Immunobiological studies with mycobacterial ribonucleic acid-protein complex: Part I--Immune responses and protective role against experimental tuberculosis.

Ribonucleic acid (RNA) isolated from M. tuberculosis H37Ra was found to be native in nature as determined by hyperchromicity studies using ribonuclease. Mycobacterial RNA-protein (Myc. RNA-P) when injected as RNA-P-FIA complexes induced weak humoral immune responses and strong cell-mediated immune (CMI) responses which were directed against Myc. RNA. Protection comparable to BCG was induced in mice immunized with RNA-FIA complexes against LD50 dose of M. tuberculosis as monitored by increased survival rates, decreased lung density, root specific lung weight (RSLW) and by decreased viable counts of M. tuberculosis in lung, liver and spleen of immunized mice. Enzymatic degradation studies revealed Myc. RNA component to specifically mediate protection while the protein component was found ineffective.