CRX08: The devil you try to know

Last year, Professor Anne Kelso took over as director of the World Health Organisation (WHO) Collaborating Centre for Reference and Research in Influenza in Melbourne. Moving from Queensland early in 2007 to take up the new role in Melbourne was a return to old stamping ground for Kelso. She not only did her doctoral studies at the University of Melbourne under the supervision of Sir Gustav Nossal, but also spent 10 years cementing her international reputation and research career in immunology at the Walter and Eliza Hall Institute.

So, after 12 years in the subtropics at the Queensland Institute of Medical Research and as director of the CRC for Vaccine Technology in Brisbane, the call of the plane trees and the chance to be part of a global health effort was too much.

In a plenary session on challenges in large-scale clinical research at the Clinical Research Excellence (CRX08) conference in Brisbane in August, Kelso will discuss the part her centre plays in the on-going global battle against influenza, both the seasonal bouts and the potential pandemic influenza that is likely to arise from avian flu.

The Commonwealth-funded collaborating centre in Melbourne is part of a global public health network for influenza surveillance, originally established by the WHO in 1947 to study the origins of epidemic and pandemic influenza strains, and to generate new virus strains for vaccine production. This network now comprises four WHO Collaborating Centres (Melbourne, London, Atlanta and Tokyo), and 112 national influenza centres in 80 countries around the world. Australia has three of these, in Sydney, Melbourne and Perth. According to Kelso, it is probably the most extensive and advanced network known for monitoring a single pathogen.

The Australian flu centre employs around 14 people, all of whom work in some aspect of influenza surveillance, research or training. It was set up originally in 1992 by the Commonwealth Serum Laboratories (CSL), and in 2006 its management was handed over to Melbourne Health, and specifically to the Victorian Infectious Diseases Reference Laboratory (VIDRL) division.

Already part of VIDRL operationally, the Influenza Centre will physically move to renovated facilities there in the near future, including new PC2 and PC3 laboratories, as well as specialised rooms for isolating human influenza viruses destined for human vaccines.

---PB--- Know thine enemy

The four WHO Collaborating Centres act as global collection points for influenza virus samples sent from the national laboratories and other diagnostic laboratory or medical facilities in the region. The viruses collected undergo detailed antigenic and genetic characterisation to monitor changes in influenza virus around the world over time. Most of this work involves the seasonal viruses and basically, WHO is watching out for two things - how the virus population as a whole is changing globally from season to season, and anything unusual that needs more thorough analysis.

To measure the seasonal changes in influenza virus, or antigenic drift, samples are compared to a panel of reference strains. Antisera against these reference strains are raised in ferrets, which are the best-established animal model of influenza infection in humans, and then used to test collected samples.

"Antisera are also raised against anything new and interesting as a future reference strain, or more importantly, as a future vaccine strain," Kelso says. "What we really want to know is how far the virus has drifted in antigenicity and genetic profile from what we saw in previous northern and southern hemisphere seasons."

Of course, only a small proportion of the influenza virus out there is being monitored by the WHO efforts. Most people who contract the flu do not seek medical care, and of those that do, only a few are officially reported with appropriate samples sent to the WHO labs. However, according to Kelso, Australia has good systems set up for monitoring influenza-like illness, through hospitals and some GP surveillance networks.

Additionally, the detection of flu is notifiable in all states in Australia except South Australia. In 2007, the Collaborating Centre received about 2600 samples for analysis. These samples came mostly from within Australia, but many samples and virus isolates also arrived from other countries in the region including New Zealand, Malaysia, The Philippines and Macau.

Members of the four WHO Collaborating Centres then meet in Geneva twice a year to review all the data collected over the previous six months and issue a public statement about the latest antigenic trends in influenza virus wear for the following winter. This information is used to recommend virus strains for inclusion in the next seasonal vaccines for the northern and southern hemispheres, respectively.

What follows is then an intensive period of work for all concerned to culture suitable virus by its antigenic properties to include in the vaccin, and then grow enough up in eggs for the relevant companies to produce vaccine and release it into the market. "Even though it is many months between our meeting and the release of the vaccine, it is a very tight timeline that the companies face," she says.

