Posts Tagged ‘vaccine’

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Bird Flu Vaccine Launched – But For Whom?

22 May, 2008

The online 20 May issue of Nature News trumpets the release and marketing of a new H5N1 bird flu vaccine: GlaxoSmithKline’s Prepandrix has just been approved by the European Commission. 

Published online 20 May 2008 | Nature | doi:10.1038/news.2008.844

Bird flu vaccine to hit the shelves

Europe approves pandemic vaccine; countries must decide own strategies.

Tony Scully

The European Commission has approved a new vaccine against the H5N1 bird flu virus — the first vaccine designed to ward off a future pandemic. But how the drug, called Prepandrix, will be deployed by national governments remains unclear.The vaccine, produced by the UK drug giant GlaxoSmithKline, is aimed at the H5N1 strain currently circulating in birds as epidemiologists think that this is the most likely strain to cause a human pandemic. H5N1, which originated in south-east Asia and is carried by migrating birds and domestic poultry, has caused 382 human cases and 241 deaths worldwide since 2003.

Prepandrix targets an antigen from an H5N1 strain called A/Vietnam/1194/04, which has been detected in birds in Asia, Europe and Africa. Clinical tests have shown that the vaccine is also effective against other closely related variants of H5N1, such as H5N2. The release of the vaccine is seen as a gamble that any future pandemic strain will closely resemble the Vietnamese version used to derive the vaccine.

The article goes on to describe how “The first orders for Prepandrix were placed last year by Finland and Switzerland, before it had been approved by the European Commission. In 2007, sales for Prepandrix totalled US$284 million worldwide….”

Yes.  Well.  Um.  Where is the pandemic going to hit first?  Finland?  Switzerland?  I doubt it.  How about Indonesia, Thailand, Vietnam, Turkey, Egypt…or, horror of horrors, India or China?  All the places which will need a LOT of doses, cheap.

Do they stand any chance of getting them?  Not unless they have preordered.  And not – in the case a pandemic strikes – unless they are willing to take military action to prise their stocks out of the hands of the governments in the developed countries where the vaccines are made.

A senior WHO official stated the case very succinctly, at the Virus Africa virology conference in Cape Town in November 2005: “You people in the developing countries will be on your own if the pandemic comes.  You need to make your own vaccine…”.

We wait in hope.

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Posted in Influenza viruses, Vaccines: General | 6 Comments »

Influenza vaccines from plants??

22 April, 2008

I should have known Alan Cann would find this one; it’s just too good to miss – so I am going to add to what he said, as a way of further exploring what they could/should have done, as a result of discussions in our Journal Club this morning.

Alan wrote:

Influenza vaccines from plants

Posted by ajcann on April 16, 2008

 Our major defense against infection with influenza viruses is immunization of individuals with an annually updated vaccine that is currently produced in chicken eggs, with a global annual capacity of about 400 million doses, a scale of production insufficient to combat a pandemic. Furthermore, at least six months is required between the identification of new virus strains to be included in the vaccine formulation and the manufacture of bulk quantities. Uncertainties over the robustness of egg-based vaccine production are intensified even further by the emergence of H5N1 strains that are highly virulent to both chickens and eggs. There is a need to develop alternative vaccine production systems capable of rapid turnaround and high capacity. Recombinant subunit vaccines should circumvent some of the concerns regarding our current dependence on egg-based production.This paper reports on the production and evaluation of domains of influenza haemagglutinin (HA) and neuraminidase (NA) fused to the thermostable enzyme lichenase. All vaccine targets were produced using a plant-based transient expression system (Nicotiana). When tested in ferrets, vaccine candidates containing these engineered plant-produced influenza HA and NA antigens were highly immunogenic, and were protective against infection following challenge with homologous influenza virus. This plant-based production system offers safety and capacity advantages, which taken together with the protective efficacy data reported, demonstrates the promise of this approach for subunit influenza vaccine development.

