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Feedstuffs, August 23, 2010
Nutrition & Health: Swine
‘Fusion strategy’ may
S
OUTH Dakota State University
researchers are exploring a
“fusion strategy” for making
improved vaccines to protect pigs
and people against enterotoxigenic
Escherichia coli strains (ETECs).
Weiping Zhang, an assistant
professor in the university’s
veterinary and biomedical sciences
department, is leading the group
that altered the toxins produced
by ETECs and genetically fused the
non-poisonous “toxoid” to a protein
known to cause an immune reaction.
The resulting “fusion protein” could
be used to develop a vaccine, Zhang
said.
Besides causing diarrheal illness
in farm animals, ETECs are the main
source of bacterial-caused diarrhea in
the developing world.
The research is one of the ongoing
projects in South Dakota State’s
Center for Infectious Disease
Research & Vaccinology, which looks
for new ways to diagnose and treat
infectious disease in people and
domesticated animals.
The ETEC project is innovative in
that for vaccine components, it uses
the toxins scientists call “heat-stable
enterotoxins” that are generally
harmful to animals and people
and remain active even in at the
temperature of boiling water.
Zhang said heat-stable enterotoxins
can’t be used directly as a vaccine
component because of their toxicity
and because they are poor at causing
an immune response unless coupled
to a carrier protein. That’s why many
vaccine researchers working with
ETECs focus on other disease-causing
elements — the so-called heat-labile
enterotoxins that are destroyed at
high temperatures and the fimbriae
(appendages) that help the bacteria
hold onto the host.
However, Zhang said not including
heat-stable enterotoxins as a
vaccine component poses a problem
because more than two-thirds of
Research
with
TIM LUNDEEN
ETEC diarrhea cases in people
and more than one-fourth of ETEC
diarrhea cases in pigs are caused by
ETECs that produce a heat-stabile
enterotoxin called STa.
“STa antigens must be included for
developing broadly effective vaccines
against ETEC infection,” Zhang
explained.
He noted that because the heatstable enterotoxins are toxic, “we
cannot use them directly, (but) we
mutated a gene. We only changed
one amino acid for each toxin. That
change shifted them from toxic to
nontoxic.”
In the same way, the research group
mutated a gene that produces a heatlabile enterotoxin known to produce
an immune response. They then fused
the two mutated toxoids to produce a
fusion protein.
By tweaking only a few amino acids,
the researchers said they left the
protein structure of the bacterium
largely intact.
That is important, Zhang said,
because just as the toxin has to bind
to a receptor in the small intestine
in order to cause the disease, the
vaccine component must bind to that
same receptor in order to cause an
immune response.
Zhang and his colleagues published
the fusion strategy research in
January in the journal Infection &
Immunity. Zhang’s co-authors were
Chengxian Zhang, David H. Francis,
Ying Fang and David Knudsen of
South Dakota State, James Nataro of
the University of Maryland School of
Medicine and Donald C. Robertson of
Kansas State University.
The researchers are currently
studying five possible vaccine
components using the pig model.
Once they’ve selected the best
vaccine component, they’ll move on
to larger lab trials and field trials, the
announcement said.
Zhang said the possibility of an
improved swine vaccine is important
because some estimates are that
swine producers lose $80 million a
year due to illness in pigs in North
America alone.
Meanwhile, since the ETEC toxins in
pigs and people are nearly identical,
Zhang and his colleagues are using
the same system to explore a possible
human vaccine.
Zhang added that if the research
leads to an improved vaccine, the
entire process of developing the
vaccine will take about 10-15 years.
Swine disease project
The Iowa Pork Producers Assn. (IPPA)
and the Iowa State University College
of Veterinary Medicine are taking
steps to address a reproductive
and respiratory disease that has
circulated in swine herds for the past
20 years.
IPPA and Iowa State are proposing
to establish a porcine reproductive
and respiratory syndrome (PRRS)
control project in Iowa County
(southwest of Cedar Rapids, Iowa).
PRRS has been called the most
In 60 seconds
used in the dairy feed industry but has
application in all feed markets.
Swine starter: Hubbard Feeds
Inc. has introduced PowerStart, a new
two-phase starter program designed for
pigs weaned at 19 days or older. The
product line includes three cost-effective
formulations designed to meet the nutritional needs of pigs at various weaning ages: PowerStart 19/13, PowerStart
25/16 Complete and PowerStart 25/16
Basemix.
Sales agent:
Reproductive care: Van Beek
Natural Science has introduced UterFlush, a liquid product for reproduct i v e care in beef and
dairy cattle.
Gut inflammation:
UterFlush
contains essential
oils with antimicrobial properties that
maintain and restore the normal uterine
environment. UterFlush is administered
intrauterinely post-calving to help restore
the cow’s uterus to normal as quickly as
possible. It can be given immediately
after calving or later on when problems
arise. The flush also can sustain the
cow’s reproductive performance, reducing the breed-back time frame. A natural
foaming agent from yucca helps the
UterFlush reach all areas of the uterus.
UterFlush is available in a 30 mL syringe
that has a dial to ensure that the accurate amount is expelled when mixing the
product.
Yeast extract: Western Yeast Co.
has developed MOS-CON, a combination of concentrated live yeast culture
and concentrated yeast extract. The
product has 1 billion colony forming
units of Saccharomyces cerevisiae and
is mixed at the rate of 2-3 lb. per ton of
feed or top dressed to individual animals at the rate of 0.5 oz. per head per
day. It has application where customers
want a high-cell count yeast culture plus
mannan oligosaccharides, the company
said, noting that it is currently being
Milk Products
announced that it has been named
national sales agent for Bovidr Laboratories. Milk Products now will distribute
Nutri-drench and Nutri-drops products
through feed manufacturers, retailers
and wholesale distribution. Nutri-drench
and Nutri-drops are liquid energy supplements fed to animals off-feed and in
stress situations.
R&D LifeSciences LLC (R&DL) announced the
introduction of ReNuvigen, its new
feed-grade inflammation management
product. Available in 50 lb. bags, the
feed-through solution is designed to
reduce chronic gut inflammation and
improve various production parameters
in food-producing animals. ReNuvigen
egg globulin protein stops the initiation
of chronic inflammation before it affects
the animal’s nutrient digestion, absorption and utilization. According to Dr.
Dave Cook, R&DL director of technical services, “Data have shown better
feed conversion, daily gains and overall
immune status success when fed to various production animal species, including
beef and dairy calves, swine, poultry
and aquaculture.”
Dairy leadership: The Cornell
Dairy Executive Program is now accepting applications for its next class, which
will begin in December. This educational
opportunity, organized by the PRODAIRY Program at Cornell University,
is designed to provide progressive dairy
executives and agri-service personnel
with the opportunity to increase the leadership and management skills necessary to run a successful business. Timely topics in dairy business management
will be presented by a team of national
experts from within and outside the field
of agriculture. More information and an
application can be found at www.ansci.
cornell.edu/prodairy/dairyexec. The
class size is targeted at 30 participants.