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MondaesMom

New West Nile Virus Vaccine

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Our vet is carrying a new single dose WNV vaccine. Within a few weeks, I intend to be vaccinating our 5 for the year since we are in a very prone area.

I hadn't heard about this before I stopped at the vet's the other day to make a payment on our account.

Now, I have a lot of confidence in our vet's belief in this single dose vaccine as he has up close and personal experience with WNV. I was just wondering if anyone else had heard about the new vaccine.

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Which vaccine are you talking about? PreveNile? Or the recombinant DNA vaccine? Neither are "new" per-se. The research seems to indicate that a single dose of the vaccine works. The only thing you're saving is a booster at the initial vaccination series. Instead of 2 vaccines 3 weeks apart, its just one. Then annual boosters, just like the other vaccines.

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They're carrying the Prevenile. I'm interested because then they would be on an annual schedule for their regular 5 way, rabies and the WNV vaccine.

Also, despite the making sure the booster is done w/in six months, etc, as recommended here, I still sweat it out until the 2 week period after the booster has passed b/c on our schedule that's usually when the virus really takes hold here.

We live right near the Columbia with the slough and all its inherent bugginess. I've seen mosquitos as early as March and as late as October here. So, we've got a fairly long season for being north of the 45th parallel.

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I don't trust it~!!!

When they first came out with W. Nile virus vaccine it was supposed to protect for a year.

I lost a 10,000 dollar Rocky Mountain Horse 8 months after he'd gotten the vaccine. A few weeks later they said you needed to start giving it every six months.

Too freakin late for my horse. I don't trust them, don't give a crap what they say, I'm getting it every 6 months. I was getting it every 4 months after my Rocky died because I didn't even trust it to be effective for the 6 months.

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Oh, great, I so didn't want to hear that story, Manes. Way to feed my paranoia.

[smiley Wavey]

You know what happened with my 5 way this past year, right? Two of the Arabs and the Morgan/Hereford mare were vaccinated in April near their actual birthdays and the Arab mare and Morgan mare both came down with Rhino in September.

That didn't help with the whole vector/bacterial/viral paranoia. [surrender]

Edited by MondaesMom

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Single-Dose WNV Booster Effective for Pregnant Mares (AAEP 2009)

by: Christy West

February 01 2010, Article # 15732

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When we only had one vaccine for West Nile virus (WNV) in horses, vaccination was quite simple. Then when different types of vaccines came along, the waters got a little muddier, especially for pregnant mares in which breeders feared risking not one, but two equine lives with new vaccine technologies.

At the 2009 American Association of Equine Practitioners Convention, held Dec. 5-9 in Las Vegas, Nev., a study discussed the efficacy of using a chimera West Nile virus vaccine to booster immunity in mares previously immunized against West Nile virus. The chimera vaccine used in the study, Prevenile, is made by replacing structural genes of the human yellow fever vaccine virus with those of the West Nile virus. The immune system acts against the West Nile virus proteins just like in a wild-type infection, but the chimera can safely replicate in the horse, producing a strong, protective immune response.

"When reviewing the literature, there was no clear evidence that this type of vaccine would be efficacious to booster pregnant mares (although in previous vaccine licensure studies, no adverse events were reported in pregnant mares)," said presenter Joseph Manning, DVM, of Equine Sports Medicine in Weatherford, Texas.

Lead author Cynthia V. Gutierrez, DVM, equine technical services veterinarian for Intervet/Schering-Plough Animal Health, reported the study had three objectives:

?To see if pregnant mares with low antibody levels (titers) had at least a four-fold increase in these levels after boostering;

?To see if high-titer mares had antivector immunity to this modified-live vaccine (to see if circulating antibodies inactivated the vaccine); and

?To confirm that this vaccine can be used as a pre-partum vaccine to induce colostral immunity.

The researchers boostered 81 previously vaccinated mares four to eight weeks before foaling with one dose of the chimera vaccine, according to the label instructions. After 14 days the mares all showed a four- to eight-fold increase in antibody titers, thus the vaccine was not inactivated and the boosted immunity would also increase colostral immunity (immunoglobulins in the mare's first milk or colostrum, which will help protect the foal against the disease).

No adverse events were seen as a result of vaccination, and all mares delivered live foals.

