The bursa of Fabricius (BF) is a central humoral immune organ unique to birds. Four bursal peptides (BP-I, BP-II, BP-III, and BP-IV) have been isolated and identified from the BF. In this study, the immunoadjuvant activities of BPs I to IV were examined in mice immunized with H9N2 avian influenza virus (AIV) vaccine. The results suggested that BP-I effectively enhanced cell-mediated immune responses, increased the secretion of Th1 (interferon gamma)- and Th2 (interleukin-4)-type cytokines, and induced an improved cytotoxic T-lymphocyte (CTL) response to the H9N2 virus. BP-II mainly elevated specific antibody production, especially neutralizing antibodies, and increased Th1- and Th2-type cytokine secretion. BP-III had no significant effect on antibody production or cell-mediated immune responses compared to those in the control group. A strong immune response at both the humoral and cellular levels was induced by BP-IV. Furthermore, a virus challenge experiment followed by H and E staining revealed that BP-I and BP-II promoted removal of the virus and conferred protection in mouse lungs. BP-IV significantly reduced viral titers and histopathological changes and contributed to protection against H9N2 AIV challenge in mouse lungs. This study further elucidated the immunoadjuvant activities of BPs I to IV, providing a novel insight into immunoadjuvants for use in vaccine design.

In order to search the availability of the lectin extracted from Korean mistletoe (Viscum album coloratum) as an adjuvant for the avian vaccines, attempts were made to determine toxicity of the lectin in chicks and its immunostimulating activity on the inactivated vaccines against Newcastle disease virus (NDV). For the determination of toxicity, the lectin was injected into the thigh muscle of SPF chicks (Charles River) of 1-week-old and observed hematologically and pathologically.

In the present study toxicity and immunostimulating activity of the lectin (KML-C), which was extracted from Korean mistletoe (Viscum album coloratum) were investigated in swine. To determine the toxicity, lectin was injected into thigh or cervical muscles of 4-week-old piglets (Landrace) and observed clinically and pathologically. For determinatio of the immunostimulating activity, lectin (0.7 ㎍/kg of body weight)-adjuvanted vaccine of Aujeszky's disease virus (ADV) (NYJ1-87) which was inactivated by 0.2% formalin was injected into the cervical muscle of antibody-negative piglets in the same age group.

Mycobacterial cell-wall skeleton (CWS) is an immunoactive and biodegradable particulate adjuvant and has been tried to use for immunotherapy. The CWS of Mycobacterium bovis bacillus Calmette-Guerin (BCG-CWS) was studied as an universal vaccine vehicle for antigen conjugation, to develop potentially effective and safe vaccine. Although a variety of biological activities of BCG-CWS have been studied, the effects of BCG-CWS on spleen cells are not fully elucidated. Using MTT assay and trypan blue exclusion test, we found that BCG-CWS significantly enhanced the viability and proliferation of cells. Multiple clusters, indicating proliferation, were observed in BCG-CWS-treated spleen cells and surface marker staining assay revealed that BCG-CWS promoted the proliferation of CD19+ B lymphocyte rather than CD4+ or CD8+ T lymphocyte. In addition, BCG-CWS up-regulated the expression of anti-apoptotic molecules such as bcl-2, bcl-xL. BCG-CWS increased the surface expression of CD25 and CD69 as well as IL-2 production of spleen cells, suggesting increased activation. Furthermore, BCG-CWS enhanced the antigen-specific cell proliferation and interferon-gamma production of spleen cells. Taken together, these results demonstrate the immunostimulatory effects of BCG-CWS on spleen cells via multiple mechanisms, providing valuable information to broaden the use of BCG-CWS in clinical and research settings.