Posts Tagged ‘Influenza’

Pandemic 2009 H1N1 vaccination produces antibodies against multiple flu strains

27 May, 2012

See on Scoop.itVirology News

“The pandemic 2009 H1N1 vaccine can generate antibodies in vaccinated individuals not only against the H1N1 virus, but also against other influenza virus strains including H5N1 and H3N2.”


And a possible reason for this could be that the H1N1pdm virus’ haemagglutinin is a natural “ancestral” sequence – the kind that HIV vaccine researchers are looking for for gp120/160, which have been shown to elicit a wider spectrum of cross-reacting antibodies than “evolved” proteins, or ones that have been selected for antigenic escape in humans for a good few viral generations.


Flu vaccine graphic by Russell Kightley Media

See on

Setting up a platform for plant-based influenza virus vaccine production in South Africa

5 May, 2012

A virus-like particle formed by influenza virus haemagglutinin budding out of plant cells. By Russell Kightley Media

See it also on Scoop.itVirology News

Our (very) recently-published article on plant-made flu vaccines in BMC Biotechnology:

Setting up a platform for plant-based influenza virus vaccine production in South Africa

Elizabeth Mortimer, James M Maclean, Sandiswa Mbewana, Amelia Buys, Anna-Lise Williamson, Inga I Hitzeroth and Edward P Rybicki

During a global influenza pandemic, the vaccine requirements of developing countries can surpass their supply capabilities, if these exist at all, compelling them to rely on developed countries for stocks that may not be available in time. There is thus a need for developing countries in general to produce their own pandemic and possibly seasonal influenza vaccines. Here we describe the development of a plant-based platform for producing influenza vaccines locally, in South Africa. Plant-produced influenza vaccine candidates are quicker to develop and potentially cheaper than egg-produced influenza vaccines, and their production can be rapidly upscaled. In this study, we investigated the feasibility of producing a vaccine to the highly pathogenic avian influenza A subtype H5N1 virus, the most generally virulent influenza virus identified to date. Two variants of the haemagglutinin (HA) surface glycoprotein gene were synthesised for optimum expression in plants: these were the full-length HA gene (H5) and a truncated form lacking the transmembrane domain (H5tr). The genes were cloned into a panel of Agrobacterium tumefaciens binary plant expression vectors in order to test HA accumulation in different cell compartments. The constructs were transiently expressed in tobacco by means of agroinfiltration. Stable transgenic tobacco plants were also generated to provide seed for stable storage of the material as a pre-pandemic strategy.

For both transient and transgenic expression systems the highest accumulation of full-length H5 protein occurred in the apoplastic spaces, while the highest accumulation of H5tr was in the endoplasmic reticulum. The H5 proteins were produced at relatively high concentrations in both systems. Following partial purification, haemagglutination and haemagglutination inhibition tests indicated that the conformation of the plant-produced HA variants was correct and the proteins were functional. The immunisation of chickens and mice with the candidate vaccines elicited HA-specific antibody responses.

We managed, after synthesis of two versions of a single gene, to produce by transient and transgenic expression in plants, two variants of a highly pathogenic avian influenza virus HA protein which could have vaccine potential. This is a proof of principle of the potential of plant-produced influenza vaccines as a feasible pandemic response strategy for South Africa and other developing countries.”

I have mentioned time and again that going green is the sensible thing to do: here is a concrete example of how my research group is trying to go about it.  This is a very sensible technology for rapid-response vaccine production, and especially for emerging or orphan or pandemic virus threats.  We got really good expresion levels of H5N1 HA protein via transient expression in plants, and have already started on pandemic H1N1 HA expression.  Let’s hope some governmental types in SA take some notice!

I thank Russell Kightley Media for the specially-commissioned graphic of budded HA-only VLPs.


Engineered H5N1: the wheels grind on, and on, and on….

19 April, 2012

The Scientist has a nice collection of articles on this topic, which I have commented on all over the place, so I though I might consolidate some of it in one place.

In response to the article entitled “Deliberating Over Danger“, I wrote the following:

The point I and others have made before is that H5N1 and other influenza viruses are not waiting for us to let engineered versions loose, before they cause pandemics: all of the mutations noted by the Fouchier and Kawaoka groups are almost certainly present in the several environments where H5N1 viruses are now endemic – and all it takes for all of them to be present together is a little more mixing.

