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Our Immune Foundation Approach


Dr. Stephane Lemiere is Merial’s Global Technical Director of Avian business and an industry-recognized expert in avian health and immunology. He oversees our Veterinary Services group and Merial Vaccination Technologies and Services (VTS), who partner with our customers to develop and execute effective vaccination programs. Dr. Lemiere has been with Merial since 1993, helping establish and define our immune foundation approach to poultry vaccination, and here he discusses this concept and how it shapes our vaccination strategies.


Can you start by giving an overview of the “immune foundation” concept?

Simply put, it means providing poultry birds with very early protection against the main immunosuppressive diseases—the most common ones in chickens being Marek’s disease* and infectious bursal disease (IBD, also known as Gumboro disease)*—in order to allow their immune systems to thrive and reach full potential. Numerous studies have shown that when chickens start life with a strong immune system, everything that follows is better: their overall health, resistance to infection, uptake of other vaccines, growth and productivity.1-13


How do these diseases affect chickens’ immune systems?

The avian immune system has many components that helps the bird fight infection—such as lymphoid tissues, the bursa of Fabricius, thymus, spleen, lymphoid tissues associated to mucosae, and cellular effectors, mainly B and T lymphocytes, as well as other white blood cells, like macrophages, heterophils, natural killer cells, or dendritic cells. The Marek’s and IBD viruses attack lymphocytes, subsequently suppressing aspects of the bird’s immune functions.

The bursa of Fabricius is a unique, specialized immune organ in birds that plays an essential role in developing B cells and antibodies in respond to invading pathogens. The bursa is still under-developed when new chicks hatch—it continues to develop and serve its role during the first 10-15 weeks of a bird’s life. The IBD virus attacks the bursa, destroying B cells and damaging bursal function.

More on our approach to Marek’s Disease

More on our approach to Infectious Bursal (Gumboro) Disease

Both these diseases cause various clinical signs and mortality, but even birds that do survive infection remain irreparably immunosuppressed, impairing their ability to fight off future infections. So preventing these two diseases in the poultry industry is critically important to ongoing flock health and productivity.1-13

“Both IBD and Marek’s disease can infect birds sub-clinically—so even in the absence of clinical signs, the diseases can cause an underlying immunosuppression that adversely affects productivity.”


What about customers who say IBD and/or Marek’s are not a threat in their area, or not a vaccination priority for them?

The fact is, both of these viruses are endemic in every region of the world. If they’re perceived as not a threat, it’s likely because they have been so successfully controlled by effective vaccination protocols. In addition, both IBD and Marek’s disease can infect birds sub-clinically —so even in the absence of clinical signs, the diseases can cause an underlying immunosuppression that adversely affects productivity. Low weight gain in broilers, poor feed conversion, and reduced egg production in layers can all result from sub-clinical disease—not to mention greater susceptibility to secondary infections like E. coli.

We recognize that our customers are under tremendous pressure to produce more food, more cost-effectively—and that other diseases are sometimes a higher priority for their health care budgets. But we can show data from clinical research and field trials demonstrating how a strong immune foundation has translated to improved productivity in commercial poultry flocks.1-13 When applying our immune foundation approach, Merial’s Veterinary Services team partners with each customer to develop a vaccination program that aligns with their specific priorities and business goals.


Does that mean Merial’s immune foundation approach is primarily about disease prevention?

No, that’s really only one aspect of it. We consider the immune foundation to have four pillars:

1. Protection against the main immunosuppressive viral threats already mentioned—IBD* and Marek’s*1-13

2. Early protection, while the immune system is still under development, and before birds begin being more widely exposed to threats4, 14

3. Early stimulation of various immune mechanisms, which may help optimize their function; for example, we are currently investigating how this may help activate the innate immune system11, 13

4. Vaccination in breeder birds strategically timed to pass on appropriate levels of maternally inherited antibodies to progeny, giving them what we call “passive immunity”—a short-term but important component of immune protection for many diseases15-20

Collectively, these pillars form a solid immune foundation that helps commercial poultry birds thrive through the duration of their production life cycle.


What’s the best way to establish this solid immune foundation?

Our immune foundation philosophy is reflected in Merial’s avian vaccine portfolio** of industry-leading solutions to protect against IBD and Marek’s disease. In most cases, we recommend a program based around our globally marketed*** flagship product VAXXITEK® HVT + IBD as a starting point. It uses vector technology to protect against two diseases in one vaccine: Marek’s (serotype 3) with the non-pathogenic HVT virus, which also functions as a vector to carry protection against IBD. This is a hatchery-administered vaccine (injected either in-ovo at transfer between setter to hatcher, or sub-cutaneously to day-old chicks), which means protection is initiated as early as possible. Since the launch of VAXXITEK HVT + IBD in 2006, we’ve compiled extensive scientific evidence on its efficacy, safety, and role in our immune foundation approach—these publications form the basis of our decision-making1-13.

