Immune Health Image
Immune health image

Immune Health

Understanding Immunosuppression

Immunosuppression is an industry threat worldwide, resulting in significant economic losses. Foundational immune health means providing poultry with early protection against the primary immunosuppressive diseases – most commonly Marek’s disease (MD)* and infectious bursal disease (IBD, also known as Gumboro disease)* in chickens – 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


The Impact of Diseases on Immune Health


The avian immune system has many components that help the bird fight infection: lymphoid tissues, the bursa of Fabricius, thymus, spleen, 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 disease 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 response to invading pathogens. The bursa is still under-developed when 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.


The cells associated with the cellular immune response are the T cells, which are released from the thymus. These cells are critical in the response to a number of diseases including Marek’s disease.


Marek’s Disease*


Marek’s disease is a herpesvirus-induced lymphoproliferative disease of chickens. In the 1960’s, Marek’s disease caused huge economic losses to the industry due to high numbers of leukosis condemnations at processing as well as widespread immunosuppressive effects leading to reduced performance. The virus causes transformation and proliferation of T cells, with clinical presentations including visceral or subcutaneous tumors, neuronal paralysis, and blindness due to lymphocyte invasion of the iris.


Clinical presentation of Marek’s disease varies greatly and may include peripheral paralysis, neurological signs, diarrhea, blindness, red legs, subcutaneous tumors, and visceral tumors. It is also a major cause of immunosuppression due to early viral replication occurring in both B and T lymphocytes. After initial viral replication and immunosuppression, the virus goes latent in T cells. Infectious particles can then be shed via viral replication in feather follicles and/or T cell transformation and proliferation, leading to invasion of the peripheral nervous system or tumor formation in any organ.


The virus falls into three serotypes depending on oncogenicity and natural hosts. Serotype 1 contains oncogenic field viruses and is further categorized by virulence including mildly virulent, virulent, very virulent, and very virulent+ categories. Serotype 2 includes non-oncogenic field viruses. Serotype 3 is the turkey herpesvirus (HVT), which is nonpathogenic in chickens. However, HVT is immune-stimulating and serves as the foundation of the Marek’s vaccine in short lived, meat type birds.

Serotype Characteristics

Serotype Characteristics Common Vaccine Strain

Serotype 1

Oncogenic field viruses

Rispens (CV1988)

Serotype 2

Non-oncogenic field viruses


Serotype 3

Non-oncogenic turkey herpesvirus


Infectious Viral Particles

Infectious viral particles are shed in bird dust and feather dander. The virus is extremely stable in poultry houses even after thorough disinfection. Due to the ubiquitous nature of the disease and its ability to induce crippling immunosuppression, early protection is critical. Most commercial birds are vaccinated at the hatchery either by subcutaneous injection at day-old or in ovo injection at 18-19 days of embryonation with HVT or an HVT recombinant.


The creation and implementation of Marek’s vaccination was revolutionary for the poultry industry. The control of the virus today still depends on vigilant vaccination of both breeding stock and production birds. Vaccine administration should always be an initial point of investigation when problems arise.


Infectious Bursal Disease*


One of the most common viral infections in chickens, infectious bursal disease (IBD), also known as Gumboro disease, is caused by the IBD virus, which destroys B lymphocytes in the bursa of Fabricius. Found worldwide, IBD mainly affects chickens up to 6 weeks old whose bursas are still under development. It can cause not only a variety of debilitating clinical signs but also an underlying immunosuppression that leads to poor growth and performance, with significant economic impact on the poultry industry.


The IBD virus is highly contagious to other chickens via their feces and, once established, can be very difficult to eradicate in farm and production settings. So while good hygiene practices play a role, vaccination is most important in disease prevention and control*, especially as IBD cannot be treated post-infection.


Viral strain diversity falls into three broad categories based on virulence, with varying clinical signs, mortality rates, and degrees of immunosuppression. The sub-clinical form of the disease does not cause any clinical signs but does depress growth and performance, increase susceptibility to other pathogens, and impairs the response to vaccines.


Because of the particular vulnerability of the developing bursa in younger birds, early protection is most important but can also present challenges. Newly hatched chicks possess maternal antibodies against IBD that decline over time but can interfere with some types of vaccines while still present.

Boehringer Ingelheim Solutions**

In recent years, new technologies, such as vector vaccines, have enabled simpler vaccination protocols developed around standardized hatchery administration. Our product portfolio includes a wide selection of vaccines of highly regarded efficacy and quality to help prevent and control the most important poultry immunosuppressive diseases. Some of our top product brands in this area (often available across multiple regions**) include:








To learn more about our vaccines, talk to your Boehringer Ingelheim representative.

We look forward to hearing from you.

BI Representative

Boehringer Ingelheim Animal Health USA Inc.
Poultry Business Unit
3239 Satellite Blvd. Duluth, GA 30096


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


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


1Atienza 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, p9. 

2Botero 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. 

3El 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. 

4Rautenschlein 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. 

5Herrmann 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. 

6Ochoa 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. 

7Tang 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. 

8Alonso 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.

9Devaud 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. 

10Lemiere 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. 

11Rautenschlein 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. 

12Trotel 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, p9 and p68-76. 

13El 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.


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