Priliminary Study Of The Immunological Response On Mice Induced By Two Kinds Of Bacillus Anthracis Vaccine

Bacillus Anthracis, the etiological agent of anthrax diseases in humans and livestocks, is considered to be most likely biological warfare agents. The current vaccines foranthrax used in humans are live attenuated B.anthracis vaccine and AVA (AdsorbedAnthrax Vaccine) which has been widely used in humans since its first license. Due to thelittle understanding on the mechanism of immunological response, we investigated themechanism of the immunological response after vaccination with two kinds of Anthraxvaccines and hope to provide theoretical bases for the development and evaluation ofvaccination. Two kinds of vaccines—AVA and A16R—were employed in ourresearch.Based on the two arms of adaptive immunity—the humoral immunity and thecellular immunity, our research screened the kinetics of immunological response inducedby the Anthrax vaccines from the three respective aspects: spleen, bone marrow and blood.The study was divided into three parts. On the first part, two kinds of BacillusAnthracis vaccines were produced and evaluated on Balb/C mice. (1) Production andidentification of two kinds of vaccines; (2) Kinetics of serum antibody and its profile onBalb/C mice inoculated with AVA and A16R were analyzed. On the second part,preliminary research of B cell response on Balb/C mice induced by anthrax vaccines wasperformed. (1) First, we established the method of detecting the antigen-specific antibodysecreting cells inoculated with AVA and A16R. (2) We observe the dynamics of the B cellresponse from three different point of view—spleen, bone marrow and blood, compare thediscrepancy of the B cell response in different organs, and analyzed the response status ofdifferent organ at different time points the correlation between B cell response and serumantibody titers. The third one, we detected the Th2 cell response on Balb/C mice inducedby anthrax vaccines.Antigen-specific Th2 cell response was screened on mice afterimmunization with two kinds of Anthrax vaccine. The discrepancy of antigen-specific Th2response among different levels was compared. Results are as follows. First, high level of antigen-specific antibody was detected inserum of Balb/C mice inoculated with both vaccines. The profile of IgG antibody subtypewas dominated with IgGland IgG2b, and titers of IgG2a was much lower than theprevious ones vaccinated with AVA. Besides high level titers of IgGland IgG2b beingdetected, titers of IgG2a in A16R group were much higher than that in AVA group.Second, antigen-specific B cell response can be detected in different organ of Balb/C miceimmunized with both vaccines. Difference of the appearance time and magnitudes can beobserved in the three organs. ASC response first appeared in the spleen 14 Days postprimary immunization while little was detected in bone marrow; and antigen-specificsecreting cells peaked in spleen at 3 days post initial boost and 2nd boost respectively.Compared with that in spleen, the production of ASCs in bone marrow were detectable at14 days post primary immunization, then steadily increased, and reached to its peak at 14days post 2nd boost. The number of ASCs in bone marrow drop a little after its peak andmaintenance at a stable level, which shows a significant correlation with the level ofantibody in serum. ASCs can be detectable in blood of two groups. Third, antigen-specificTh2 response can be detected in mice immunized with two kinds of vaccines, furthermore,the kinetics of Th2 cell response is similar to that of antigen-specific secreting cellresponse in spleen and bone marrow, but a little different from that in blood. Highmagnitude of Th2 cell response was identified in blood and maintained for a long timewhich may imply its important role during the differentiation of B cells into ASCs, andASCs in bone marrow show a significant correlation with the maintenance of antibody inserum. Other parts of immune system should be considered in the evaluation of efficacy ofvaccines, and further knowledge should be updated in future for the complexity ofimmune system which was regulated by a complicated network.