Figure 6.

Binding of IgG and C3b with encapsulated strain of Bacillus anthracis incubated at different pH buffers ranging from 2.4 to 7.4, supplemented with 10% normal human serum or 50 μg/ml of purified human IgG. (A) Immunoblot assay for the detection of purified IgG binding on encapsulated strain of B. anthracis. IgG binding was observed at pH closer to the isoelectric point of poly-γ-D-glutamate (pI 3.2). (B) Purified IgG was stable at different pH buffers as detected by immunoblot. (C) Immunoblot assay for the detection of human C3b binding on encapsulated strain of B. anthracis. C3b binding was also observed at pH closer to the isoelectric point of poly-γ-D-glutamate. (D) Normal human serum (NHS) was incubated at different pH buffers and C3 was observed to be stable at low pH as analyzed by immunoblot.