A plant-produced influenza subunit vaccine protects ferrets against virus challenge
Influenza and Other Respiratory Viruses 2008 2: 33–40

There are a couple of interesting features of this paper, chief among them being the complete obscurity of the reasons why they use lichenase fusions, and what exactly their “launch vector” – which is what they use to express their proteins transiently – is.  Because the reference they give is incorrect – it is to a journal they erroneously call “Influenza”, which is not listed by PubMed, and turns out to be Influenza and Other Respiratory Viruses in fact – and is unavailable at our institution.  I am assuming, given the system uses a CaMV 35S promoter to drive RNA production, and they talk of “viral replication and target sequence expression from the [TMV] CP subgenomic mRNA promoter”, that the vector is a TMV-based replicon.  I was alerted by colleagues at the Journal Club to the fact that the same group used the same system – pBID4 “launch vector”, fusions to lichenase – for production of a HPV E7 vaccine in plants.  And referred to the same paper as this one does, for the vector and constructs.   Aargh!  I still don’t know why lichenase fusions are such a good idea!! 

A hint is given in the E7 paper: they say that “…these LicKM fusion proteins alone are able to activate both innate and adaptive antigen-specific immune responses”.  But they found in the paper under discussion here that alum was needed to get the best response…and they got the best yield AND immunogenicity out of their NA protein, which was expressed as a (presumably) soluble truncated native protein.  So the reason is still obscure.

The purification section of this paper is also woefully inadequate: saying “…recombinant antigens were enriched by ammonium sulphate precipitation followed by immobilised metal affinity chromatography and anion exchange chromatography, with dialysis after each step, to at least 80% purity” is NOT a method!  It is an anecdote, fit for a 1-minute talk maybe, but NOT for the Methods section of a paper.  Naughty, naughty!

Another interesting thing is the complexity of the vaccine constructs – again, exactly the same type of constructs as made for HPV E7; assembly-line vaccine producers, these guys!  These consist of the Gene of Choice (GoC) with a poly-His tag AND a KDEL (ER retention) tag at the C-terminus, AND the signal sequence of Nicotiana tabacum PR1a protein at their N-terminus.  This means (a) proteins get into the ER lumen, (b) get retained in the ER, (c) can be purified by Ni or other metal affinity column.  In addition to being fused to LickM.  Granted, the PR1 signal sequence is lost and the His tags can be removed – but the proteins still have significant “other” constituents – which is rather frowned on in a vaccine intended for humans.

I am also interested that they did not do the standard thing with their plant-produced HA GD protein and test for haemagglutination / RBC binding: this was in any case superseded by the fact that the vaccines were protective and antisera elicited by them worked in HI [haemagglutination-inhibition] assays, but it has long been regarded as a necessary first step.  I like these guys’ approach: forget the biochemistry; let’s see if it works!

All in all, a good paper despite our criticisms, which points up the very distinct possibility of being able to use plant production of influenza virus antigens for the rapid production of effective vaccines.

But I wish they’d included some more details….

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Posted in Influenza viruses, Vaccines: General | 4 Comments »

So there IS light at the end of the tunnel

1 April, 2008

After the shock of the second failure of an HIV-1 vaccine in Phase III trials recently – detailed to some extent here – we were surely due some relief.

And it is here: William Borkowsky and team have just published in AIDS and Human Retroviruses a paper which describes what amounts to successful “autologous immunisation” of a paediatric HIV-infected cohort by a series of progressively longer treatment interruptions, or drug holidays. 

The children, who ranged in age from 4 to 19, were all on HAART or highly active anti-retroviral drug therapy, and all had initially undetectable viral loads.  The subjects in the experimental arm of the trial were given a series of drug holidays of progressively increasing length over up to 17 cycles of treatment in some cases.  In the words of the authors:

“Increased HIV-specific immune responses and decreased HIV RNA were seen in those children who have had >10 cycles of antiretroviral discontinuations of increasing durations acting as autologous virus vaccinations. Other studies may have failed due to an insufficient number of exposures to HIV; most of the studies had fewer than six drug interruptions.”

This is a quite momentous finding: given that it is known that increased CD8+ T-cell responses to Gag proteins of HIV are correlated with decreased viral load in infected patients, this means that many times-repeated exposures of immunocompetent people to live virus seems to successfully elicit suitable immunity and reduce viral load, just as a vaccine could be wished to do.

But in all the vaccine trials, and in previous treatment interruption trials, no more than 4 vaccinations or 6 drug interruptions were performed – which may mean, given the lack of persistence of T-cell as compared to antibody responses, that simply too few treatments have been given in the past.