Don’t discount other flu subtypes, either: while everyone is obsessing about H5N1, H3N2 is busy popping out of pigs in the USA; H9N2 in birds in Bangladesh; H5N2 in ostriches in South Africa – and all it would take is one or a couple of fortuitous reassortments, and a whole new flu virus could be unleashed.

While the “deadly” H5N1s are being worked on in lockdown facilities.

If we don’t know what the virus does, we won’t know what it can do. If we don’t know what to look for, we may be taken unawares, when the next 1918-type pandemic strikes.

I want to have universal flu vaccines by then – so we won’t HAVE to worry about a new flu


There are also three newer articles covering the controversy: these are

  • H5N1 Researcher to Defy Dutch Gov’t?
  • (with my comment – “Export permit to publish something?  Really?  A complete misapplication of laws to material that should not be subject to them.”)
  • White House Weighs in on H5N1
  • Flu Review Criticized
  • (with my comment – “So after a full and frank hearing did not go his way, after changes had been made to the paper in question (Fouchier’s), Osterholm complains.  Such is life….”

There is the slightly older article – “Bird Flu Papers to Publish” – describing the reversal of the NSABB’s decision to ask for redaction of the two papers describing mammal-to-mammal aerosol-transmissible H5N1.

An interesting article also describes Yoshihiro Kawaoka’s results:

“First, he introduced two mutations—N224K and Q226L—into the haemagglutinin (HA) protein of H5N1 that made the virus capable of sticking to receptors on human tracheal cells. Then he created a chimeric virus by combining the mutated HA protein with genes from the H1N1 virus, which sparked a pandemic in 2009. Kawaoka identified another HA mutation, called N158D, that allowed the virus to spread between ferrets that were not in direct physical contact. A fourth mutation, T318I, also showed up in the H5N1 strain, but its role in making the virus more transmissible among mammals is less clear.”

So there you are: an actual recipe for aerosol-transmissible H5N1.  It was always going to come out somehow, and now these two papers will probably the most cited flu papers ever.  Nothing like a little hype!  Meanwhile, H5 and its brothers and sisters are out there mutating away, with no help needed from anyone.  Roll on universal flu vaccines!!

A life in Virology

15 February, 2012

With a group of my UCT Medical School colleagues, I have been attending reasonably regular informal talks by Professor Keith Dumbell, formerly of St Mary’s Hospital, London, the University of Liverpool, and UCT.

Keith is a poxvirus expert, and was involved in the eradication of smallpox. He has also lived through several eras of modern virology, starting in 1945 in the pre-DNA and electron microscope days, through the advent of tissue culturing viruses, to the application of recombinant DNA techniques to viruses – and has a treasure trove of fascinating stories he is sharing with us.

Mostly about viruses, but occasionally about the characters involved as well. And the fact that any virologist worth their salt in the 1950s had to have skills in cutting sections, culturing viruses in eggs, centrifugation techniques, and keeping a veritable zoo of small animals.

I hope to get his permission to release a DVD of his reminiscences some day. Virology News

11 February, 2012

This is just to announce that I will be regularly posting “Virology News” updates on a new site I have just set up – as well as occasionally updating another site – “Virology and Bioinformatics from” – which is curated by Chris Upton, of Univ Victoria in Canada.

Even more ways to get your daily viral fix…B-)

And while they were arguing about killer H5N1…

8 February, 2012

…Elsevier’s Virology was calmly publishing another paper on a “mutant” H5N1….

The abstract:

Acquisition of α2-6 sialoside receptor specificity by α2-3 specific highly-pathogenic avian influenza viruses (H5N1) is thought to be a prerequisite for efficient transmission in humans. By in vitro selection for binding α2-6 sialosides, we identified four variant viruses with amino acid substitutions in the hemagglutinin (S227N, D187G, E190G, and Q196R) that revealed modestly increased α2-6 and minimally decreased α2-3 binding by glycan array analysis. However, a mutant virus combining Q196R with mutations from previous pandemic viruses (Q226L and G228S) revealed predominantly α2-6 binding. Unlike the wild type H5N1, this mutant virus was transmitted by direct contact in the ferret model although not by airborne respiratory droplets. However, a reassortant virus with the mutant hemagglutinin, a human N2 neuraminidase and internal genes from an H5N1 virus was partially transmitted via respiratory droplets. The complex changes required for airborne transmissibility in ferrets suggest that extensive evolution is needed for H5N1 transmissibility in humans. [my emphasis – Ed]

I have covered the use of glycan arrays to characterise influenza viruses’ binding specificity previously; I thought then, and do now, that it is a very cool technology – and one that has shown in this case that H5N1 variants can be selected from an originally “wild” population, that preferentially bind the human-type receptor.

