivals

Click here to see the complete report.

Virus-like particle and Nano-particle vaccines 2012: a conference report

30 January, 2013

Alta van Zyl, Virology Group, Molecular & Cell Biology Department, UCT

Introduction:

VLP flusm

Haemagglutinin-only Influenza A virus VLP. Courtesy of Russell Kightley Media

The new international conference on virus-like particles and nano-particles (VLPNPV) took place in Cannes, France at The Novotel Montfleury Hotel from the 28th to the 30th of November 2012.  The scope of the conference included virus-like particles (VLPs), the plant-based expression of VLP vaccines as well as expression and optimisation of VLPs.

Other topics included in the conference were:

  • VLP platform delivery systems
  • VLP vaccines
  • Nano-particles and nano-particulate vaccines

A multitude of topics were covered during the conference and many of the talks pertained to the immunogenicity of the VLPs and nano-particles and how they compared with the immunogenicity of DNA or subunit vaccines.

Talks were given by researchers from companies such as Medicago, Mucosis, Pevion Vaccines and Novavax. These talks gave a perspective on factors that need to be considered when commercialising VLP/nano-particle vaccines and to be GMP compliant.

Compelling presentations:

Developing plant-made virus-like particle vaccine products: An integrated platform from discovery to commercial scale

Marc-Andre D’Aoust, Nathalie Landry, Sonia Trepanier, Michele Dargis, Manon Couture and Louis-Philippe Vezina (Medicago, Quebec City, Quebec, Canada)

This talk was about a plant-made VLP against both pandemic and seasonal influenza- these vaccines are now in the clinical trial phase. What was especially interesting was the view from an industry point of view where expression had to be scaled up to produce large amounts of vaccine.  The Medicago platform can synthesize and clone approximately 100 gene constructs in two weeks, they can prepare 100 bacterial cultures per week and they have automated infiltration where 200 plant transformations can be performed per day and 150 VLP engineering approaches can be tested in one week.  For influenza Medicago tested 48 different infiltration approaches in one day for HA, NA, M1, M2 as well as P1 Gag and HGalT.  Medicago has been able to produce 10 million doses of HA VLPs in just one month.

See also: 

  • D’Aoust et al (2010) PBJ 8:  607-619 – The production of hemagglutinin-based virus-like particles in plants: a rapid, efficient and safe response to pandemic influenza.
  • http://www.medicago.com

Development of RNA-free plant VLPs a source of novel therapeutics

George Lomonossoff (John Innes Centre, Norwich, UK)

This group made empty Cowpea Mosaic Virus (CPMV) VLPs that contained no RNA.  CPMV VLPs are versatile nanoparticles to which organic, inorganic and biological molecules can be bound.  The empty nature of the particle means that they can be used as carrier molecules for therapies; this could prove to be potentially useful as a cancer-treatment therapy.  The system is advantageous because of the lack of RNA which makes the particles non-infectious and no bio-containment is needed for the production of these VLPs.

Immunogenicity of VLPs: an immunological perspective

Martin Bachmann (University of Zurich, Zurich, Switzerland)

Background was given from immunological point of view about what makes VLPs so immunogenic. Three properties contribute to the immunological properties of VLPs (1) their size, (2) the repetitiveness of the particle capsid which provides multiple sites for antibody binding and (3) TLR ligands – the particle can be disassembled, the RNA removed and replaced with a TLR ligand to enhance immunogenicity. Also, the size of VLPs is optimal for drainage to the lymph nodes.

Immunogenicity optimization strategies for public-sector development of vaccines: the critical role of optimizing the antigen.

Martin Howell Friede (WHO, Geneva, Switzerland)

This talk was about looking at VLPs from the vaccine development view.  Monomeric antigens are not very immunogenic; therefore adjuvants were developed and came into use. For an efficient vaccine the antigen must be multimeric as antigen alone is insufficient to be immunogenic without adjuvant. Two factors have to be considered when producing a vaccine for FDA approval; (1) optimise the antigen before using an adjuvant, (2) use an adjuvant that has already been approved by the FDA. VLPs as vaccines provide the potential for immune-stimulation without the addition of adjuvant as the multimeric presentation of the antigen will enhance its immunogenicity.

