Maternally derived antibodies (MDAs) can interfere with chickens’ response to vaccinations. Antigen-specific antibodies are passed from hens to their offspring through the egg. These antibodies are called MDAs (maternal derived antibodies). MDAs may be one of the reasons why most bird flu vaccinations are not very successful in practice. This is the result of a study on which Xue Pan obtained his PhD at Wageningen University & Research.
In some countries, vaccination is the most important and widely used strategy against bird flu. However, most vaccination programs against the H9N2 virus appear to have little effect against infection and transmission in practice, despite the positive results under laboratory conditions in pathogen-free chickens (SPF chickens).
epidemiological study
Pan visited several poultry farms in China and conducted epidemiological studies in the field for more than three months. He then studied three groups of chickens in the lab. In the first group, all chickens were vaccinated one day after hatching. The second group received the vaccination at the age of 21 days, and the third group, as a control group, remained unvaccinated. All groups consisted of eight broilers and eight SPF chickens. “Our results show that maternally derived antibodies (MDAs) are likely to interfere with pre-vaccination humoral immunity in chickens,” says Pan.
More attention to MDAs
“Our results show that we need to pay more attention to the impact of MDAs on flu vaccines in the field, and not just antigenic distance,” says Pan. “It is important that new vaccines are developed that neutralize the influence of MDAs in real-life situations.” During his research, Pan developed several new vaccines, such as a new adjuvant for the conventional inactive H9N2 vaccine and a vector vaccine based on the herpes virus in turkeys that could improve the effectiveness of the vaccine in poultry. In addition, Pan investigated some other methods to improve the effectiveness of vaccination.
H9N2 bird flu
H9N2 bird flu is the most common and most dangerous low-pathogenic bird flu virus in the world. It is not only extremely dangerous for poultry farming, but also for public health. Some researchers worry that this virus could cause the next pandemic, either by jumping directly to humans or by contributing part of its genes to another pandemic influenza virus.
For more information: Xue Pan
Source: WUR