This study was conducted to evaluate the effects of 4 Chinese herbal polysaccharides on the production of serum antibodies and the proliferation of peripheral T lymphocytes, including subpopulations in vaccinated chickens. A total of 450 chickens were randomly assigned to 9 groups at 14 d of age and vaccinated first with live Newcastle disease (ND)-infectious bronchitis virus vaccine, and second with ND-infectious bronchitis oil adjuvant vaccine at 28 d of age. At the same time as the first vaccination, the chickens in groups 1 to 8 were intramuscularly injected with 4 polysaccharides at high and low dosages, respectively, once a day for 3 successive days starting on the day of the first vaccination. Group 9 (control group) was injected in the same manner with saline instead of a polysaccharide. On d 7, 14, 21, 28, 35, 42, and 49 after the first vaccination, the temporal changes in serum ND hemagglutination inhibition antibody titer were determined by the micromethod. On d 10, 20, 30, 40, and 50 after the first vaccination, the proliferation of peripheral blood mononuclear cells in response to concanavalin A stimulation as well as the proportions of CD3(+), CD4(+), and CD8(+) peripheral blood mononuclear cells were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method and flow cytometry, respectively. The results showed that astragalus polysaccharide and isatis root polysaccharide at low dosages, and achyranthes root polysaccharide and Chinese yam polysaccharide at high dosages significantly enhanced the ND antibody titers, concanavalin A-induced proliferation of peripheral blood lymphocytes, and ratio of CD4(+) to CD8(+) (P <0.05). Collectively, these findings indicate that the 4 polysaccharides possess significant immune-enhancing properties in chickens. This finding may have direct application in vaccine design and other strategies designed to potentiate immune system development and function in chickens.

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We report the complete nucleotide sequence of a reassortant infectious bursal disease (IBD) virus (IBDV) HN isolate from commercial broiler flocks in central China. The genome consisted of 3,232 and 2,652 nucleotides in the coding regions of segments A and B, respectively. Alignment of both nucleotide and deduced amino acid sequences and phylogenetic analysis revealed that the genome segments A and B of HN were derived from the attenuated strain B87 and the VV strain OKYM. This is a new reassortant IBDV strain that has emerged in nature, involving segment A of a cell-culture-adapted attenuated vaccine strain B87.

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The development of strategies to augment the immunogenicity of DNA vaccines is critical for improving their clinical utility. One such strategy involves using the different immune routes with DNA vaccines. In the present study, the immunogenicity of SARS-CoV nucleocapsid DNA vaccine, induced by using the current routine vaccination routes (intramuscularly, by electroporation, or orally using live-attenuated Salmonella typhimurium), was compared in mouse model. The comparison between the three vaccination routes indicated that immunization intramuscularly induced a moderate T cell response and antibody response. Mice administrated by electroporation induced the highest antibody response among the three immunization groups and a mid-level of cellular response. In contrast, the orally DNA vaccine evoked vigorous T cell response and a weak antibody production. These results indicated that the distinct types of immune responses were generated by the different routes of DNA immunization. In addition, our results also show that the delivery of DNA vaccines by electroporation and orally using live-attenuated Salmonella in vivo is an effective method to increase the immune responses. Further studies could be carried out using a combination strategy of both oral and electroporation immunizations to stimulate higher cellular and humoral immune responses.