"The take-home message is that vaccinating primed pre-partum broodmares with a single dose of a West Nile virus chimeric vaccine does produce a titer rise (increased immune response) and can be used to boost colostral antibodies," the authors summarized.

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Merial Introduces Next Generation Equine West Nile Virus Vaccine

by: Press Release

January 06 2004, Article # 4887

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Merial announced today the release of a new equine vaccine--RECOMBITEK Equine West Nile Virus (WNV) vaccine. The recent USDA approval of RECOMBITEK Equine West Nile Virus vaccine offers veterinarians a first-of-its-kind product backed by cutting-edge science to offer fast-acting and long-lasting protection from the often deadly WNV. (Click here for an earlier article on the vaccine.)

"The RECOMBITEK West Nile Virus vaccine uses recombinant DNA technology to stimulate a fast, multifaceted and long-lasting immune response proven by natural mosquito challenge of West Nile virus," says Mike Murray, DVM, MS, Merial Equine Technical Director for Strategic Development. "The fast-acting immune response was demonstrated in a controlled trial that showed horses were protected from viremia caused by West Nile virus infection when challenged as early as two weeks after completion of the two-vaccination series."

The benefits of recombinant vaccine technology include a fast, multifaceted (humoral and cell-mediated) immune response, targeted antigen presentation, and a level of safety inherent to this technology due to the fact that there is no possibility of live virus replication.

As a leader in recombinant DNA technology, Merial manufactures and markets 11 of the 12 companion animal and equine vaccines that use recombinant DNA technology worldwide, including RECOMBITEK vaccines for dogs, PUREVAX for cats, and in Europe, PROTEQFLU, which induces rapid and long-lasting immunity to equine influenza.

"Recombinant technology vaccines have an intrinsic safety factor because animals receiving the recombinant vaccine are never exposed to the disease-producing organism," Murray says.

In 2002, WNV exploded throughout the U.S. equine population, resulting in 15,257 documented cases. The USDA estimates a mortality rate of approximately one third* of horses showing clinical signs of WNV disease. Although the total number of cases in the United States declined in 2003, WNV presented itself in various geographic regions, including a five-fold increase in clinical cases reported in the Mid-Atlantic states, demonstrating that this disease remains dangerous and unpredictable.

Merial is a world leading innovation-driven animal health company, providing a comprehensive range of products to enhance the health, well-being, and performance of a wide range of animal species. Merial operates in more than 150 countries worldwide. Its 2002 sales were in excess of $1.7 billion. Merial Limited is a joint venture between Merck & Co., Inc., and Aventis, S.A. For more information, please see www.merial.com.

*aphis.usda.gov web site, "Questions & Answers About West Nile Virus" (March 2003), Accessed Dec. 16, 2003, at: www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/faq_ahwnv.html.

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New West Nile Virus Vaccines for Horses Approved

by: Kimberly S. Brown, Editor

November 23 2009, Article # 15334

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New equine West Nile virus vaccines have been approved by the USDA. The vaccine line, called Vetera, is manufactured by Boehringer-Ingelheim, a privately held pharmaceutical company.

The Vetera line of West Nile virus vaccines "is the first new approach to a killed West Nile virus vaccine since 2001," stated Bob Stenbom, DVM, associate director of Equine Professional Services for Boehringer-Ingelheim.

There are three new vaccines in the Vetera West Nile virus line. The first is a monovalent that contains only a vaccine against West Nile virus. The second combines West Nile virus vaccine with Eastern equine encephalitis (EEE), Western equine encephalitis (WEE), and tetanus. The third vaccine combines all of the aforementioned plus Venezuelan equine encephalitis (VEE).

"We have color-coded the packaging and the vaccine bottles to help veterinarians quickly pick the correct vaccine from their supply," said Marion Tittle, senior brand manager for equine.

The technology used to make the new Vetera line of vaccines is unique in several ways. Stenbom noted that Vetera uses a different strain of the West Nile virus.

"We've seen a lot of changes in the genetic makeup (of the virus) since West Nile virus first entered this country in 1999," he noted. "The original strain of WNV (NY99) had a slow transmission. Then we saw a more rapid transmission as the virus made its way down the East Coast and through Florida and across the country. Genetic research since that time has shown it was a new strain (WN02) that did a much better job infecting mosquitoes and surviving in the environment. Vetera WNV vaccines incorporate an equine origin WNV strain (E159), representative of the more recent WNV strains impacting horses today."

