Astragalus Polysaccharides Enhance the Immune Response to Newcastle Disease Virus Vaccination in Chickens

Abstract

   This study was conducted to evaluated the effects of Astragalus polysaccharide on immune responses of chickens immunized with NDV Lasota  vaccine. One hundred chickens at one-day-old( Ross breed) were brought , on five day of age, the average maternal serum Abs was measured by  hemaglutination inhibition  (HI) test and the titer  was 3.43 log, and then divided into five equal groups in each group twenty chicks and on day 10 of age the Astragalus polysaccharide high concentration  (APSH) group were given 0.5 ml at 400mg /100ml , the Astragalus polysaccharide medium concentration (APSM )group were given 0.5 ml at 200mg /100ml, the Astragalus polysaccharide low concentration  (APSL) group were given 0.5 ml at 100mg /100ml , Vaccine control (VC) group were  given 0.5 ml normal saline only, Negative control (NC ) group were  given normal saline only , all groups orally administrated for four days. At 14 day of age,  all chickens with the exception of NC group , were vaccinated with ND Lasota  by Intraocular and Intranasal methods.  Four blood sample from all groups were aspirated from jugular vein at 0h (before vaccination),6h,12h and 24h(after vaccination ) for determine of Chicken IL-6(Interleukin 6) by RT-PCR. On day 20and 30 of age after vaccination  , three chicken were sampled randomly from each group to detect specific serum  Antibody titer of  NDV by  HI test. On days 1,7,14,21after vaccination,  four serum Samples from the same of chicken to determines IgA level by sandwich  ELISA test. The cellular and humeral response including the production of cytokine IL-6 ( by RT-PCR test) were measured on 0h(before vaccination),6h,12h and 24h( after vaccination )and IgA antibody ( by ELISA test ) were measured on 1d,7d,14d,and 21days after vaccination  and serum antibody titer Specific to NDV( by HI test ) were measured at age 20, and 30 days after vaccination evaluated by series of experiments. Results revealed that all the polysaccharide groups were numerically increased in antibody levels, the expression of IL-6and IgA level ,but three parameter were significant (