And they did it like this:

To examine the functional evolution of H5 HA receptor specificity in the laboratory, we implemented an in vitro receptor-binding virus enrichment approach that recapitulates in vivo selection. Synthetic 6′-sialyl (N-acetyl-lactosamine) (6′ SLN) was used as the affinity ligand mimicking the human receptor to capture spontaneous viral receptor variants on the surface of magnetic beads. Starting with a pool of 108 EID50 of A/Vietnam/1203/2004 (VN04 virus), we performed four consecutive rounds of in vitro binding and elution followed by isolation of 150 individual virus clones by plaque purification and characterization by sequence analysis.

No “genetic engineering” here – or furore over “killer viruses escaping the lab!”  Possibly because (a) “mutant virus was transmitted by direct contact in the ferret model although not by airborne respiratory droplets”, and (b) “a reassortant virus with the mutant hemagglutinin, a human N2 neuraminidase and internal genes from an H5N1 virus was partially transmitted via respiratory droplets” [my emphasis].

Meaning they didn’t actually make anything that could immediately elicit such scare-mongering as the more notorious studies I and many others have reported on previously.

However, the grim NSABB folk were quick to decry the publication, saying “”I think it is fair to say that we would have liked to have seen it before it was published,” [Paul Keim, chairman of the National Science Advisory Board for Biosecurity], and the “…altered bird flu virus could mutate in dangerous ways if unleashed in nature”.

I am more worried, to be perfectly honest, over the dangerous ways the the wild type virus could mutate IN nature, given that mutants can be selected so apparently easily!

A Short History of the Discovery of Viruses – Part 2

7 February, 2012

The following text has now appeared in modified form in an ebook, for sale for US$4.99 on the iBooks Store

The Ultracentrifuge, Eggs and Flu

The ultracentrifuge

A technical development that was to greatly advance the study of viruses was begun in 1923, but only reached fruition by the 1930s: this was the ultracentrifuge, invented and developed first by Theodor (“The”) Svedberg in Sweden as a purely analytical tool, and later by JW Beams and EG Pickels in the USA as an analytical and preparative tool.  The ultracentrifuge revolutionised first, the physical analysis of proteins in solution, and second, the purification of proteins, viruses and cell components, by allowing centrifugation at speeds high enough to allow pelleting of subcellular fractions.

Analytical centrifugation and calculation of molecular weights of particles gave some of the first firm evidence that certain proteins, and virus particles, were large, regular objects.  Indeed, it came to be taken as a given that one of the fundamental properties of a virus particle was its sedimentation coefficient, measured in svedbergs (a unit of 10-13 seconds, shown as S20,W).  This is also how ribosomes of pro- and eukaryotes came to be named: these are known as 70S (prokaryote) and 80S ribosomes, respectively, based on their different sedimentation rates.

The Official Discovery of Influenza Virus

In 1931, Robert Shope in the USA managed to recreate swine influenza by intranasal administration of filtered secretions from infected pigs.  Moreover, he showed that the classic severe disease required co-inoculation with a bacterium – Haemophilus influenza suis – originally thought to be the only agent.  He also pointed out the similarities between the swine disease and the Spanish Flu, where most patients died of secondary infections.  However, he also suggested that the virus survived seasonally in a cycle involving the pig, lungworms, and the earthworm, which is now known to be completely wrong.

This notwithstanding, he found that people who had survived infection during the 1918 pandemic had antibodies protecting them against the swine flu virus, while people born after 1920 did not, which showed that the 1918 human and swine flu viruses were very similar if not identical. This was a very relevant discovery for what happened much later, in the 2009 influenza pandemic, when the same virus apparently came back into the human population from pigs after circulating in them continuously since 1918.

