Charles Martin, (334) 844-9986 (firstname.lastname@example.org),
Mike Clardy, (334) 844-9999 (email@example.com)
DEVELOPS FIRST EGG-INJECTED POULTRY VACCINATION AGAINST AVIAN INFLUENZA
AUBURN - An Auburn University veterinary professor in collaboration with
researchers at Vaxin Inc. of Birmingham has developed the first in
ovo, or egg-injected, vaccine to protect chickens against avian
influenza, a virus threatening human health and global poultry populations.
Haroldo Toro, whose research is in press in the scientific journal, Vaccine,
says it would provide 100 percent protection once an outbreaks strain
We have proven the principle, which is the major step in leading
to commercially produced vaccine that could be vital to the poultry industry,
Toro said. When an outbreak occurs, we would determine the strain
and quickly create a vaccine within three months specifically for it.
The researchers inserted a gene from a low pathogenic avian flu virus
strain (H5N9) into a non-replicating human virus, a Vaxin proprietary
technology, which was then injected into developing chicken embryos still
in the egg. When protection induced by the vaccine was tested against
two highly pathogenic avian flu viruses, a Vietnam H5N1 strain and a Mexican
H5N2 strain, the results showed 68 percent and 100 percent protection,
These strains have slightly different genetic makeups which account
for the different percentages in protection, said Toro, who is also
collaborating on this project with the Southeast Poultry Research Laboratory
in Athens, Ga. Our results indicate that we can provide effective
protection against any strain after incorporating the gene of the field
strain into our vaccine construct.
The disease has decimated poultry populations in Asia in recent years.
Toro says United States health officials are continuously monitoring both
chicken flocks and migratory birds that might bring new, highly pathogenic
strains of the disease and infect poultry flocks, possibly killing between
90 to 100 percent in affected areas.
The current policy of health officials during an outbreak of highly pathogenic
avian flu is mass euthanasia and disposal of infected birds, and strict
biosecurity measures. Mass vaccination programs around the perimeter region
would help to reduce the risk of further dissemination of the field virus
to neighboring areas. Because this new vaccine also allows easy differentiation
between naturally infected birds and vaccinated birds, it could also be
used to prevent outbreaks of disease in case of immediate risk from a
known strain affecting, for example, neighboring countries.
We can vaccinate lots of birds in a quick, cost- and labor-saving
manner which otherwise would not be possible, Toro said. Most
poultry operations already have automated injection machines to vaccinate
against Mareks disease, injecting up to 40,000 eggs per minute.
Our vaccine is produced through cell cultures, so we can easily make enough
vaccine for thousands of birds.
He says this procedure is much easier than producing inactivated, or killed,
vaccines, which require replicating the live avian influenza virus in
egg embryos and individual delivery by injection. In addition, naturally
infected chickens cannot be differentiated from those vaccinated if the
strain used for vaccination is the same as the one acting in the field.
Currently available recombinant vaccines, using fowlpox vectors, are injected
into the chicken and have been shown to be less effective in birds pre-exposed
to the fowlpox vector. Pre-exposure to the vector used in this novel vaccine
is extremely unlikely in chicken populations.
Both of the current methods are difficult and labor intensive, and
are too time consuming, when time is critical, he said. The
in-egg vaccine is easy to produce, easy to administer and very effective.
He adds, The vaccine would, in turn, reduce the risk for human exposure
to avian influenza. Even though the risk to people is low, there
have been confirmed cases among humans reported since 1997, primarily
in Asia as a result of contact with infected chicken, ducks and turkeys.
Toros research is funded through a USDA program set up in 2004 for
universities to study avian influenza. The next step is gaining federal
approval to commercially produce the vaccine.
We are looking at two or three years for federal approval, but it
might be much sooner if an outbreak occurs, he said. We have
a very good tool against avian flu. No one has done this before.
Auburn University is a preeminent land-grant and comprehensive research
institution with more than 23,000 students and 6,500 faculty and staff.
Ranked among the top 50 public universities nationally, Auburn offers
more than 230 undergraduate, graduate and doctoral degree programs.
(Contributed by Charles Martin. Photos available on request.)