Purification and Characterization of the 64kDa Surface Protein from Mycobacterium bovis BCG

Abstract

Cancer is one of the leading causes of death now-a-days. There are various treatment options for cancer and each have their own side effects because most of the therapeutic agents of cancer are non-selective and causes cancer cell destruction as well as normal cell destruction. So, search for a highly specific therapeutic molecule is still going on. As it is known that, immune molecules are highly specific in terms of antigen-antibody reaction, immunotherapy should be a better and more specific choice for cancer therapy compared to conventional molecules in use. It was suggested by previous literatures that, a 64kDa Mycobacterium bovis BCG surface protein has antigenic similarity (as it shares common antigenic determinants) with various mouse and guinea pig cancer cells and is cross reacting to one of these cancer cell antigens (64kDa). The anti-BCG 64kDa antibody also has anticancer effects against various solid tumors of experimental animals due to same reason. But

there

was no report of similar experiment on malignant ascites cell line. Considering the above facts, we got interested in this study to assess the effects of anti-64kDa on Ehrlich’s Ascites Carcinoma (EAC) cells. In our study, we found that, mouse anti-64kDa has cytotoxic effect on HeLa cell line in vitro when compared to control and has anticancer effect on EAC cells. Pre-immunized animals (immunized with BCG 64kDa) showed 50% increase in life span compared to control and a plummeted rate of weight gain than control after challenge with EAC cells. Moreover, when Whole cell extracts of EAC cells were immunoblotted with BCG 64kDa immunized mice sera, a 64kDa band was observed. All these data suggest us that, water soluble BCG 64kDa surface antigen shares common antigenic determinants with malignant ascites cells and has anti-cancer activity in mice in terms of survival and rate of weight gain. Combining these results, we present BCG 64kDa surface antigen as a potent immunotherapeutic agent.