Archive for August, 2011

H5N1 just rolls on, and on, and on….

31 August, 2011

It is a very interesting phenomenon, in the annals of influenza viruses, that avian H5N1 just keeps rolling on, and on, and on.  It was already the longest-lasting and most serious animal pandemic several years ago, and has caused immense economic damage.  And now – it seems to just get worse.  From Vaccine Nation:

H5N1 kills up to 60% of the people it infects. It has resurfaced in recent months, most notably in Cambodia where it has infected eight people this year, killing all of them.

Reuters report that the call came after the U.N. Food and Agriculture Organization (FAO) warned on Monday of a possible resurgence of bird flu and said a mutant strain of the H5N1 was spreading in Asia and beyond.

While scientists are uncertain if this new strain — called H5N1-2.3.2.1 — is more virulent in people, they said it was different enough from its predecessor to escape a human H5N1 vaccine that can tackle the parent strain.

recombining flu viruses

I have blogged a lot on influenza viruses and their vaccines – search this site via the facility to your right! – and I can only reiterate what I have said a few times already: we really, really need to have some way of rapidly responding to emerging flu viruses, including new and nasty variants of H5N1.

And a very good way of doing that, given a VERY low barrier to entry in terms of manufacturing cost compared to conventional vaccines, is via plants.  Several companies, including Medicago Inc, have embraced the use of transient expression in plants as a means of rapidly producing both seasonal and pandemic flu vaccines – and I will blog on that technology soon.

Meantime, let’s just hope the new technologies can keep pace with the evolution of the viruses they are aimed at combatting.  And that someone will actually fund us to do something for our country!

 

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Vaccines are safe: now use them!

30 August, 2011

At last, someone heavy has gone and nailed it down: The Scientist (http://the-scientist.com/2011/08/26/vaccines-are-safe/) reports that

“Vaccines are safe and not the cause of autism, according to a new report from the Institute of Medicine, the health arm of the National Academies.  The panel based its conclusions on the review of more than 1,000 studies on eight vaccines commonly given to children, including those for chickenpox, meningitis, tetanus, and measles, mumps, and rubella (MMR).”

One.  Thousand.  Studies.  At least!  There’s more:

“Some serious side effects were linked to vaccines, but occurred very rarely. Among them: those who receive the chicken pox vaccine could later come down with pneumonia or meningitis if their immune systems become compromised by diseases such as cancer, and the MMR vaccine occasionally sets off brain inflammation or seizures, Nature reports. Six of the eight vaccines can also cause allergic reactions. The more serious side effects most commonly occur in children who have underlying immune problems.”

As I taught my captive second- and third-years for close on thirty years, there’s a risk-benefit calculation to be done for every vaccine, and indeed, for every drug that you or yours may be exposed to.  If there’s no benefit – because there’s no risk – then do without.  If, on the other hand, your baby stands a reasonable chance of getting seriously ill, and maybe even suffering permanent damage from getting infected by a preventable dissease – vaccinate!

And that’s rotavirus I’m talking about, not even something really nasty like measles.  I did the same survey over several years, asking 70+ students if they would give kids a vaccine that had a POSSIBLE 1/40 000 chance of causing a possibly fatal intestinal complication (intussusseption, or telescoping of the bowel) in (a) an environment where no children died of rotavirus, (b) an environment like in many places in the developing world, where 1/100 children might die.  Nearly every single one, every time, would not use it in (a), but would have no hesitation in scenario (b).

Regulars on this blog will know what I think about not vaccinating against measles.  So now, folks: reach out to a relative or a friend who espouses this utter nonsense linking vaccines to autism – and smack them solidly.  Then get their kids vaccinated.

OK, maybe not – but remonstrate with them, point them towards the evidence, tell them just how nasty some of the preventable diseases can be, and that they should realise measles, polio or rotavirus are only someone else’s plane trip away.

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A recycled virus to protect against TB?

25 August, 2011

News from the University of Cape Town site:

“UCT is taking part in the Phase IIb proof-of-concept efficacy trial of a candidate tuberculosis vaccine, a study that will involve people living with the human immunodeficiency virus (HIV).

Researchers from the Institute of Infectious Disease and Molecular Medicine will screen and test patients living in Khayelitsha, using the vaccine known as MVA85A. The patients are HIV positive but have not been infected with TB.

This is the first proof-of-concept efficacy trial in people infected with HIV using MVA85A, which is being developed by the Oxford-Emergent Tuberculosis Consortium (OETC), a joint venture between the University of Oxford and Emergent BioSolutions, and Aeras, a non-profit partnership focusing on TB vaccine regimens.

The MVA85A vaccine candidate is intended to boost the response of immune-essential T-cells already stimulated by the Bacille Calmette-Guerin (BCG) vaccine, also used against tuberculosis.”

So – fantastic, and it involves the alma mater, but what does it have to do with viruses??  Note the throwaway “…using MVA85A…”: while this could be an adjuvant, or some kind of carrier, it is in fact a live virus.  Modified Vaccinia Ankara, in fact, meaning it is a variant of the tried-and-true smallpox virus vaccines that have been with us since Edward Jenner did his thing on the 14th of  May, 1796.  Poxviruses, and especially vaccinia and fowlpox viruses, can also be genetically engineered to express foreign proteins, because they have large genomes and can tolerate even quite large insertions without it affecting the virus much.  There is a useful recent paper on the subject in PLoS One; inevitably, Wikipedia  has an article on it too.  Not a very good one, however!