So is the solution to dose people considerably more often in prophylactic vaccine trials aimed at protecting against HIV infection? 

And possibly with subunit vaccines (such as our recent offering…B-) or killed whole-virus vaccines instead of “genetic vaccines” such as the DNA and virus-vectored HIV gene vaccines which have been so popular up to now?

We need to explore these possibilities – and to explore them soon.  There is a lot riding on the outcome….

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Posted in HIV, Vaccines: General | Leave a Comment »

MicrobiologyBytes Archive

14 December, 2007

Before I established this site, I posted a number of guest blogs to do with viruses on Alan Cann’s very wonderful MicrobiologyBytes site. Here are links to all the virus-related ones.

Maybe Not Quite The End

Posted on January 15, 2008
Review of a paper describing the receptor for the H5N1 HA protein

Given the current scare over H5N1 influenza virus in swans in the UK, it is possibly timely to recall that I wrote a little while ago in MicrobiologyBytes about how easy it appeared to be for […]

Bandicoot Blues

Posted on November 30, 2007
Description of a unique newly-described virus that looks like a chimaera of a papillomavirus and a polyomavirus

Now that the dust has begun to settle after the launch of Merck’s much-hyped Gardasil genital papillomavirus vaccine – discussed in MicrobiologyBytes here and here – people are turning again to looking at the natural history […]

Hurting rather than helping?

Posted on November 21, 2007
Some news on the failure of the Merck Adenovirus 5-vectored HIV vaccine

It should not have escaped the eye of the interested bystander that there has been a most unfortunate and premature end to a HIV vaccine trial recently – and that something that had been tested as […]

A Deeper Meaning

Posted on November 10, 2007
Some microbiology-related poetry….

I inadvertently became a published literary critic a little while ago. A long-time English Department colleague asked me for some help interpreting the collected works of possibly the most important modern poet from South Africa, and […]

Don’t look now, they’re in your genes

Posted on September 14, 2007
Description of natural insertions of virus gene fragments into a variety of organisms and how they elicit pathogen-derived resistance

And they’re protecting you! If you’re an insect, that is. Or possibly a plant.
In a remarkable convergence of news, an Israeli group led by Ilan Sela described how Israeli acute paralysis virus, which is implicated in […]

To bee or not to bee

Posted on September 11, 2007
News of how a single virus is suspected in the causation of “colony collapse disorder” of bee hives in the USA

A major recent mystery in US agriculture has been the phenomenon of “colony collapse disorder” (CCD) in honey bees. […]

This is the End

Posted on August 29, 2007
H5N1 highly pathogenic avian influenza virus mutates…

This is the End. Or the beginning of the end. Or possibly, the end of the beginning?
To misquote the immortal Bill Shankly: “It’s not a matter of life and death: it’s much more important than that”.
Having […]

Rolling down the road

Posted on August 27, 2007
Musings on rolling circle replication in viruses

In my idle moments (alas, too few these days!) I often try to think up lists of rock songs with a virus theme: you know, like “Cucumo” by the Beech Boys… “I got them ol’ burnin’, […]

Rooting the tree

Posted on August 3, 2007
News on inferring “ancestor sequences” for HIV to help make broadly effective vaccines

While fossilized viruses have never been found, we can often infer probable lines of evolutionary descent by analysis of extant genomic sequences. This sort of molecular phylogenetic approach has thrown up all sorts of interesting […]

It’s Life, Jim, but not as we know it…

Posted on July 24, 2007
Exploring what it means to be “alive”

Which could well apply to viruses, my very own favourite organisms – after all, they don’t respire, grow, excrete or any of those other good things […]

A feeling for the molechism*

Posted on June 26, 2007
Musings on what viruses are.

I think it’s permissible, after working on your favourite virus for over 20 years, to develop some sort of feeling for it: you know, the kind of insight that isn’t […]

Plus ça change, plus c’est … le same Web, only better?

Posted on June 8, 2007
A personal history of teaching Virology via the Web.

My, how things do change… I found myself reflecting, while I was looking over the detritus on our Web server of some 13 years of posting pages on the Web. “Orphan” pages, unconnected […]

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