Shope went on in 1932 to discover, with Peyton Rous, what was first called the Shope papillomavirus and later Cottontail rabbit papillomavirus: this causes benign cancers in the form of long hornlike growths on the head and face of the animal. This may explain the sightings in the US Southwest of the near-mythical “jackalope”.

Influenza viruses in pigs

Influenza viruses in pigs

Patrick Laidlaw and William Dunkin, working in the UK at the National Institute for Medical Research (NIMR), had by 1929 successfully characterised the agent of canine distemper – a relative of measles, mumps and distemper morbilliviruses – as a virus, proved it infected dogs and ferrets, and in 1931 got a vaccine into production that protected dogs.  This was made from chemically inactivated filtered tissue extract from infected animals.  Their work built on and completely eclipsed earlier findings, such as those of Henri Carré in France in 1905, who first claimed to have shown it was a filterable agent, and Vittorio Puntoni, who first made a vaccine in Italy from virus-infected brain tissue inactivated with formalin in 1923.

Influenza and Ferrets: the Early Days

Continuing from Laidlaw and Dunkin’s work in the same institute, Christopher Andrewes, Laidlaw and W Smith reported in 1933 that they had isolated a virus from humans infected with influenza from an epidemic then raging.  They had done this by infecting ferrets with filtered extracts from infected humans – after the fortuitous observation that ferrets could apparently catch influenza from infected investigators!  The “ferret model” was very valuable – see here for modern use of ferrets – as strains of influenza virus could be clinically distinguished from one another.

Eggs and Flu and Yellow Fever

Influenza virus and eggs: large-scale culture

Frank Macfarlane Burnet from Australia visited the NIMR in the early 1930s, and learned a number of techniques he used to great effect later on.  Principal among these was the technique of embryonated egg culture of viruses – which he took back to Melbourne, and applied to the infectious laryngotracheitis virus of chickens in 1936.  This is a herpesvirus, first cultivated by JR Beach in the USA in 1932: Burnet used it to demonstrate that it was possible to do “pock assays” on chorioallantoic membranes that were very similar to the plaque assays done for bacteriophages, with which he was also very familiar.  Also in 1936, Burnet started a series of experiments on culturing human influenza virus in eggs: he quickly showed that it was possible to do pock assays for influenza virus, and that

“It can probably be claimed that, excluding the bacteriophages, egg passage influenza virus can be titrated with greater accuracy than any other virus.”

Max Theiler and colleagues in the USA took advantage of the new method of egg culture to adapt the French strain of yellow fever virus (YFV) he had grown in mouse brains to being grown in chick embryos, and showed that he could attenuate the already weakened strain even further – but it remained “neurovirulent”, as it caused encephalitis or brain inflammation in monkeys.  He then adapted the first YFV characterised – the Asibi strain, from Ghana in 1927 – to being grown in minced chicken embryos lacking a spinal cord and brain, and showed in 1937 that after more than 89 passages, the virus was no longer “neurotrophic”, and did not cause encephalitis.   The new 17D strain of YFV was successfully tested in clinical trials in Brazil in 1938 under the auspices of the Rockefeller Foundation, which has supported YFV work since the 1920s.  The strain remains in use today, and is still made in eggs.

Virus purification and the physicochemical era

Given that the nature of viruses had prompted people to think of them as “chemical matter”, researchers had attempted from early days to isolate, purify and characterise the infectious agents.  An early achievement was the purification of a poxvirus in 1922 by FO MacCallum and EH Oppenheimer. 

Much early work was done with bacteriophages and plant viruses, as these were far easier to purify or extract at the concentrations required for analysis, than animal or especially human viruses. 

CG Vinson and AM Petre, working with the infectious agent causing mosaic disease in tobacco – tobacco mosaic virus, or TMV – showed in 1931 that they could precipitate the virus from suspension as if it were an enzyme, and that infectivity of the precipitated preparation was preserved.  Indeed, in their words:

“…it is probable that the virus which we have investigated reacted as a chemical substance”.

Viruses in Crystal

An important set of discoveries started in 1935, when Wendell Stanley in the USA published the first proof that TMV could be crystallised, at the time the most stringent way of purifying molecules.  He also reported that the “protein crystals” were contaminated with small amounts of phosphorus.  An important finding too, using physical techniques including ultracentrifugation and later, electron microscopy, was that the TMV “protein” had a very high molecular weight, and was in fact composed of large, regular particles.  This was a very significant discovery, as it indicated that some viruses at least really were very simple infectious agents indeed.

