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| 2005 CSIRO Report |
#13,610
Between a steadily rising global population, increasingly erratic climatic conditions, and the constant threat of epizootic and other agricultural diseases, there are genuine concerns on how we feed an increasingly hungry planet going forward.
The FAO's report The State of Food Security and Nutrition in the World 2017 shows a sharp rise in food insecurity around the world since 2014 (see chart below), and warns: AFTER A PROLONGED DECLINE, WORLD HUNGER APPEARS TO BE ON THE RISE AGAIN.
Avian influenza has long been known to circulate in wild aquatic birds of the orders Anseriformes (ducks, geese, and swans, etc.) and Charadriiformes (shorebirds, gulls, and auks, etc.) - and importantly - these species can often carry these viruses will little or no ill effect.
Less well adapted to the viruses, and therefore far more susceptible to illness, are the Galliformes; an order of heavy-bodied ground-feeding birds that includes turkey, chicken, quail and pheasant.
Commercially raised gallinaceous birds are easily infected by both low and high path viruses, and can rapidly succumb to HPAI infection.Over the past several decades we've seen massive losses in the poultry sector due to an array of (mostly) H5 and H7 HPAI viruses, causing not only severe economic losses, but also increases in food insecurity around the world (see Iran: Bird Flu, Food Insecurity & Civil Unrest).
For the past 20 years, serious consideration has been given to developing - either through selective breeding or genetic modification - a flu resistant chicken, in the hopes that it would reduce not only the risk to the poultry sector, but might also diminish the chances of seeing an avian flu pandemic.
Six years ago, in CSIRO: The Quest For Flu Resistant Poultry, we looked at the progress made in this endeavor by Australia's national science agency CSIRO (Commonwealth Scientific and Industrial Research Organisation).
One of those projects involved CSIRO research scientist, Dr Tim Doran, who was using a technique called gene silencing to “switch off” genes that make chickens susceptible to HPAI H5 viruses (see Silencing the bird flu gene: scientists prep live hen trials).Dr. Doren is back today, along with other researchers from Australia and the Netherlands, with a review of the options for creating flu resistant poultry, the progress to date, and the challenges that still lie ahead in the following review article from the journal Viruses.
I've only included a couple of small excerpts, so you'll want to follow the link to read it in its entirety. When you return, I'll have a postscript.
Review
Received: 27 September 2018 / Accepted: 12 October 2018 / Published: 15 October 2018
Abstract:
Influenza A virus (IAV) represents an ongoing threat to human and animal health worldwide. The generation of IAV-resistant chickens through genetic modification and/or selective breeding may help prevent viral spread. The feasibility of creating genetically modified birds has already been demonstrated with the insertion of transgenes that target IAV into the genomes of chickens. This approach has been met with some success in minimising the spread of IAV but has limitations in terms of its ability to prevent the emergence of disease.
An alternate approach is the use of genetic engineering to improve host resistance by targeting the antiviral immune responses of poultry to IAV. Harnessing such resistance mechanisms in a “genetic restoration” approach may hold the greatest promise yet for generating disease resistant chickens. Continuing to identify genes associated with natural resistance in poultry provides the opportunity to identify new targets for genetic modification and/or selective breeding.
However, as with any new technology, economic, societal, and legislative barriers will need to be overcome before we are likely to see commercialisation of genetically modified birds.
(SNIP)
8. Conclusions
The recent outbreaks of H5Nx viruses across the world highlight the continual threat that avian influenza viruses pose to both poultry and human health. Rapid advances in genomics and gene editing suggest that disease resistant, genetically modified chickens could represent a viable solution to the problem of avian influenza.
However, whilst the creation of influenza resistant chickens is technically possible, there still remain many barriers in place blocking their commercial implementation. These include issues such as consumer concerns and a detailed assessment of their commercial and environmental viability.
It is possible some of these issues can be circumvented and/or mitigated with alternative approaches such as selective breeding and/or genetic restoration. However, regardless of the methodology used, novel approaches to address the issue of avian influenza must remain a global health priority.
Over the years we've looked at the relative susceptibility of different bird species to Highly Pathogenic Avian Influenza, including.
Vet. Micro.: Experimental Infection Of Mandarin Ducks & Pigeons With HPAI H5N8
Avian Path: Susceptibility of Wild Passerine Birds To HPAI H5N1
Emerg. Microbes & Infections: Wild Ducks Shed (2014-15) HPAI H5N8 Asymptomatically
DEFRA: Assessing The Risk Of Pigeon Racing In Spreading Avian Influenza
As a general rule, waterfowl are the most resistant to infection and/or illness - poultry are the most susceptible - and passerine species (perching birds) fall somewhere in between.
However, when the H5N8 virus sparked Europe's largest epizootic over the winter of 2016/17, it exhibited a number of genetic and behavioral changes following a reassortment that took place sometime in the spring of 2016 (see EID Journal: Reassorted HPAI H5N8 Clade 2.3.4.4. - Germany 2016).
Among the changes, this reinvented HPAI H5 virus displayed rapid geographic spread (including to Africa & the Middle East), increased virulence and mortality in wild birds (including waterfowl), and a greatly expanded avian host range.Finding ways to make farm animals more disease resistant - particularly without feeding them a constant diet of antibiotics and antivirals - is an incredibly important goal, and worthy of pursuit.
But flu viruses have continually demonstrated an ability to evolve, adapt, and overcome when confronted by barriers like vaccines and antivirals. And recently, we can add HPAI H5's recent persistence and increased pathogenicity in waterfowl.Assuming the substantial challenges of creating a `flu-resistant' chicken can be met - either through genetic modification or selective breeding - and that it is broadly accepted by both the public and the poultry industry, the obvious concern will be just how permanent of a solution this actually turns out to be.
And that is something I don't expect we can really know until we try.
