Influence of strain of chickens on the immune response to vaccination against Marek's disease

Abstract

Field trials were conducted to determine the response of different genetic strains of commercial chickens to vaccination against Marek's disease (MD).Cell-associated and cell-free HVT vaccines conferred the same degree of protection within the same strain of chickens. The incidence of MD in vaccinated birds seemed to be correlated with the natural susceptibility of the chicken strains to the disease. Revaccination did not induce better protection in the most susceptible strain.

Standardization of a model to study revaccination against Marek's disease under laboratory conditions

“…However, this practice became widespread in several countries of Europe and Asia in the late 1990s (reviewed in Gimeno, 2004). The rationale is largely anecdotal as the few published reports have failed to provide support for the value of this practice (Spencer et al, 1972;Benda & Holzanek, 1975;Zanella et al, 1975;Cho et al, 1976;Ball & Lyman, 1977;Eleazer, 1978;Riddell et al, 1978;Lee & Witter, 1991). Recently, Wu et al (2009) evaluated the positive effect of revaccination in an outbreak of MD but they were not able to reproduce experimentally the benefits of revaccination.…”

“…Other attempts have been made in the past to reproduce revaccination benefits in the laboratory (Spencer et al, 1972;Benda & Holzanek, 1975;Zanella et al, 1975;Cho et al, 1976;Ball & Lyman, 1977;Eleazer, 1978;Riddell et al, 1978;Lee & Witter, 1991;Wu et al, 2009). Most of the previous studies used homologous revaccination (Spencer et al, 1972;Benda & Holzanek, 1975;Zanella et al, 1975;Cho et al, 1976;Ball & Lyman, 1977;Eleazer, 1978;Riddell et al, 1978) and that could explain the lack of positive results. Recently, Wu et al (2009) used various combinations of vaccines, some of which were heterologous protocols.…”

“…Because of the lack of written reports, it is difficult to determine when and where the poultry industry started MD revaccination. Sporadic use of revaccination against MD under field conditions has been reported since the 1970s (Spencer et al, 1972;Benda & Holzanek, 1975;Zanella et al, 1975;Cho et al, 1976;Ball & Lyman, 1977). However, this practice became widespread in several countries of Europe and Asia in the late 1990s (reviewed in Gimeno, 2004).…”

“…The rationale behind this practice is unknown and there is no consensus on the timing or dose of the second vaccination. Despite the moderate success reported under field conditions, several attempts to demonstrate the benefit of MD revaccination under laboratory conditions have failed (Spencer et al, 1972;Benda & Holzanek, 1975;Zanella et al, 1975;Cho et al, 1976;Ball & Lyman, 1977;Eleazer, 1978;Riddell et al, 1978;Lee & Witter, 1991). A proper experimental model is crucial to better understand the seemingly sporadic successes associated with MD revaccination and to optimize it.…”