He said all other West Nile virus vaccines on the U.S. market are based on the NY99 strain.

The second unique technology used in creating the Vetera line of vaccines is Ultrafil purification technique.

"You will hear a lot about this in the future," stated Stenbom. "Efficacy with few post-vaccination reactions is the goal of every vaccine. Extraneous proteins in vaccines from cell cultures and nutrients used in cell culture (used to grow the initial virus to make the vaccine) may cause problems with systemic vaccination reactions. Those reactions are not always caused by the desired vaccine components."

"Extraneous proteins should be filtered out as completely as possible from the finished vaccine to allow the immune system to remain 'undistracted' by irrelevant antigens," said Stenbom. "Ultrafil purification is a patent-pending process that allows optimal antigen loads in minimal dosage volumes and decreases the risk of post-vaccination reactions."

The third unique technology used in manufacturing Vetera is the Carbimmune adjuvant system that was developed about 10 years ago when Boehringer-Ingelheim used it in creating Calvenza equine influenza vaccines.

Adjuvants enhance the immune response to vaccine antigens. "Carbimmune adjuvant contains no sensitizing material of plant or animal origins," noted Stenbom. "It's a safe, flexible adjuvant system that is effective with a variety of antigens."

Stenbom explained that Carbimmune has the potential "to elicit higher levels of humoral antibody and cellular immunity than conventional aluminum hydroxide-based adjuvant systems."

He said Carbimmune acts like a sponge, so the antigens are dispersed on the surface and are drawn into the matrix of the molecule. The antigens on the surface of the Carbimmune matrix are available immediately when administered to give rapid onset of immunity. Then the "trapped" antigens deeper in the matrix offer a slow release of antigen that provide a longer duration of immunity.

The final piece of technology employed in the new Vetera vaccine line was how the vaccine was challenged with the intrathecal challenge model.

"Intrathecal challenge is considered to be the 'gold standard' for West Nile virus efficacy studies and the most aggressive challenge model," stated Stenbom.

The company noted that, according to information published by the American Association of Equine Practitioners in their "Guidelines for the Vaccination of Horses," the mosquito and needle challenge were the two models used in early West Nile virus studies. These methods resulted in only 10% of unvaccinated (control) horses showing signs of clinical disease when challenged. More recently, however, the intrathecal challenge model has been used, resulting in 90% to 100% of unvaccinated control horses developing grave signs of encephalomyelitis.

The name of the vaccines were derived because Boehringer-Ingelheim only sells vaccines to veterinarians (Vet-) and this new approach to creating equine vaccines launches a new era (-era) "in how equine vaccines should be made," Tittle said.

For more information ask your veterinarian or visit Vetera-Vaccines.com.

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Two of the Arabs and the Morgan/Hereford mare were vaccinated in April near their actual birthdays and the Arab mare and Morgan mare both came down with Rhino in September.

Well, in all honesty that wouldn't surprise me much....The immunity garnered from vaccinating for Rhino & Flu is notoriously short-lived, which is why some recommend vaccinating at-risk horses (heavily showing, lots of travelling, etc) up to 4 times per year. Also the reasoning behind vaccinating pregnant mares with Pneumabort-K (Herpesvirus vaccine, which is "Rhino") every 2 months.

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Wow, my info is really out of date. I'd always thought that things like vaccination technology was pretty static. I'm learning that it isn't.

I think I'm off to puruse the vet school websites for more info.

Thanks, cvm and all!

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My gelding, Willy, was vaccinated with the first WNV vaccine that came out after the first outbreak in NYC, where we reside. His boosters were kept up to date, but he ended up getting WNV anyway a few years back. Thank the Lord it was a pretty mild case and he recovered, but lost an eye in the process. Since the newer vaccines (once a year) came out, our stable switched to - I believe - Prevenile. Viruses, unfortunately, mutate all the time, so what works now, may not fully work next year. So far, I have still been vaccinating Willy - even tho some in the medical community think that there is lifelong protection if they come down with the disease. Since WNV can mutate, the horse needs to be reboostered annually. [Duh]

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