jeudi 30 juin 2011
Ci dessous le discours du Prix Nobel de Medecine 1996 Peter Doherty, lors de la 37e réunion de la FAO.
A great achievement and the road ahead
Your Excellencies, friends and colleagues,
My role in this assembly is, I believe, to speak as a scientist and to convey the congratulations of the broader scientific
community.Congratulations to the key policy makers and facilitators of the FAO and the OIE, congratulations to the political leaders and administrators
in the various Nation States and, above
all, congratulations to the people on the ground, the
veterinary scientists, the laboratory workers, the field officers, the communicators, the farmers and
the cattle herders who brought the
scourge of rinderpest to an end.
Then, as a research scientist who has spent a long career working on animal virus infections and immunity,
it may be appropriate for me to say a little about the issues that
remain as we seek to deal with other problematic virus diseases. Modern molecular
science is immensely powerful though, to tell the truth, it played little part in the eradication
Nowhere is the "one world" concept of veterinary and human medicine more relevant than in the area of microbial disease. That’s true of the zoonoses like, for example, ebola, rabies, SARS and Nipah virus, all bat-borne infections that transmit to us, often via a domestic animal
"amplifier." Then, there’s the issue of nutritional deficit in a world that FAO estimates
has in excess of a billion people in hunger. When it comes to countering inadequate micronutrient, calorie and high value protein intake, alleviating the toll of infectious disease in both animals and people has to be a major priority.
Though not a zoonosis in the conventional sense, contemporary molecular genetic approaches suggest that rinderpest
virus and human measles virus evolved from a common ancestor some 10 to 12 centuries back. Now, as we celebrate the eradication of rinderpest its sibling, measles, is still with
us. As a one-host pathogen of humans, it should also be possible to eliminate measles from the planet. The problem is the anti-vaccination movements in the advanced
countries. Many young parents in Europe, the USA and so forth have never seen the common diseases of childhood and, though they may be
well educated in the liberal arts sense, know little of pathology and do not accept that vaccination is a collective responsibility.
We should also say a little of the scientific background to the eradication of rinderpest. The vaccine used was developed decades back by World Food Prize Laureate, the late Walter Plowright, who built on earlier
experiments by scientists like JT Edwards at what is now the Indian Veterinary Research Institute. In fact, the history of trying to deal with rinderpest by some form of controlled
infection goes back to times before Louis Pasteur and Robert Koch established the germ theory of infectious disease in the mid to late 19th century.
The same is true for smallpox, the only other virus that has ever been eliminated. Way back in 1796, Edward Jenner took his
original vaccinia virus from
the teat of an infected cow. Meeting in Rome we
"Vacca" is the Latin word for cow, so vaccination itself has a bovine origin. By the 1920’s, following the broad
principle of attenuation discovered for fowl cholera (the 2nd ever vaccine) by Louis Pasteur, Edwards used 600 serial transfers through goats to establish a less virulent strain of rinderpest virus. Then the saferand cheaper Plowright vaccine was developed much
later by passage through tissue culture.
Scientifically at least, the eradication of rinderpest
reflects approaches based in long-established quarantine and test and slaughter policies, and what might be described
as ’steam" virology. Given the resources and the political will, it is
clearly feasible to think in terms of controlling some other major infections of domestic
animals in this way. Obvious candidates are the rinderpest-like PPR and, perhaps, Newcastle disease and foot and mouth
Other infections, like African swine fever
look almost as difficult as human HIV/AIDS. Despite spending hundreds of millions of dollars and applying every
relevant advance in molecular technology, AIDS remains refractory when it comes to vaccine development. Though the chemists and pharmacologist have done well, drug therapy
has little relevance to infections of domestic animals. We can’t give up on AIDS vaccines, but it is
important to ask the question whether vaccination is the way to go when it comes to all veterinary infectious diseases.
Some infections, like avian influenza, will always be with
us. A broad spectrum of influenza A viruses is maintained in nature by a diversity of wild water fowl. There is thus no obvious
way that these viruses could ever be eliminated from the planet. Vaccination has only been partially
effective in controlling the continuing, high-path H5N1 epidemic, which has, to date, led to the loss of some 500 million to a billion
domestic chickens. That represents an enormous loss, both of high value protein and in economic
What may well be feasible with a rapidly reproducing species like the domestic chicken is to use contemporary molecular science to
establish genetically-modified birds that resist infection with all influenza A viruses. Apart from the benefits to producers and consumers, removing the mutant virus incubators
that large chicken houses represent should also serve to minimize the emergence of novel pandemic viruses that infect humans and/or other domestic animal species. Early experiments look encouraging, but a major issue here
is the acceptability of such GM birds for human consumption.
Science continues to offer extraordinary possibilities for the control of animal disease. There is no lack of talent in the veterinary research community, which functions as part of the
"one world" of modern molecular technology and medicine. What is essential is to maintain the necessary funding and, when innovative solutions are reached, to ensure that novel strategies
for disease control are socially acceptable. Clearly, we need continued leadership and co-ordination from the FAO and the OIE, working in concert with
other International Agencies and the various Nation States. Sustaining animal agriculture and strong veterinary services must continue to be a major, global priority as we seek to feed all the human family.
Peter C Doherty DVSc FRS
Nobel Laureate for Medicine