TMV particle: 95% protein, 5% RNA

However, his conclusion that TMV was composed only of protein was soon challenged, when Norman Pirie and Frederick Bawden working in the UK showed in 1937 that ribonucleic acid (RNA) – which consists of ribose sugar molecules linked by phosphate groups – could be isolated consistently from crystallised TMV as well as from a number of other plant viruses, which accounted for the phosphorus “contamination”.  This resulted in the realisation that TMV and other plant virus particles – now known to be virions – were in fact nucleoproteins, or protein associated with nucleic acid.

Stanley received a share of the Nobel Prize in Chemistry in 1946 for his work on TMV: it is instructive to read his acceptance speech from the time to realise what the state of the science that was becoming virology was at the time.  He wrote:

“Since the original discovery of this infectious, disease-producing agent, known as tobacco mosaic virus, well over three hundred different viruses capable of causing disease in man, animals and plants have been discovered. Among the virus-induced diseases of man are smallpox, yellow fever, dengue fever, poliomyelitis, certain types of encephalitis, measles, mumps, influenza, virus pneumonia and the common cold. Virus diseases of animals include hog cholera, cattle plague, foot-and-mouth disease of cattle, swamp fever of horses, equine encephalitis, rabies, fowl pox, Newcastle disease of chickens, fowl paralysis, and certain benign as well as malignant tumors of rabbits and mice. Plant virus diseases include tobacco mosaic, peach yellows, aster yellows, potato yellow dwarf, alfalfa mosaic, curly top of sugar beets, tomato spotted wilt, tomato bushy stunt, corn mosaic, cucumber mosaic, and sugar cane yellow stripe. Bacteriophages, which are agents capable of causing the lysis of bacteria, are now regarded as viruses”.

Two of the most interesting things about the article, however, are the electron micrographs of virus particles – Stanley had one of the first electron micrsoscopes available at the time –  and the table of sizes of viruses, proteins and cells that had been determined by then by techniques such as ultracentrifugation and filtration: TMV was known to be rodlike, 15 x 280 nm; vaccinia was 210 x 260 nm; poliomyelitis was 25 nm; phages like T2 were known to have a head-and-tail structure.

Seeing is Believing: the Electron Microscope

First Electron Microscope with Resolving Power Higher than that of a Light Microscope. Ernst Ruska, Berlin 1933 Wikipedia CC BY-SA 3.0,

First Electron Microscope with Resolving Power Higher than that of a Light Microscope. Ernst Ruska, Berlin 1933
Wikipedia CC BY-SA 3.0,

The development of the electron microscope, in Germany in the 1930s, represented a revolution in the investigation of virus structures: while virions of viruses like variola and vaccinia could just about be seen by light microscopy – and had been, as early as 1887 by John Buist and others – most viruses were far too small to be visualised in this way. 

While Ernst Ruska received a Nobel Prize in 1986 for developing the electron microscope, it was his brother Helmut who first imaged virus particles – using beams of electrons deflected off virus particles coated in heavy metal atoms.  From 1938 through the early 1940s, using his “supermicroscope”, he imaged virions of poxviruses, TMV, varicella-zoster herpesvirus, and bacteriophages, and showed that they were all particulate – that is, they consisted of regular and sometimes complex particles, and were often very different from one another.  He even proposed in 1943 a system of viral classification on the basis of their perceived structure.

While electron microscopy was also used medically to some extent thereafter – for example, in differentiating smallpox from chickenpox by imaging particles of variola virus and varicella-zoster virus, respectively, derived from patients’ vesicles – its use was limited by the expense and cumbersome nature of sample preparation. For example, the micrographs in Stanley’s 1946 paper were all done with samples “…prepared with gold by the shadow-casting technique”.

The use of the cumbersome technique of metal shadow-casting, and the highly inconvenient nature of electron microscopy as a routine tool all changed from 1959 onwards, when Sydney Brenner and Robert Horne published “A negative staining method for high resolution electron microscopy of viruses”.  This method involves the use of viruses in liquid samples deposited on carbon-coated metal grids, and then stained with heavy-metal salts such as phosphotungstic acid (PTA) or uranyl acetate.

