Immunosuppression can have many causes, including disease-related causes, due viruses such as the chicken anaemia virus, Gumboro or Marek’s disease. ‘Control of these diseases at an early stage will not only help poultry build resistance against other diseases and secondary infection but also allows for a better vaccine take,’ explains Dr Stephane Lemiere, Global Director of Technical Services at Boehringer Ingelheim VetMedica.

Two major immunosuppressive diseases

Infectious bursal disease (IBD) and Marek’s disease (MD) are two major immunosuppressive diseases, affecting poultry worldwide. IBD (also known as Gumboro), first described in the 1970s, is a highly contagious viral infection in chickens with a huge economic impact due to increased susceptibility to other diseases. The target organ of the virus is the bursa of Fabricius, and marked bursal atrophy and lymphoid depletion are typical for the disease.

Different pathotypes exist: Classical and vvIBD strains are responsible for most cases of clinical IBD, causing a sudden onset of disease and a rapid spread, with a morbidity of up to 100%. Field infections cause drowsiness, muscle haemorrhage, bursitis and death. Certain classical and variant IBD strains are associated with subclinical IBD. A weakened immunity means that secondary infections such as colibacillosis and gangrenous dermatitis may appear. Mortality is common in susceptible flocks, and infected birds become carriers and shedders of the virus.

Marek’s disease (MD) is a herpesvirus infection that can cause tumours and lesions due to the malignant transformation of the CD4+ lymphocytes, leading to immunosuppression. Clinical signs vary according to the affected tissue, but nervous lesions such as paralysis are frequently seen. Condemned carcasses and egg drop are also common consequences. Mortality can reach 100%. The virus is spread in dander from feather follicles and transmitted by inhalation. Infected birds become carriers and shedders of the virus for life. The disease occurs worldwide and has a high resistance to environmental conditions and disinfectants. Marek’s disease affects broilers, layers, breeders and turkeys. Over the past decades, the MD virus has become increasingly virulent and immunosuppressive (fig. 1).

Fig 1. Over the past decades, the MD virus has become increasingly virulent and immunosuppressive.

Early prevention is essential

It is essential to prevent these immunosuppressive diseases by early vaccination. But which vaccine to choose? Dr Lemiere sums it up: ‘The ideal vaccine should provide a broad protection against both diseases and immunosuppression, thereby preventing poor vaccine take, secondary infections and decreased performance. Protection should be provided as early as possible in the bird’s life, before infection can occur. It should also be unaffected by the presence of any circulating maternal antibodies, allowing to overcome the ‘immunity gap’. Duration of immunity should be long. Finally, the vaccine should not have a negative impact on the bursa or immune response of the vaccinated birds.’

One vaccine that fits the bill is Vaxxitek^® HVT+IBD. This HVT-vectored IBD vaccine can be given at the hatchery in ovo or at day-old, providing early protection and avoiding the immunity gap [1].

The vaccine induces immunoprotection against all classical, variant and vvIBD strains from 14 days of age [2], and against MD from 4 days of age. Early vaccination against IBD and MD will help build the immune foundation, while improving vaccine take and performance. In doing so, control of immunodepression will greatly reduce the need for antibiotics and help decrease treatment costs.

‘Vaccination with Vaxxitek^® HVT+IBD not only protects the animals from disease and supports their immune system but it also reduces viral shedding, which decreases infection pressure and viral circulation,’ Dr Lemiere adds. ‘Thanks to its long duration of immunity, is also suitable for long-lived commercial layers and broiler breeders. Its track record in terms of improved performance have been proven for breeders [3] , broilers [4] and layers [5] .’

Vaxxitek^® IBD-HVT is compatible with a large range of MD, Fowlpox and Newcastle disease vaccines for established and customised vaccination programmes for breeders, broilers and layers.

Fig 2. Top: vaccination with a vaccine susceptible to maternal antibodies (MDA) will require late vaccination, when the MDA have waned. This leaves the birds unprotected at a crucial age. Bottom: Full protection with Vaxxitek® HVT-IBD

Immunosuppression

Immunosuppression is a state of body when the immune system or humoral (antibodies) and/or cell mediated immunity is depressed. It can have a huge economical impact as it is characterised by:

• Atrophy of lymphoid organs
• increased susceptibility to disease and secondary infections
• impaired vaccine response
• increased medication cost
• loss of flock uniformity
• increased feed conversion
• poor weight gain, reduced performance
• increased condemnation rate

Vaccinating against immunosuppression

• Vaxxitek^® HVT+IBD offers simple, safe, single vaccination for life-long protection against all known classic, variant and vv IBDV strains and Marek’s disease.
• Hatchery administration will provide an early onset active immunity not neutralised by maternal antibodies.
• Vaxxitek^® HVT+IBD will help lay the immune foundation of the birds at the hatchery, allowing a tailor-made vaccination programme according to the type of bird and the disease risk.
• By controlling immunodepression, Vaxxitek^® HVT+IBD will reduce the need for antibiotics.
• Vaxxitek^® HVT+IBD provides a broad, lifelong protection. The vaccine reduces shedding and has a duration of immunity compatible with the period of susceptibility to the IBD virus and the long-term IBD antibody production in breeders for progeny passive immunity.

References:

[1] 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.

[2] Julio S. Cruz-Coy, Clovis Oliviera, Jeaovane Pereira, Fernanda Ambrosimo, Airton Gaudenci, Francois-Xavier Le Gros and Nikki Pritchard. Efficacy of a Turkey Herpesvirus (HVT-MDV serotype 3)-Infectious Bursal Disease (IBD) Vaccine, Live HVT Vector, IBD-VP2, administered in ovo and to One-Day-Old SPF Chickens. Proceedings of the American Association of Avian Pathologists, 2006

Enrique N. Montiel, Nikki Pritchard, Amy Holderfield, Julio Cruz, Robert Smith and Kari Pack. Lymphocyte depletion, vaccine virus detection and bursal lesion in commercial broilers vaccinated with commercially available and experimental Infectious bursal disease vaccines. Proceedings of the American Association of Avian Pathologists, 2006

[3] 2013-World J Vacc-Lemiere S Al-Gumboro-vaccination-Vaxxitek HVT+IBD breeder vaccination
[4] 2013-18thWVPAC-Alonso M Al-Gumboro-vaccination-Vaxxitek HVT+IBD slaughterhouse benefits.pdf
2013-18thWVPAC-Lemiere S Al-Gumboro-vaccination-Vaxxitek HVT+IBD-alternative antibiotics.pdf
2011-XVIIthWVPAC-Herrmann A Al-Gumboro-vaccination-Vaxxitek HVT+IBD field experience Egypt.pdf
[5] 2011-XVIIthWVPAC-Horner RF-Gumboro-vaccination-Vaxxitek HVT+IBD field experience South Africa.pdf
2011-XVIIthWVPAC-Korosi L Al-Gumboro-vaccination-Vaxxitek HVT+IBD field experience Hungary.pdf
2011-XVIIthWVPAC-Ochoa R-Gumboro-vaccination-Vaxxitek HVT+IBD field experience Mexico.pdf
2013-18thWVPAC-Devaud I Al-Gumboro-vaccination-Vaxxitek HVT+IBD egg production benefits.pdf
2014-Rec Med Vet-Trotel A Al-Gumboro-vaccination-Vaxxitek HVT+IBD pullets France.pdf