The two A-type viruses circulating in humans at the moment, H1N1 and H3N2, both originated as pandemics and their history is quite interesting. "H1N1 is the progeny of the virus that caused the 1918 influenza pandemic virus, which after the pandemic became established in humans, circulated until the 1930s, and then disappeared," Kelso says.

"It re-emerged in Russia in 1977 and has been circulating in humans ever since. So, it has now drifted a long way from the original pandemic form. It is also only the A viruses that give rise to pandemics from time to time. The B-type viruses are not as variable and are human strains originally." ---PB--- Avoid the chook shed

In terms of where the next influenza pandemic might come from, the bird flu strain H5N1 continues to be a big concern, according to Kelso. "It has spread so far and there have been many human cases. It continues to infect poultry flocks and has spread throughout many wild bird populations around the world, across Asia through into the Middle East and Europe and into Africa. We are very fortunate that it has not yet spread into populations in the Americas, North or South, or into Australasia."

Although migratory birds contribute to the virus spread, the poultry trade is seen as the biggest threat - live birds and uncooked meat being transported around the world. It is impossible to predict, however, whether H5N1 is more likely than another influenza virus to mutate and give rise to a pandemic, and the WHO is closely monitoring several other avian viruses.

This is where the work of the influenza surveillance network becomes so vital. "Certainly, any human infections that turn out to be not caused by a standard seasonal human influenza virus require particular attention," Kelso says.

The issue of transmission from birds to human and potential transmission between humans is scientifically challenging and the subject of intensive research in the area. One possibility for an influenza virus striking the right variation for human-to-human spread is by co-infection of a human cell by a human virus and an avian virus like H5N1, Kelso explains.

The influenza virus has a segmented RNA genome in eight strands, and thus can undergo re-assortment. Potentially, then, if two viruses were present at the same time in the same cell, a new virus might be created with RNA material from both parent strains.

"In that scenario, you could get a human virus in which only the haemagglutinin molecule has changed. So, it would be easily transmissible between humans, but we would have no immunity against it."

This scenario was proven in principle by a group in Atlanta, who used reverse genetics to create a viable, hybrid virus by mixing the genomes of H5N1 and various human viruses. Kelso reassuringly highlights that multiple changes must have to happen because, if only one or two mutations had to happen, it probably would have by now.

---PB--- Applied science

Australia and many other countries have very advanced plans to prepare for and combat pandemic influenza, wherever and whenever it appears. In addition to her role as centre director, Kelso also sits on some of the committees involved in formulating and updating the national pandemic plans, including the National Influenza Pandemic Action Committee. And the inside word is that Australia is well placed globally in its preparedness planning.

So much so that a third edition of the Australian Health Management Plan for Pandemic Influenza (AHMPPI) is due out any day now. Each version updates the previous one based on new global information and thinking of what needs to be done.

Having now been in this new position of centre director for well over a year, Kelso can finally lift her head long enough to reflect on the latest challenge in her impressive career path. "It is a completely different field of activity from what I was doing before as a biomedical researcher (for over 20 years) and then as head of a CRC. This is now really in the public health arena."

The fact that the work is still firmly based in laboratory science, but part of a global public health activity, was a major attraction for Kelso in making the shift back to Melbourne. "Influenza is an important disease, potentially extremely important. I am enjoying being part of the global surveillance of this virus - it feels worthwhile."

Kelso is still keeping a foot in the research world with an honorary position in the Department of Microbiology at the University of Melbourne. "I go to lab meetings there and still participate in grant application processes, although now of course for influenza research. We are particularly interested in how basic understanding of the immune response to influenza can be used to inform the development of better vaccines - not just seasonal flu but also for pandemic virus."

To the obvious question, Kelso replies that when the pandemic hits, she will probably not have the option of staying at home, although recommends that those that can should. "Our centre will definitely have a big role to play, in analysing the virus, monitoring antiviral drug resistance, potentially monitoring immunity to the virus - so I think my main concern will be to make sure that work happens."