Learn more at our VAXXITEK HVT + IBD website

Merial’s comprehensive product portfolio also includes a range of vaccines to cover other Marek’s serotypes (1 and 2), which are necessary to round out a complete vaccination program for longer-lived layer and breeder birds, as well as other select IBD vaccines to offer flexibility to our customers.21

“Early protection is a fundamental part of the immune foundation—and the hatchery affords the earliest opportunity to vaccinate!”

Is the immune foundation contingent on hatchery vaccination?

Generally speaking, yes. Early protection is a fundamental part of the immune foundation—and the hatchery affords the earliest opportunity to vaccinate! With today’s vaccine technologies, we can vaccinate chicks at one day of age, or even while still in ovo. The hatchery provides a well-controlled, biosecure environment to administer vaccines before birds start being more widely exposed to pathogens, and while their immune systems are still developing and thus most receptive to stimulation.

Hatchery techniques also allow greater precision than mass vaccination on the farm—precision that’s important for achieving good coverage for these particular vaccines. Merial’s VTS teams are experts in hatchery vaccination practices—they develop innovative equipment, train staff on using it, and even help producers transition their operations to hatchery administration, all to ensure successful execution of an immune foundation program.

That said, we understand that not all Merial’s customers around the world are able or ready to implement hatchery vaccination. So our Veterinary Services group works closely with each business on customized vaccination programs to optimize flock health and productivity within the realities of their operations.


Does everyone in Merial’s Avian group promote the immune foundation approach, in all regions of the world?

Absolutely! Immunosuppression is an industry threat worldwide, causing significant economic losses. We believe strongly that the immune foundation is a truly universal principle of poultry health, regardless of geography. Merial’s scientists and vets are well-regarded experts in poultry immunosuppressive diseases. Building on our legacy as one of the historical pioneers in Marek’s disease vaccination, as well as the technological innovations of VAXXITEK HVT + IBD, we’ve been taking this immune foundation approach to avian health and our avian business for more than 20 years. Of course, the details of any poultry vaccination program must be customized to local conditions and specific business needs, but the goal of a strong immune foundation is always our starting point.

Every new person who joins our team is trained in this philosophy—and it’s the expertise and services of our people that drive its successful implementation. We’re deeply passionate about avian health, actively researching, publishing, and sharing our findings to help the poultry industry move forward. Our teams love to talk with customers—whether the vets or the business people—about the science behind our products, programs, and services. We invite our customers to contact us at any time to discuss the immune foundation, or any other aspect of avian health.


 *Merial produces and markets several vaccines against infectious bursal (Gumboro) and Marek’s diseases. However, be aware that NOT all aspects of the diseases mentioned on this page are addressed by a vaccine. Always consult the product label for exact vaccine indications.

**Many of Merial’s avian vaccines are only marketed and available in certain countries, sometimes under different trade names. Speak to your Merial representative or contact us to find out what’s available in your region.

***A vaccine product sold under the VAXXITEK® HVT + IBD trade name is available in more than 75 countries worldwide.


To find out exactly which Merial avian products and vaccination equipment options are available in your region, talk to your Merial representative or contact us now.

Top Avian Health Concerns



1. Atienza JC, Nagera AJ, Martinez PO, Baysac ND, Castillo MT, Damaso VR, Lemière S. Evaluation of a herpesvirus of turkey vector vaccine inducing protection against infectious bursal and Marek’s diseases (VAXXITEK® HVT+IBD) under Philippines field conditions. Oral presentation. XXIII World Poultry Congress, Brisbane, Australia. 2008. Article wpc0801684, 9p.

2. Botero LA, Fernandez R, Rojo F, Orrego JC, Lemiere S. Colombian chicken meat industry performance further to the use of VAXXITEK HVT+IBD vector vaccine. Oral presentation. 16th congress of the World Veterinary Poultry Association, Marrakesh, Morocco, 2009; p169.

3. El Houadfi M, Cluzel B, Rawi T. Does VAXXITEK® HVT+IBD vector vaccine improve antibody response to ND vaccines? Abstract. 16th congress of the World Veterinary Poultry Association, Marrakesh, Morocco, 2009.

4. Rautenschlein S, Simon B, Jung A, Pöppel M, Prandini F, Lemiere S. Protective efficacy of VAXXITEK HVT + IBD in commercial layers and broilers against challenge with very virulent infectious bursal disease virus. 16th congress of the World Veterinary Poultry Association, Marrakesh, Morocco, 2009.

5. Herrmann A, Negm H, Sultan H. Turkey herpesvirus infectious bursal disease (HVT-IBD) vector vaccine – Field experience in commercial broilers in Egypt. Article. XVIIth Congress of the World Veterinary Poultry Association, Cancun, Mexico, 2011; p556-563.

6. Ochoa R. Monitoring of safety and efficacy of a herpesvirus turkey-infectious bursal disease (HVT-IBD) in a commercial layer operation in Mexico. Article. XVIIth Congress of the World Veterinary Poultry Association, Cancun, Mexico, 2011; p770-774.