It does have this, though:

“Modified Vaccinia Ankara (MVA) virus, is a highly attenuated strain of vaccinia virus that was developed towards the end of the campaign for the eradication of smallpox by Professor Anton Mayr in Germany. Produced by hundreds of passages of vaccinia virus in chicken cells, MVA has lost about 10% of the vaccinia genome and with it the ability to replicate efficiently in primate cells”.

So, two important features:

  1. the virus replicates in chicken cells and in chicken eggs, meaning it can be cultivated at large scale
  2. it does not replicate in primate, and in fact not in most mammal, cells

It does, however, undergo a significant portion of the life cycle in mammalian cells – only virion maturation does not occur.  This means that genes inserted into the MVA virus genome with appropriate poxvirus promoters may be expressed in cells containing virus particles even if the virus does not multiply.  The other Wikipedia page mentioning it – the Vaccinia page – has this:

“Modified vaccinia Ankara: a highly attenuated (not virulent) strain created by passaging vaccinia virus several hundred times in chicken embryo fibroblasts. Unlike some other vaccinia strains it does not make immunodeficient mice sick and therefore may be safer to use in humans who have weaker immune systems due to being very young, very old, having HIV/AIDS, etc.”

And THAT’S why MVA as a TB vaccine vector in what amounts to a high-risk environment for HIV infection in South Africa: because the vaccine won’t cause complications in immune-suppressed individuals.

As I have previously discussed here, MVA has also been used as a vector for a component of the South African HIV-1 vaccine developed at UCT that is currently in Phase I clinical trial in SA and in the USA: there the MVA was engineered to express both a gp150 Env and a polygenic fusion protein GRTTN (Gag-RT-Tat-Nef), and was the boost component to a dual-component DNA vaccine expressing both singly.

It is encouraging that technology that has been touted for many years is finally seeing the mainstream: a large clinical trial combining immunogenicity with efficacy.  Malaria antigens are also being delivered by MVA in clinical trials; HIV Env antigens were delivered using avian poxviruses in the only HIV vaccine efficacy trial that showed any positive effects at all – so the promise is finally being fulfilled.

A sword turned into a ploughshare.  We need to see more of them!

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Rating blogs for assessment purposes

12 August, 2011

Seeing as I was talking with colleagues in the world outside Virology (yes, I do have them) (yes, there is one!) about how one could get assessed in the academic environment for activities like blogging, it was quite heartening to get an email from one Tracy Myers, about this blog featuring in the “OnlineMastersDegrees.net’s list of the Top 50 Blogs about Biology“.

Not in the top 5, I discover, but hey, top 50 in a big class is OK…B-)

But we are distracted from the theme: how does one get material such as I produce in this blog, assessed in the obsessively publication metric-conscious University environment?

With difficulty, it would appear: AJC, I would like your opinion on this!  Access stats are one way, and I have used WordPress’s rather nice summary table for access over the life of this blog to demonstrate that (1) people do actually get to it, and in quite significant numbers, (2) they come from all over the world.  And I would especially like to thank our Saudi Arabian Virology student readers at this juncture!

It’s something the powers-that-be at Unis are going to have to get their heads around – because it’s an increasing trend for academics to blog, and for their students to read said blogs, and to be influenced (hopefully positively) by them.

But I’ll just cherish my badge for a while…B-)  Thanks Tracy!

OnlineMastersDegrees.net

Best Blog Badge
 

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Deliberate extinction: now for Number 3

3 August, 2011

I have written previously about the Rinderpest virus eradication campaign – and now it appears as though the final nail has in fact been hammered into the coffin’s lid while I wasn’t looking.  I thank my son Steven for noticing!

It was officially announced on 26th June, in Rome – the headquarters of the Food and Agriculture Organisation (FAO) – that “…for only the second time in history, a disease has been wiped off the face of the earth”.

From a New York Times article:

The long but little-known campaign to conquer rinderpest is a tribute to the skill and bravery of “big animal” veterinarians, who fought the disease in remote and sometimes war-torn areas — across arid stretches of Africa bigger than Europe, in the Arabian desert and on the Mongolian steppes.

…
The victory is also proof that the conquest of smallpox was not just an unrepeatable fluke, a golden medical moment that will never be seen again. Since it was declared eradicated in 1980, several other diseases — like polio, Guinea worm, river blindness, elephantiasis, measles and iodine deficiency — have frustrated intensive, costly efforts to do the same to them. The eradication of rinderpest shows what can be done when field commanders combine scientific advances and new tactics.

… The modern eradication campaign began in 1945, when the Food and Agriculture Organization was founded. But it became feasible only as vaccines improved. An 1893 version made from the bile of convalescent animals was replaced by vaccines grown in goats and rabbits and finally in laboratory cell lines; a heat-stable version was developed in the 1980s.

The interesting thing about Rinderpest virus is that it is probably a consequence of human’s development of agriculture and especially the keeping of livestock, that got it into animals in the first place: it is closely enough related to measles virus that it probably only diverged from it some time around CE 1000.

So it’s not just us that get animal viruses – our pets and our livestock can get them from us, too.

But it’s now time to concentrate on the next two: polioviruses and measles.  Vaccinate, brothers and sisters, vaccinate!!

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Posted in Evolution, General Virology, Viruses | 2 Comments »