Abstract
BackgroundThe knowledge on the immune responses to LPAI is limited. The purpose of this study was to investigate the immune responses of two divergently selected lines of broilers, a line responding with high antibody response to antigens (HH), and a line responding with low antibody titers (LL) to antigen.MethodsDay old chicks from each line were divided in two groups, one vaccinated with inactivated H9N2 vaccine and one non-vaccinated. At 21 days of age all the chicks were challenged with field isolate of H9N2, 1X106.5 ELD50 per chick by drops to the eye, nose and beak. Twenty four hours and 14 days post challenge (PC), the chickens were weighed blood spleen and lungs were taken and leukocytes were isolated. The leukocytes were stained with monoclonal antibodies for surface markers and analyzed by flow cytometry. We used Elispot assay to identify the number of antibody producing cells in each of the organs. mRNA was extracted using TRIsol reagent in order to assess the cytokine production level by qRT-PCR using the SYBR green methods.ResultsOur results showed that LL-vaccinated group gained more weight than any of the other group. Using IDEXX kit, no antibody titers could be identified in vaccinated chicks 21 days post vaccination while 14 days PC vaccinated HH chickens demonstrated the highest average antibody titers. LL vaccinated chickens demonstrated higher average antibody titer than non-vaccinated LL. Using the Elispot assay no difference were found between the groups either cells producing IgA, IgM or IgY beside of a high number of IgY producing cells in the lungs of vaccinated HH birds.ConclusionsFurther data on leukocytes subpopulations using flow cytometry, cytokines production (IFNγ, IL-6, IL-18, IL-2 and IL-4) isotype specific antibody responses and number and functionality of NK cells are in process.
Highlights
The knowledge on the immune responses to Low Pathogenic Avian Influenza (LPAI) is limited
Further data on leukocytes subpopulations using flow cytometry, cytokines production (IFNg, IL-6, IL18, IL-2 and IL-4) isotype specific antibody responses and number and functionality of NK cells are in process
avian influenza (AI) viruses are typically characterized as either being Low Pathogenic Avian Influenza (LPAI), or High pathogenic AI (HPAI) viruses
Summary
The knowledge on the immune responses to LPAI is limited. Influenza viruses of type A infect humans, horses, swine other mammals and a wide variety of domesticated and wild birds. Infection of poultry with AI viruses cause a wide range of clinical signs including mild and severe respiratory disease, producing losses and sometimes severe disease with high morbidity and mortality. AI viruses are typically characterized as either being Low Pathogenic Avian Influenza (LPAI), or High pathogenic AI (HPAI) viruses. Numerous vaccines against avian influenza (AI) have been developed and shown to be efficacious, but the number of AIV outbreaks in commercial poultry is reduced but not eradicated. With a greater understanding of the host immune response to the AI infection and vaccination, better control strategies can be developed
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