Avian flu vaccine on the brinkJanuary 10th, 2011 in Medicine & Health / Medical research
Pox virus infecting avian cells - image captured using confocal microscopy in the Central Laser Facility. Credit: STFC and
Avian flu vaccine on the brinkJanuary 10th, 2011 in Medicine & Health / Medical research
Pox virus infecting avian cells - image captured using confocal microscopy in the Central Laser Facility. Credit: STFC and Oxford Brookes University
A collaboration between BBSRC and STFC-funded scientists has been using a new form of low energy microscopy to observe how poxviruses interact with components inside live cells. Genetically modified fowlpox viruses have been used extensively in Mexico and southeast Asia to vaccinate chickens against bird flu and the scientists hope that the technique will help them develop more effective vaccines that reduce the chances of healthy birds acting as a reservoir for influenza virus. The research was published in the December 2010 edition of the Journal of Virology.
Dr. Ananya Jeshtadi, from Dr. Mike Skinner's group at Imperial College London, carried out the study as part of the BBSRC Combating Avian Influenza initiative, which aims to increase understanding of how avian influenza interacts with its animal hosts in order to control its spread more effectively.
Dr. Skinner said: "The current generation of fowlpox-based vaccines are really good at stopping chickens from getting ill when they come into contact with flu but they don't always stop the birds from getting infected. Because of this, around a quarter of vaccinated birds still act as carriers of the disease and pass it on to others. Our hope is that we can engineer a new vaccine that makes this much less likely."
Since being introduced in Mexico in the mid 1990s, fowlpox-based vaccines have become an important weapon in the fight against avian influenza (more than 2 billion doses have been used) and are currently being used as part of a massive campaign to protect some 5 billion poultry in China. The so-called'recombinant vaccine' is based on a fowl pox virus that has been modified to display an influenza protein on the surface of the infected cell. The immune system of a vaccinated chicken is primed to respond to the influenza protein, meaning that the bird can successfully combat flu when subsequently exposed to it. With recombinant vaccines, farmers can also test whether chickens have been given the vaccine or have been exposed to the influenza virus, which is less easy with flu-based vaccines.
Dr. Skinner continued: "The problem with current influenza vaccines is that they don't stimulate the part of the immune system that would normally clear out any infected cells when the chickens are exposed to flu. What we hope is that this work will enable us to identify factors in the fowlpox-based vaccines that prevent chickens from mounting responses to eliminate infected cells. Once we know what these are, we may be able to develop an improved vaccine that would counter this problem of vaccinated chickens harbouring the virus".
Dr. Stan Botchway of the STFC Rutherford Appleton Laboratory who developed the advanced microscopy technique and worked on the study said: "The type of microscopy we used to study the viruses interacting with the chicken cells is particularly valuable for several reasons. For example, by using near infra red laser light we are able to see deeper into cel