Enhancing the immunogenicity of VLP vaccines

Richard W. Compans (Emory University, Atlanta, Georgia, USA)

This talk highlighted strategies which could be used to enhance the immunogenicity of VLPs.

  1. Look at alternate routes for vaccine delivery (intranasal, intramuscular, subcutaneous etc)
  2. Increase the breadth of immunity by enhancing responses to conserved antigens/epitopes
  3. Increase the amount of antigen incorporated into VLPs
  4. Incorporate the adjuvant into the VLPs as part of the structure

See also:

  • Ye et al (2011) PLoS One 6(5):  e14813
  • Wang et al (2008) J Virol

Innate and adaptive responses to plant-made VLP vaccines

Brian Ward (McGill University, Montreal, Quebec, Canada)

Brain Ward is also the medical officer at Medicago.  Humans rarely react to plant proteins/antigens. The plant glycans fucose/xylose at the N-terminal is an allergen and can cause anaphylaxis in humans. During trial experiments with influenza no individuals developed IgE responses to plant glycans, therefore plant produced vaccine is safe. The H1 VLP induced long lasting memory multifunctional T-cell responses in humans.

Impressions of the conference:

The conference was well organised with leaders in the field presenting their work. Interaction with the delegates aid in building crucial networking opportunities and work relationships. The international arena is packed with new technology development allowing us the opportunity to learn and improve our own understanding of various concepts.

This conference proved to be an invaluable learning experience and I thank the NRF for this opportunity and for providing me with the funding to attend this conference.  The exposure to conferences, especially those in the international arena, aid in the development of students and contribute to the quality of research that is conducted at UCT.

References:

1. VLPNPV website

(http://www.meetingsmanagement.co.uk/index.php?option=com_content&view=article&id=33&Itemid=83)

2.  Personal notes taken at the conference

Nonviral delivery of self-amplifying RNA vaccines – NOT!!

27 August, 2012

See on Scoop.itVirology and Bioinformatics from Virology.ca

“Despite more than two decades of research and development on nucleic acid vaccines, there is still no commercial product for human use. Taking advantage of the recent innovations in systemic delivery of short interfering RNA (siRNA) using lipid nanoparticles (LNPs), we developed a self-amplifying RNA vaccine. Here we show that nonviral delivery of a 9-kb self-amplifying RNA encapsulated within an LNP substantially increased immunogenicity compared with delivery of unformulated RNA. This unique vaccine technology was found to elicit broad, potent, and protective immune responses, that were comparable to a viral delivery technology, but without the inherent limitations of viral vectors. Given the many positive attributes of nucleic acid vaccines, our results suggest that a comprehensive evaluation of nonviral technologies to deliver self-amplifying RNA vaccines is warranted.”

 

I would re-ttitle this “Non-delivery of non-viral vectors…”.  Seriusly, folks, this is just the old Alphavax VEE vectors dressed up with with an in vitro synthesis step, and what amounts to a liposome delivery system.  Which means that it would be HIDEOUSLY expensive to produce, and is of no practical significance as a candidate vacine system whatsoever.

 

But I thank Alan Cann for pointing it out B-)

See on www.pnas.org

PLoS Pathogens: ADCC Develops Over Time during Persistent Infection with Live-Attenuated SIV and Is Associated with Complete Protection against SIVmac251 Challenge

24 August, 2012

See on Scoop.itVirology and Bioinformatics from Virology.ca

“Here we show that live-attenuated SIV induces progressive increases in ADCC over time, and that the development of these antibodies is dependent upon the persistent replication of the vaccine strain. In two different experiments, the animals immunized with live-attenuated SIV that remained uninfected after pathogenic SIV challenge had higher measures of ADCC than those that became infected. Our results suggest that antibodies contribute to protection by live-attenuated SIV, and that persistent stimulation of antibody responses may be essential for HIV-1 vaccines to induce high ADCC activity.”

 

Shit HOT results, in that they demonstrate that – as some have said repeated ly over years – that neutralising Ab are NOT necessarily the Holy Grail, and that ADCC and other mechanisms are also really important.  Good Stuff…B-)

See on www.plospathogens.org


Follow

Get every new post delivered to your Inbox.

Join 578 other followers