Marek Disease Vaccines (MDVs) are vaccinations specifically designed to prevent or control Marek's disease in birds, particularly chickens. Marek's disease is a highly contagious viral illness that affects domestic chickens, causing devastating economic losses in the poultry industry worldwide.
MDVs are developed from a weakened or attenuated strain of the Marek's disease virus (MDV) or its specific antigens. These vaccines are administered to healthy birds to stimulate an immune response and provide protection against the disease. There are two main types of MDVs available - live attenuated vaccines and herpesvirus of turkeys (HVT) vaccines.
Live attenuated vaccines contain weakened or non-pathogenic strains of MDV. When administered, these vaccines replicate within the bird's body, stimulating both cell-mediated and humoral immune responses. This results in the production of specific antibodies and memory cells that provide long-term protection against Marek's disease.
HVT vaccines, on the other hand, use a different virus called herpesvirus of turkeys, which is modified to express Marek's disease antigens. When administered to chickens, HVT vaccines induce an immune response that protects against Marek's disease.
MDVs are generally administered to birds at an early age, usually within the first week of life, via thimerosal-free vaccines, vaccination sprays, or in ovo vaccination techniques. These vaccines have been instrumental in controlling Marek's disease and reducing its impact on the poultry industry by preventing clinical signs, reducing tumor formation, and increasing bird survival rates.
It is important to note that MDVs do not provide complete immunity, and biosecurity measures are required to further control the spread of the virus. Additionally, different strains of MDV and the constant evolution of the virus may require periodic updates or adjustments