This simple technique revolutionised the field of electron microscopy, and within just a few years much information was acquired about the architecture of virus particles. Not only were the overall shapes of particles revealed, but also the details of the symmetrical arrangement of their components. Some beautiful examples can be seen here, at the Cold Spring Harbor site.

Depiction of the effects of using a heavy metal salt solution to negatively stain particles on a carbon film. The stain (dark) pools around the particles (light).  Human rotavirus particles, stained from below (left) and by immersion (right).
Images copyright LM Stannard

Depiction of the effects of using a heavy metal salt solution to negatively stain particles on a carbon film. The stain (dark) pools around the particles (light). Human rotavirus particles, stained from below (left) and by immersion (right).
Images copyright LM Stannard

Click here for Part 1: Filters and Discovery

here for Part 3: Phages, Cell Culture and Polio

and here for Part 4: RNA Genomes and Modern Virology

Copyright Edward P Rybicki and Russell Kightley, February 2015, except where otherwise noted.

Protection against Killer Flu! No, not H5N1…

17 January, 2012

Depiction of virus mixing in a pig

In an issue of Virus Research devoted to commemorating the career of Brian Mahy, who retired recently from the CDC and now as Editor-in-Chief of Virus Research, there is a paper by Taubenberger and Kash on the 1918 H1N1 flu – wherein they say the following:

“In a recent set of experiments, it was shown that mice vaccinated with the monovalent 2009 pandemic H1N1 vaccine were completely protected in a lethal challenge model with the 1918 influenza virus…”

Because the modern pandemic “swine flu” H1N1 HA protein descends directly from the 1918 virus, but in pigs rather than in humans. Remember all the hype around THAT work – resurrecting the legendary Spanish Flu, and how it would kill us all? And here we already have a vaccine, that will completely protect us.

We have vaccine candidates against H5 as well. Time for a universal flu vaccination campaign and pre-emptive strike, people!

Killer Flu hype grinds on

16 January, 2012

The Independent today has a story entitled”Killer flu doctors: US censorship is a danger to science” – thanks, AJ Cann! – which details how the folk in the Netherlands who did the work do not think the USA should not be “…be allowed to dominate the debate over who controls sensitive scientific information that could be misused in biowarfare terrorism”.

Influenza A viruses mixing in susceptible hosts


Well, yes, join the club, guys!  The article is quite reasonable – apart from a couple of points, noted below – but it ends on a suitably alarmist note “…the chances of a laboratory strain of H5N1 escaping into the wild remain high if it is stored in conventional flu-virus labs”, and “Regulators should not be sitting idly by, while the threat of a man-made pandemic looms”.  Really?  The undoubtedly very small amount of mutated flu that exists, relative to any engineered bioweapon in US or Russian labs, represents a clear and present threat to world health?

What dismayed me most, however, was how horrifyingly uninformed most of the commenters are – about H5N1 in particular, and science and science funding in general….!  As I could not comment there – Disqus broke, apparently – I will do so here.

As for labelling the article “Killer Flu Doctors” – really!  A little sensationalism, anyone??  Concerning the comment “…the details could be misused by rogue states or by biowarfare terrorists with access to rudimentary scientific knowledge and fairly standard laboratory equipment”: as a practicing molecular virologist, I can tell you that you would need a lot more than “rudimentary scientific knowledge” – you’d need skill in molecular biology, and especially in reverse genetics of (-)strand RNA viruses, as well as more than “fairly standard equipment” to even BEGIN to hope to make anything like a “killer” H5N1 from published details.

Additionally, a H5 N1 flu virus that is  aerosol transmitted in ferrets – and how efficient was that, I ask? – may NOT be similarly transmissible or as easily (if it was easy) between humans.  I will point out that people thought the SARS CoV outbreak was the “Big One” flu pandemic – but although it was aerosol transmissible, it wasn’t nearly as efficiently transmitted as the common flu, so did not spread as fast.

Thus, most of what the doomsayers are predicting could be simply hype – meanwhile, in countries far away from the US which seeks to regulate such work, the virus is already endemic, and mutating freely – and it would be VERY useful indeed to know what to look for!

