Pathogenesis and improved diagnosis and control of
avian influenza infections
Time of action: AVIFLU started in October
2002, ended in September 2005 and has been extended for another
12 months until September 2006
EU budget (funding): € 1.8 million
In recent years, several vaccines have been developed against
highly pathogenic avian influenza virus (HPAI) in poultry.
Their use has shown that vaccination can protect chickens
from developing disease symptoms and dying from infection.
Yet outbreaks of HPAI are still controlled by killing infected
animals as it is not known whether vaccinated poultry could
‘silently’ spread the disease, increasing the
risk of new outbreaks and posing a serious threat to humans.
Until recently, little was known about how HPAI was transmitted
in chickens, or how vaccines reduced transmission. But as
part of the AVIFLU project, researchers have been able to
quantify the effects of vaccination on transmission dynamics.
They have shown that two commercially available vaccines against
H7 subtypes not only protect chickens against mortality and
morbidity, but also reduce the spread of the virus within
a flock to such an extent that a major outbreak can be prevented.
However, the scientists also found that vaccination does not
appear to block viral transmission completely, so some slaughtering
may also be necessary.
The main aim of the AVIFLU project is to improve the diagnosis
and control of avian influenza. The partners have looked at
the pathogenesis of avian influenza in different species and
the molecular mechanisms of susceptibility. They are also
investigating new diagnostic methods (based on the detection
of antigens, RNA and/or antibodies). The researchers have
conducted two ring trials with the aim of determining the
most sensitive, robust, specific, etc. RT/PCR. As a result,
real time RT/PCR and conventional RT/PCR protocols for the
generic detection of AI and for the specific detection of
H5 AI have been identified. The best protocols have now been
recommended to the AI labs in both the EU member states and
the non-EU countries. They will also be included in the new
EU Diagnostic manual.
Status (January 2006)
When the partners on the AVIFLU project first got together
to draft their proposal, little did they know how numerous
outbreaks of HPAI – most recently that of the H5N1 subtype
– would change the course of their work. The project
was due to finish in September 2005, but has now been extended
for a further 12 months. This will enable the researchers
to conduct additional experiments to assess the role that
waterfowl may play in the epidemiology of the H5N1 outbreak
They are studying the efficacy of one commercial vaccine
to protect ducks against clinical disease and prevent transmission
of the virus. Preliminary results are encouraging, suggesting
that Europe may need to consider implementing prophylactic
vaccination programmes to protect against the inevitable arrival
Dr Jill Banks
Department of Environment, Food and Rural Affairs
Veterinary Laboratories Agency
Surrey KT15 3NB