Effect of vitamin E on the immune system of SPF birds vaccinated against infectious bronchitis virus

Abstract

In order to analyze the influence of vitamin E on the immune response of birds vaccinated and challenged with Infectious Bronchitis Virus in poultry (IBV), and which dose of vitamin E is the best to answer this, an experiment was conducted using 50 SPF birds housed with one day of life at Embrapa -Suínos e Aves. All birds were divided into 10 groups of five birds each, including positive and negative control groups, supplemented with 15, 50, and 200 IU of vitamin E/Kg added into the feed. On the 14th day of life the birds were vaccinated with a commercial vaccine for infectious bronchitis (H-120) and after 28 days, one group for each treatment was challenged with IBV, strain classical (M-41). Five days after challenge birds were necropsied and abdominal macrophages were collected for analysis of microbicidal activity and measurement of nitric oxide (NO). The lung was collected for cell count by flow cytometry and also for NO dosage. Organs of predilection were also collected for histological analysis and virus isolation to analyze the efficiency of the vaccine. The results were evaluated by ANOVA and Student t-test. An increased of microbicidal activity of abdominal macrophages was observed in the groups of birds with higher levels of vitamin E (200 IU/Kg) supplementation when compared with groups that did not receive or received minor amounts (0, 15, 50 IU/Kg), indicating an improvement in the innate immune response influenced by vitamin E supplementation in the diet. The supplementation of this vitamin in high doses also increases the ability of macrophages to produce NO. And, by flow cytometry, suggests that the macrophages are the primary cells recruited in the lung tissue to combat infectious bronchitis and this action was potentiated by the addition of vitamin E, independent of the dosage. Key words: Immunity, nutrition, vaccine, vitamin E ResumoA fim de analisar a influência da vitamina E sobre a resposta imunológica de aves vacinadas e desafiadas com o Vírus da Bronquite Infecciosa das aves (VBI), e qual dose da vitamina E é melhor para essa resposta, foi realizado um experimento utilizando 50 aves SPF alojadas com um dia de vida na Embrapa -Suínos e Aves. As aves foram divididas em 10 grupos de cinco aves cada, incluindo grupo controle positivo e negativo, suplementadas com 15, 50 e 200 UI/Kg de vitamina E na ração. No décimo quarto dia de vida as aves foram vacinadas com a vacina comercial para Bronquite Infecciosa (H-120) e após 28 dias, um grupo por tratamento foi desafiado com VBI cepa clássica (M-41). Cinco dias após o desafio as aves foram necropsiadas e os macrófagos abdominais foram coletados para análise da atividade microbicida e dosagem de óxido nítrico (NO). O pulmão foi coletado para contagem de células através de citometria de fluxo e também dosagem de NO. Órgãos de eleição também foram coletados para análise histológica e realização do isolamento viral para analisar a eficiência vacinal. Os resultados foram avaliados pelo teste ANOVA e Student t-test. Um aumento da atividade micr...