Influenza virus migrations – a lesson from 1961

13 January, 2012

Influenza A viruses carried by birds

I have been doing quite a lot of digging into virus history recently, and it was interesting to pick up – while checking on who had published what from our University on viruses – a paper from 1966 describing “The isolation and classification of Tern virus: Influenza Virus A/Tern/South Africa/1961″ by WB Becker of the Virus Research Unit here at UCT.  It is interesting because it was isolated from sick migratory Common Terns along the south coast of South Africa, which were infected as part of an “explosive epizootic” which resulted in many deaths.  It became more interesting when it was shown in 1967 to cause few or no symptoms in Swift Terns but was shed in large amounts, to be highly pathogenic in chickens, and was subsequently typed as H5N3.

The discussion of the original paper was not only highly prescient, but may be completely valid today: a significant quote follows.

The isolation of Tern virus raises interesting epidemiological possibilities. The outbreak in chickens in Scotland caused by Chicken/Scot. virus preceded the Tern epizootic by about 17 months and occurred during stormy weather which drove sea-birds a little inland to take shelter. Large numbers ofHerring Gulls (Larus argentatus) were at that time working thef arm at which the out break in chickens occurred in November 1959 (J. E. Wilson, personal communication). The chickens might have contracted the infection from sea-birds, a viewpoint possibly supported by the preceding mass mortality in Kittiwakes (Rissa tridactyla) and Fulmars (Fulmaris glacialis) from February to August 1959 (Joensen, 1959) off the coast of Britain and Scandinavia. Unfortunately the aetiology of the last-mentioned outbreak was not investigated, but it is tempting to think it was caused by the Tern virus which was isolated at Cape Town some 18 months later in 1961, from migrant European Common Terns.

One might postulate: that certain sea-birds suffer latent or sporadic infection with avian influenza; that epizootics may be precipitated in them by conditions of stress, e.g. poor feeding under unfavourable weather conditions such as pre- ceded the Tern epizootic; and that spread to other sea-birds or domestic poultry may occur. [my emphases – Ed]

The 1967 tern infection paper continues this theme:

The outbreak in chickens in Scotland in 1959 (Dr J. E. Wilson, personal communication) and the Tern epizootic in 1961 were caused by influenza A viruses with closely related strain specific antigens which were unrelated to those of any previously known influenza A viruses. Recently strains of influenza A related to the Tern and Scottish viruses were isolated from turkeys in Canada (Dr G.Lang, personal communication). This lends further support to the hypothesis that migrating sea-birds such as the Common Tern may transmit avian influenza A viruses to domestic poultry.

This was followed up more recently (2002) by a paper describing transmission of the tern virus to laughing gulls:

This investigation detailed the clinical disease, gross and histologic lesions, and distribution of viral antigen in juvenile laughing gulls (Larus atricilla) intranasally inoculated with either the A/tern/South Africa/61 (H5N3) (tern/SA) influenza virus or the A/chicken/Hong Kong/220/97 (H5N1) (chicken/HK) influenza virus, which are both highly pathogenic for chickens. Neither morbidity nor mortality was observed in gulls inoculated with either virus within the 14-day investigative period. Gross lesions resultant from infection with either virus were only mild…. Antibodies to influenza viruses …at 14 DPI were detected only in the two tern/SA-inoculated gulls and not in the two chicken/HK-inoculated gulls.

Their conclusions, too, were rather disturbing:

The positive isolation of the tern/SA and chicken/HK viruses from the OP and cloacal swabs suggests that, with adequate exposure, gulls could serve as hosts for these and possibly other HPAI viruses. Isolation of the A/gull/Germany/79 (H7N7) virus during a HPAI outbreak in Eastern Europe provides further evidence to support the potential for pelagic birds to serve as biological vectors for (HP)AI viruses (D. J. Alexander, pers. comm., originally referenced in 29). This is a significant finding in terms of the epidemiology of AI viruses, especially considering the fact that the chicken/HK virus was a zoonosis (26,27). Moreover, pelagic birds have been implicated as the source for other AI viruses that transmitted to and may have caused disease in mammals (8,13).

Everybody is obsessed with H5N1: maybe we should be a little more concerned with what may be raining down from above, as seabirds carry recombinant / reassortant viruses from areas of high H5N1 endemicity around the world.