Immunomodulatory effect of Polyimmune (Astragalus membranaceus) extract on humoral response of layer birds vaccinated against Newcastle disease virus.

ABSTRACT Immunomodulatory effect of a commercially available phytic polysaccharide product with the name Polyimmune ( Astragalus membranaceus extract) was determined on the humoral response of Newcastle disease (ND) virus vaccine and subsequent immunosuppression caused by infectious bursal disease (IBD) vaccine in layer birds. In this study one hundred days-old layer chicks were purchased and divided into five groups namely A, B, C, D and E (20 chicks in each group) and inoculated with various combinations of vaccines with or without substitution of polyimmune. At the age of 33 days all the birds were primed with NDV vaccine and then after 12 days post priming, all the birds were given booster dose of same NDV vaccine. Similarly 7 days post boosting the birds were re-vaccinated against IBDV except group E. Whereas, groups A, B and C were substituted with varying dosage of polyimmune (for three consecutive days). Serum samples were collected at the age of 30, 45, 53, 61, 69 and 77 days of age. Haemagglutination inhibition (HI) titers of these serum samples against NDV were analyzed and the geometric mean titer of groups A, B, C, D and E as per above-mention sequence of days except for day 30, where all groups were having GMT 2.1, rest were 6.34, 7.23, 6.44, 6.10 and 7.10; 7.21, 7.34, 7.24, 7.41 and 7.31; 6.35, 7.35, 7.38, 5.46 and 7.32; 6.27, 7.41, 7.45, 3.67 and 7.21; 5.90, 7.10, 7.16, 3.40 and 6.92, respectively. The result obtained revealed that IBD have adverse effects on ND vaccine but the recommended dosage of polyimmune has immunostimulatory effect. However, varying dosage has non-significant difference in comp ensating humoral response than normal dosage.