7. Tang SF, He SJ, Li WM, Lemiere S. Field experience of vaccination in day-old broiler chickens with a herpesvirus turkey-infectious bursal disease (HVT-IBD) vector vaccine in different systems of chicken production across China. Poster presentation. XVIIth Congress of the World Veterinary Poultry Association, Cancun, Mexico, 2011; p920-926.

8. Alonso Castro M, Merino Cabria D, Fernandez Garcia D, Torrubia Diaz J, Herreras Viejo R, Fernandez Revuelta J, Mateo Oyague J, Carvajal Uruena A. Evaluation of the effects of vaccination with a HVT-IBD vector vaccine on bursa Fabricii, production parameters and meat properties in broilers. Abstract. XVIIIth Congress of the World Veterinary Poultry Association, Nantes, France, 2013; in-press.

9. Devaud I, Herin JB, Trotel A, Pagot E, Voisin F. A field study in commercial layers to evaluate the effects of an HVT-IBD vector vaccine on production performances in comparison with a live IBD vaccine. Abstract. XVIIIth Congress of the World Veterinary Poultry Association, Nantes, France, 2013; in-press.

10. Lemiere S, Rojo R, He S, Tang S, Li W, Herrmann A, Prandini F. Benefits of the Herpesvirus of Turkey vector vaccine of Infectious Bursal Disease in control of immune-depression in broilers and decrease of use of antibiotic medication. Abstract. XVIIIth Congress of the World Veterinary Poultry Association, Nantes, France, 2013; in-press.

11. Rautenschlein S, Lemiere S, Prandini F. Evaluation of the effects of an HVT-IBD vector vaccine on the immune system of layer pullets in comparison with two commercial live IBD vaccines. Abstract. XVIIIth Congress of the World Veterinary Poultry Association, Nantes, France, 2013; in-press.

12. Trotel A, Herin JB, Devaud I, Pagot E, Adamczyk E, Voisin F. Comparison of two IBD vaccinations in laying hens: benefit on growth, homogeneity of vaccination and production performances. Revue de Medecine Veterinaire; 2014, Vol. 3/4, p68-76, 9p.

13. El Garch H., Moulian N., Frecon F., Hanotel E., Delvecchio A., Lemière S. Cellular immune mechanisms after in ovo vaccination with a HVT-IBD vector vaccine. Presentation and abstract at the 19th congress of the World Veterinary Poultry Association, Cape Town, South Africa, 2015.

14. Bublot M, Pritchard N, Le Gros F-X, Goutebroze S. Use of a vectored vaccine against infectious bursal disease of chickens in the face of high-titred maternally derived antibody. Journal of Comparative Pathology, 2007;137:81-84.

15. Montiel E, Pritchard N, Cruz-Coy J, Katigbak E, Smith D. Efficacy and Seroconversion of Various IBD Vaccination Programs in Broiler Breeders: Seroconversion and IBD Progency Challenge Results. Presentation. American Association of Avian Pathologists, New Orleans, Louisiana, 2008.

16. Montiel E. Vaccination of broiler breeders against infectious bursal disease: seroconversion, progeny protection and impact of breeder revaccination with live vaccines. Oral presentation. 16th congress of the World Veterinary Poultry Association, Marrakesh, Morocco, 2009; p220.

17. Montiel E, Pritchard N, Cruz J, Katigbak E, Wilcox M, Wilson J. Vaccination of broiler breeders with a herpesvirus of turkeyinfectious bursal disease virus (IBDV) vector vaccine: seroconversion and progeny challenge studies. Abstract. American Association of Avian Pathology Symposium, Atlanta, United States of America, 2010; p102.

18. Montiel E, Pritchard N, Lemiere S, Wilson J. Use of a Vector HVT+IBD vaccine in broiler breeders. Paper presented at 9th International Congress on Marek's Disease; Berlin, Germany, June 2012.

19. Lemiere S, Gauthier J.C., Kodjo A., Vinit L., Delvecchio A., Prandini F. Evaluation of the Protection against Infectious Bursal Disease (IBD) Challenge in Progeny Born to Parents Having Received a Vaccination Program Using Herpesvirus of Turkey-Infectious Bursal Disease (HVT-IBD) Vector Vaccine. World J. Vaccines, 2013; 3:46-51.

20. Parker D, de Wit S. Assessment of impact of a novel infectious bursal disease (IBD) vaccination programme in breeders on IBD humoral antibody levels through the laying period. Veterinary Record Open 2014 Jun 25;1(1):e000016.

21. Lemiere S, Wong YS, Saint-Gerand AL, Goutebroze S, le Gros FX. Compatibility of Turkey Herpesvirus–Infectious Bursal Disease Vector Vaccine with Marek’s Disease Rispens Vaccine Injected into Day-Old Pullets. Avian Dis., 2011; 55:113-118.