Comparative study of the adjuvanticity of FIA and phosphatidylcholine liposomes for purified mycobacterial RNA

In the present study, RNA isolated from Mycobacterium t ubercu losis H, Ra cells was further purified on sepharose CL-'tB which yielded three fractions i.e. F., F and F,. Out of these, F, was major fraction containing least amount of protein contamination (2.3% A comparative study of the immunoreactivity of these three fractions indicated that F. and F2 were more immunoreactive than F,. Animals immunized with F. fraction emulsified with FIA or encapsulated in egg phosphatidylcholine (EPC) liposomes induced comparable humoral and cell mediated immune (CMI) responses. Further, immunization with this fraction resulted in significant protection as revealed by high survival rate and decreased bacterial load in the infected organs as compared to nonimmunized animals on challenge with Mt uberculosi s H. Rv. Protection provided by F. using FIA and liposomes as adjuvants was quite comparable, indicating that liposomes can replace FIA for mycobacterial antigens.